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remove RSA folder

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Jonathan Warren 2013-03-21 13:16:15 -04:00
parent 7e190c4d23
commit 3f6142ba31
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45
rsa/__init__.py
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# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""RSA module
Module for calculating large primes, and RSA encryption, decryption, signing
and verification. Includes generating public and private keys.
WARNING: this implementation does not use random padding, compression of the
cleartext input to prevent repetitions, or other common security improvements.
Use with care.
If you want to have a more secure implementation, use the functions from the
``rsa.pkcs1`` module.
"""
__author__ = "Sybren Stuvel, Barry Mead and Yesudeep Mangalapilly"
__date__ = "2012-06-17"
__version__ = '3.1.1'
from rsa.key import newkeys, PrivateKey, PublicKey
from rsa.pkcs1 import encrypt, decrypt, sign, verify, DecryptionError, \
VerificationError
# Do doctest if we're run directly
if __name__ == "__main__":
import doctest
doctest.testmod()
__all__ = ["newkeys", "encrypt", "decrypt", "sign", "verify", 'PublicKey',
'PrivateKey', 'DecryptionError', 'VerificationError']

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rsa/_compat.py
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# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Python compatibility wrappers."""
from __future__ import absolute_import
import sys
from struct import pack
try:
MAX_INT = sys.maxsize
except AttributeError:
MAX_INT = sys.maxint
MAX_INT64 = (1 << 63) - 1
MAX_INT32 = (1 << 31) - 1
MAX_INT16 = (1 << 15) - 1
# Determine the word size of the processor.
if MAX_INT == MAX_INT64:
# 64-bit processor.
MACHINE_WORD_SIZE = 64
elif MAX_INT == MAX_INT32:
# 32-bit processor.
MACHINE_WORD_SIZE = 32
else:
# Else we just assume 64-bit processor keeping up with modern times.
MACHINE_WORD_SIZE = 64
try:
# < Python3
unicode_type = unicode
have_python3 = False
except NameError:
# Python3.
unicode_type = str
have_python3 = True
# Fake byte literals.
if str is unicode_type:
def byte_literal(s):
return s.encode('latin1')
else:
def byte_literal(s):
return s
# ``long`` is no more. Do type detection using this instead.
try:
integer_types = (int, long)
except NameError:
integer_types = (int,)
b = byte_literal
try:
# Python 2.6 or higher.
bytes_type = bytes
except NameError:
# Python 2.5
bytes_type = str
# To avoid calling b() multiple times in tight loops.
ZERO_BYTE = b('\x00')
EMPTY_BYTE = b('')
def is_bytes(obj):
"""
Determines whether the given value is a byte string.
:param obj:
The value to test.
:returns:
``True`` if ``value`` is a byte string; ``False`` otherwise.
"""
return isinstance(obj, bytes_type)
def is_integer(obj):
"""
Determines whether the given value is an integer.
:param obj:
The value to test.
:returns:
``True`` if ``value`` is an integer; ``False`` otherwise.
"""
return isinstance(obj, integer_types)
def byte(num):
"""
Converts a number between 0 and 255 (both inclusive) to a base-256 (byte)
representation.
Use it as a replacement for ``chr`` where you are expecting a byte
because this will work on all current versions of Python::
:param num:
An unsigned integer between 0 and 255 (both inclusive).
:returns:
A single byte.
"""
return pack("B", num)
def get_word_alignment(num, force_arch=64,
_machine_word_size=MACHINE_WORD_SIZE):
"""
Returns alignment details for the given number based on the platform
Python is running on.
:param num:
Unsigned integral number.
:param force_arch:
If you don't want to use 64-bit unsigned chunks, set this to
anything other than 64. 32-bit chunks will be preferred then.
Default 64 will be used when on a 64-bit machine.
:param _machine_word_size:
(Internal) The machine word size used for alignment.
:returns:
4-tuple::
(word_bits, word_bytes,
max_uint, packing_format_type)
"""
max_uint64 = 0xffffffffffffffff
max_uint32 = 0xffffffff
max_uint16 = 0xffff
max_uint8 = 0xff
if force_arch == 64 and _machine_word_size >= 64 and num > max_uint32:
# 64-bit unsigned integer.
return 64, 8, max_uint64, "Q"
elif num > max_uint16:
# 32-bit unsigned integer
return 32, 4, max_uint32, "L"
elif num > max_uint8:
# 16-bit unsigned integer.
return 16, 2, max_uint16, "H"
else:
# 8-bit unsigned integer.
return 8, 1, max_uint8, "B"

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rsa/_version133.py
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"""RSA module
pri = k[1] //Private part of keys d,p,q
Module for calculating large primes, and RSA encryption, decryption,
signing and verification. Includes generating public and private keys.
WARNING: this code implements the mathematics of RSA. It is not suitable for
real-world secure cryptography purposes. It has not been reviewed by a security
expert. It does not include padding of data. There are many ways in which the
output of this module, when used without any modification, can be sucessfully
attacked.
"""
__author__ = "Sybren Stuvel, Marloes de Boer and Ivo Tamboer"
__date__ = "2010-02-05"
__version__ = '1.3.3'
# NOTE: Python's modulo can return negative numbers. We compensate for
# this behaviour using the abs() function
from cPickle import dumps, loads
import base64
import math
import os
import random
import sys
import types
import zlib
from rsa._compat import byte
# Display a warning that this insecure version is imported.
import warnings
warnings.warn('Insecure version of the RSA module is imported as %s, be careful'
% __name__)
def gcd(p, q):
"""Returns the greatest common divisor of p and q
>>> gcd(42, 6)
6
"""
if p<q: return gcd(q, p)
if q == 0: return p
return gcd(q, abs(p%q))
def bytes2int(bytes):
"""Converts a list of bytes or a string to an integer
>>> (128*256 + 64)*256 + + 15
8405007
>>> l = [128, 64, 15]
>>> bytes2int(l)
8405007
"""
if not (type(bytes) is types.ListType or type(bytes) is types.StringType):
raise TypeError("You must pass a string or a list")
# Convert byte stream to integer
integer = 0
for byte in bytes:
integer *= 256
if type(byte) is types.StringType: byte = ord(byte)
integer += byte
return integer
def int2bytes(number):
"""Converts a number to a string of bytes
>>> bytes2int(int2bytes(123456789))
123456789
"""
if not (type(number) is types.LongType or type(number) is types.IntType):
raise TypeError("You must pass a long or an int")
string = ""
while number > 0:
string = "%s%s" % (byte(number & 0xFF), string)
number /= 256
return string
def fast_exponentiation(a, p, n):
"""Calculates r = a^p mod n
"""
result = a % n
remainders = []
while p != 1:
remainders.append(p & 1)
p = p >> 1
while remainders:
rem = remainders.pop()
result = ((a ** rem) * result ** 2) % n
return result
def read_random_int(nbits):
"""Reads a random integer of approximately nbits bits rounded up
to whole bytes"""
nbytes = ceil(nbits/8.)
randomdata = os.urandom(nbytes)
return bytes2int(randomdata)
def ceil(x):
"""ceil(x) -> int(math.ceil(x))"""
return int(math.ceil(x))
def randint(minvalue, maxvalue):
"""Returns a random integer x with minvalue <= x <= maxvalue"""
# Safety - get a lot of random data even if the range is fairly
# small
min_nbits = 32
# The range of the random numbers we need to generate
range = maxvalue - minvalue
# Which is this number of bytes
rangebytes = ceil(math.log(range, 2) / 8.)
# Convert to bits, but make sure it's always at least min_nbits*2
rangebits = max(rangebytes * 8, min_nbits * 2)
# Take a random number of bits between min_nbits and rangebits
nbits = random.randint(min_nbits, rangebits)
return (read_random_int(nbits) % range) + minvalue
def fermat_little_theorem(p):
"""Returns 1 if p may be prime, and something else if p definitely
is not prime"""
a = randint(1, p-1)
return fast_exponentiation(a, p-1, p)
def jacobi(a, b):
"""Calculates the value of the Jacobi symbol (a/b)
"""
if a % b == 0:
return 0
result = 1
while a > 1:
if a & 1:
if ((a-1)*(b-1) >> 2) & 1:
result = -result
b, a = a, b % a
else:
if ((b ** 2 - 1) >> 3) & 1:
result = -result
a = a >> 1
return result
def jacobi_witness(x, n):
"""Returns False if n is an Euler pseudo-prime with base x, and
True otherwise.
"""
j = jacobi(x, n) % n
f = fast_exponentiation(x, (n-1)/2, n)
if j == f: return False
return True
def randomized_primality_testing(n, k):
"""Calculates whether n is composite (which is always correct) or
prime (which is incorrect with error probability 2**-k)
Returns False if the number if composite, and True if it's
probably prime.
"""
q = 0.5 # Property of the jacobi_witness function
# t = int(math.ceil(k / math.log(1/q, 2)))
t = ceil(k / math.log(1/q, 2))
for i in range(t+1):
x = randint(1, n-1)
if jacobi_witness(x, n): return False
return True
def is_prime(number):
"""Returns True if the number is prime, and False otherwise.
>>> is_prime(42)
0
>>> is_prime(41)
1
"""
"""
if not fermat_little_theorem(number) == 1:
# Not prime, according to Fermat's little theorem
return False
"""
if randomized_primality_testing(number, 5):
# Prime, according to Jacobi
return True
# Not prime
return False
def getprime(nbits):
"""Returns a prime number of max. 'math.ceil(nbits/8)*8' bits. In
other words: nbits is rounded up to whole bytes.
>>> p = getprime(8)
>>> is_prime(p-1)
0
>>> is_prime(p)
1
>>> is_prime(p+1)
0
"""
nbytes = int(math.ceil(nbits/8.))
while True:
integer = read_random_int(nbits)
# Make sure it's odd
integer |= 1
# Test for primeness
if is_prime(integer): break
# Retry if not prime
return integer
def are_relatively_prime(a, b):
"""Returns True if a and b are relatively prime, and False if they
are not.
>>> are_relatively_prime(2, 3)
1
>>> are_relatively_prime(2, 4)
0
"""
d = gcd(a, b)
return (d == 1)
def find_p_q(nbits):
"""Returns a tuple of two different primes of nbits bits"""
p = getprime(nbits)
while True:
q = getprime(nbits)
if not q == p: break
return (p, q)
def extended_euclid_gcd(a, b):
"""Returns a tuple (d, i, j) such that d = gcd(a, b) = ia + jb
"""
if b == 0:
return (a, 1, 0)
q = abs(a % b)
r = long(a / b)
(d, k, l) = extended_euclid_gcd(b, q)
return (d, l, k - l*r)
# Main function: calculate encryption and decryption keys
def calculate_keys(p, q, nbits):
"""Calculates an encryption and a decryption key for p and q, and
returns them as a tuple (e, d)"""
n = p * q
phi_n = (p-1) * (q-1)
while True:
# Make sure e has enough bits so we ensure "wrapping" through
# modulo n
e = getprime(max(8, nbits/2))
if are_relatively_prime(e, n) and are_relatively_prime(e, phi_n): break
(d, i, j) = extended_euclid_gcd(e, phi_n)
if not d == 1:
raise Exception("e (%d) and phi_n (%d) are not relatively prime" % (e, phi_n))
if not (e * i) % phi_n == 1:
raise Exception("e (%d) and i (%d) are not mult. inv. modulo phi_n (%d)" % (e, i, phi_n))
return (e, i)
def gen_keys(nbits):
"""Generate RSA keys of nbits bits. Returns (p, q, e, d).
Note: this can take a long time, depending on the key size.
"""
while True:
(p, q) = find_p_q(nbits)
(e, d) = calculate_keys(p, q, nbits)
# For some reason, d is sometimes negative. We don't know how
# to fix it (yet), so we keep trying until everything is shiny
if d > 0: break
return (p, q, e, d)
def gen_pubpriv_keys(nbits):
"""Generates public and private keys, and returns them as (pub,
priv).
The public key consists of a dict {e: ..., , n: ....). The private
key consists of a dict {d: ...., p: ...., q: ....).
"""
(p, q, e, d) = gen_keys(nbits)
return ( {'e': e, 'n': p*q}, {'d': d, 'p': p, 'q': q} )
def encrypt_int(message, ekey, n):
"""Encrypts a message using encryption key 'ekey', working modulo
n"""
if type(message) is types.IntType:
return encrypt_int(long(message), ekey, n)
if not type(message) is types.LongType:
raise TypeError("You must pass a long or an int")
if message > 0 and \
math.floor(math.log(message, 2)) > math.floor(math.log(n, 2)):
raise OverflowError("The message is too long")
return fast_exponentiation(message, ekey, n)
def decrypt_int(cyphertext, dkey, n):
"""Decrypts a cypher text using the decryption key 'dkey', working
modulo n"""
return encrypt_int(cyphertext, dkey, n)
def sign_int(message, dkey, n):
"""Signs 'message' using key 'dkey', working modulo n"""
return decrypt_int(message, dkey, n)
def verify_int(signed, ekey, n):
"""verifies 'signed' using key 'ekey', working modulo n"""
return encrypt_int(signed, ekey, n)
def picklechops(chops):
"""Pickles and base64encodes it's argument chops"""
value = zlib.compress(dumps(chops))
encoded = base64.encodestring(value)
return encoded.strip()
def unpicklechops(string):
"""base64decodes and unpickes it's argument string into chops"""
return loads(zlib.decompress(base64.decodestring(string)))
def chopstring(message, key, n, funcref):
"""Splits 'message' into chops that are at most as long as n,
converts these into integers, and calls funcref(integer, key, n)
for each chop.
Used by 'encrypt' and 'sign'.
"""
msglen = len(message)
mbits = msglen * 8
nbits = int(math.floor(math.log(n, 2)))
nbytes = nbits / 8
blocks = msglen / nbytes
if msglen % nbytes > 0:
blocks += 1
cypher = []
for bindex in range(blocks):
offset = bindex * nbytes
block = message[offset:offset+nbytes]
value = bytes2int(block)
cypher.append(funcref(value, key, n))
return picklechops(cypher)
def gluechops(chops, key, n, funcref):
"""Glues chops back together into a string. calls
funcref(integer, key, n) for each chop.
Used by 'decrypt' and 'verify'.
"""
message = ""
chops = unpicklechops(chops)
for cpart in chops:
mpart = funcref(cpart, key, n)
message += int2bytes(mpart)
return message
def encrypt(message, key):
"""Encrypts a string 'message' with the public key 'key'"""
return chopstring(message, key['e'], key['n'], encrypt_int)
def sign(message, key):
"""Signs a string 'message' with the private key 'key'"""
return chopstring(message, key['d'], key['p']*key['q'], decrypt_int)
def decrypt(cypher, key):
"""Decrypts a cypher with the private key 'key'"""
return gluechops(cypher, key['d'], key['p']*key['q'], decrypt_int)
def verify(cypher, key):
"""Verifies a cypher with the public key 'key'"""
return gluechops(cypher, key['e'], key['n'], encrypt_int)
# Do doctest if we're not imported
if __name__ == "__main__":
import doctest
doctest.testmod()
__all__ = ["gen_pubpriv_keys", "encrypt", "decrypt", "sign", "verify"]

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rsa/_version200.py
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"""RSA module
Module for calculating large primes, and RSA encryption, decryption,
signing and verification. Includes generating public and private keys.
WARNING: this implementation does not use random padding, compression of the
cleartext input to prevent repetitions, or other common security improvements.
Use with care.
"""
__author__ = "Sybren Stuvel, Marloes de Boer, Ivo Tamboer, and Barry Mead"
__date__ = "2010-02-08"
__version__ = '2.0'
import math
import os
import random
import sys
import types
from rsa._compat import byte
# Display a warning that this insecure version is imported.
import warnings
warnings.warn('Insecure version of the RSA module is imported as %s' % __name__)
def bit_size(number):
"""Returns the number of bits required to hold a specific long number"""
return int(math.ceil(math.log(number,2)))
def gcd(p, q):
"""Returns the greatest common divisor of p and q
>>> gcd(48, 180)
12
"""
# Iterateive Version is faster and uses much less stack space
while q != 0:
if p < q: (p,q) = (q,p)
(p,q) = (q, p % q)
return p
def bytes2int(bytes):
"""Converts a list of bytes or a string to an integer
>>> (((128 * 256) + 64) * 256) + 15
8405007
>>> l = [128, 64, 15]
>>> bytes2int(l) #same as bytes2int('\x80@\x0f')
8405007
"""
if not (type(bytes) is types.ListType or type(bytes) is types.StringType):
raise TypeError("You must pass a string or a list")
# Convert byte stream to integer
integer = 0
for byte in bytes:
integer *= 256
if type(byte) is types.StringType: byte = ord(byte)
integer += byte
return integer
def int2bytes(number):
"""
Converts a number to a string of bytes
"""
if not (type(number) is types.LongType or type(number) is types.IntType):
raise TypeError("You must pass a long or an int")
string = ""
while number > 0:
string = "%s%s" % (byte(number & 0xFF), string)
number /= 256
return string
def to64(number):
"""Converts a number in the range of 0 to 63 into base 64 digit
character in the range of '0'-'9', 'A'-'Z', 'a'-'z','-','_'.
>>> to64(10)
'A'
"""
if not (type(number) is types.LongType or type(number) is types.IntType):
raise TypeError("You must pass a long or an int")
if 0 <= number <= 9: #00-09 translates to '0' - '9'
return byte(number + 48)
if 10 <= number <= 35:
return byte(number + 55) #10-35 translates to 'A' - 'Z'
if 36 <= number <= 61:
return byte(number + 61) #36-61 translates to 'a' - 'z'
if number == 62: # 62 translates to '-' (minus)
return byte(45)
if number == 63: # 63 translates to '_' (underscore)
return byte(95)
raise ValueError('Invalid Base64 value: %i' % number)
def from64(number):
"""Converts an ordinal character value in the range of
0-9,A-Z,a-z,-,_ to a number in the range of 0-63.
>>> from64(49)
1
"""
if not (type(number) is types.LongType or type(number) is types.IntType):
raise TypeError("You must pass a long or an int")
if 48 <= number <= 57: #ord('0') - ord('9') translates to 0-9
return(number - 48)
if 65 <= number <= 90: #ord('A') - ord('Z') translates to 10-35
return(number - 55)
if 97 <= number <= 122: #ord('a') - ord('z') translates to 36-61
return(number - 61)
if number == 45: #ord('-') translates to 62
return(62)
if number == 95: #ord('_') translates to 63
return(63)
raise ValueError('Invalid Base64 value: %i' % number)
def int2str64(number):
"""Converts a number to a string of base64 encoded characters in
the range of '0'-'9','A'-'Z,'a'-'z','-','_'.
>>> int2str64(123456789)
'7MyqL'
"""
if not (type(number) is types.LongType or type(number) is types.IntType):
raise TypeError("You must pass a long or an int")
string = ""
while number > 0:
string = "%s%s" % (to64(number & 0x3F), string)
number /= 64
return string
def str642int(string):
"""Converts a base64 encoded string into an integer.
The chars of this string in in the range '0'-'9','A'-'Z','a'-'z','-','_'
>>> str642int('7MyqL')
123456789
"""
if not (type(string) is types.ListType or type(string) is types.StringType):
raise TypeError("You must pass a string or a list")
integer = 0
for byte in string:
integer *= 64
if type(byte) is types.StringType: byte = ord(byte)
integer += from64(byte)
return integer
def read_random_int(nbits):
"""Reads a random integer of approximately nbits bits rounded up
to whole bytes"""
nbytes = int(math.ceil(nbits/8.))
randomdata = os.urandom(nbytes)
return bytes2int(randomdata)
def randint(minvalue, maxvalue):
"""Returns a random integer x with minvalue <= x <= maxvalue"""
# Safety - get a lot of random data even if the range is fairly
# small
min_nbits = 32
# The range of the random numbers we need to generate
range = (maxvalue - minvalue) + 1
# Which is this number of bytes
rangebytes = ((bit_size(range) + 7) / 8)
# Convert to bits, but make sure it's always at least min_nbits*2
rangebits = max(rangebytes * 8, min_nbits * 2)
# Take a random number of bits between min_nbits and rangebits
nbits = random.randint(min_nbits, rangebits)
return (read_random_int(nbits) % range) + minvalue
def jacobi(a, b):
"""Calculates the value of the Jacobi symbol (a/b)
where both a and b are positive integers, and b is odd
"""
if a == 0: return 0
result = 1
while a > 1:
if a & 1:
if ((a-1)*(b-1) >> 2) & 1:
result = -result
a, b = b % a, a
else:
if (((b * b) - 1) >> 3) & 1:
result = -result
a >>= 1
if a == 0: return 0
return result
def jacobi_witness(x, n):
"""Returns False if n is an Euler pseudo-prime with base x, and
True otherwise.
"""
j = jacobi(x, n) % n
f = pow(x, (n-1)/2, n)
if j == f: return False
return True
def randomized_primality_testing(n, k):
"""Calculates whether n is composite (which is always correct) or
prime (which is incorrect with error probability 2**-k)
Returns False if the number is composite, and True if it's
probably prime.
"""
# 50% of Jacobi-witnesses can report compositness of non-prime numbers
for i in range(k):
x = randint(1, n-1)
if jacobi_witness(x, n): return False
return True
def is_prime(number):
"""Returns True if the number is prime, and False otherwise.
>>> is_prime(42)
0
>>> is_prime(41)
1
"""
if randomized_primality_testing(number, 6):
# Prime, according to Jacobi
return True
# Not prime
return False
def getprime(nbits):
"""Returns a prime number of max. 'math.ceil(nbits/8)*8' bits. In
other words: nbits is rounded up to whole bytes.
>>> p = getprime(8)
>>> is_prime(p-1)
0
>>> is_prime(p)
1
>>> is_prime(p+1)
0
"""
while True:
integer = read_random_int(nbits)
# Make sure it's odd
integer |= 1
# Test for primeness
if is_prime(integer): break
# Retry if not prime
return integer
def are_relatively_prime(a, b):
"""Returns True if a and b are relatively prime, and False if they
are not.
>>> are_relatively_prime(2, 3)
1
>>> are_relatively_prime(2, 4)
0
"""
d = gcd(a, b)
return (d == 1)
def find_p_q(nbits):
"""Returns a tuple of two different primes of nbits bits"""
pbits = nbits + (nbits/16) #Make sure that p and q aren't too close
qbits = nbits - (nbits/16) #or the factoring programs can factor n
p = getprime(pbits)
while True:
q = getprime(qbits)
#Make sure p and q are different.
if not q == p: break
return (p, q)
def extended_gcd(a, b):
"""Returns a tuple (r, i, j) such that r = gcd(a, b) = ia + jb
"""
# r = gcd(a,b) i = multiplicitive inverse of a mod b
# or j = multiplicitive inverse of b mod a
# Neg return values for i or j are made positive mod b or a respectively
# Iterateive Version is faster and uses much less stack space
x = 0
y = 1
lx = 1
ly = 0
oa = a #Remember original a/b to remove
ob = b #negative values from return results
while b != 0:
q = long(a/b)
(a, b) = (b, a % b)
(x, lx) = ((lx - (q * x)),x)
(y, ly) = ((ly - (q * y)),y)
if (lx < 0): lx += ob #If neg wrap modulo orignal b
if (ly < 0): ly += oa #If neg wrap modulo orignal a
return (a, lx, ly) #Return only positive values
# Main function: calculate encryption and decryption keys
def calculate_keys(p, q, nbits):
"""Calculates an encryption and a decryption key for p and q, and
returns them as a tuple (e, d)"""
n = p * q
phi_n = (p-1) * (q-1)
while True:
# Make sure e has enough bits so we ensure "wrapping" through
# modulo n
e = max(65537,getprime(nbits/4))
if are_relatively_prime(e, n) and are_relatively_prime(e, phi_n): break
(d, i, j) = extended_gcd(e, phi_n)
if not d == 1:
raise Exception("e (%d) and phi_n (%d) are not relatively prime" % (e, phi_n))
if (i < 0):
raise Exception("New extended_gcd shouldn't return negative values")
if not (e * i) % phi_n == 1:
raise Exception("e (%d) and i (%d) are not mult. inv. modulo phi_n (%d)" % (e, i, phi_n))
return (e, i)
def gen_keys(nbits):
"""Generate RSA keys of nbits bits. Returns (p, q, e, d).
Note: this can take a long time, depending on the key size.
"""
(p, q) = find_p_q(nbits)
(e, d) = calculate_keys(p, q, nbits)
return (p, q, e, d)
def newkeys(nbits):
"""Generates public and private keys, and returns them as (pub,
priv).
The public key consists of a dict {e: ..., , n: ....). The private
key consists of a dict {d: ...., p: ...., q: ....).
"""
nbits = max(9,nbits) # Don't let nbits go below 9 bits
(p, q, e, d) = gen_keys(nbits)
return ( {'e': e, 'n': p*q}, {'d': d, 'p': p, 'q': q} )
def encrypt_int(message, ekey, n):
"""Encrypts a message using encryption key 'ekey', working modulo n"""
if type(message) is types.IntType:
message = long(message)
if not type(message) is types.LongType:
raise TypeError("You must pass a long or int")
if message < 0 or message > n:
raise OverflowError("The message is too long")
#Note: Bit exponents start at zero (bit counts start at 1) this is correct
safebit = bit_size(n) - 2 #compute safe bit (MSB - 1)
message += (1 << safebit) #add safebit to ensure folding
return pow(message, ekey, n)
def decrypt_int(cyphertext, dkey, n):
"""Decrypts a cypher text using the decryption key 'dkey', working
modulo n"""
message = pow(cyphertext, dkey, n)
safebit = bit_size(n) - 2 #compute safe bit (MSB - 1)
message -= (1 << safebit) #remove safebit before decode
return message
def encode64chops(chops):
"""base64encodes chops and combines them into a ',' delimited string"""
chips = [] #chips are character chops
for value in chops:
chips.append(int2str64(value))
#delimit chops with comma
encoded = ','.join(chips)
return encoded
def decode64chops(string):
"""base64decodes and makes a ',' delimited string into chops"""
chips = string.split(',') #split chops at commas
chops = []
for string in chips: #make char chops (chips) into chops
chops.append(str642int(string))
return chops
def chopstring(message, key, n, funcref):
"""Chops the 'message' into integers that fit into n,
leaving room for a safebit to be added to ensure that all
messages fold during exponentiation. The MSB of the number n
is not independant modulo n (setting it could cause overflow), so
use the next lower bit for the safebit. Therefore reserve 2-bits
in the number n for non-data bits. Calls specified encryption
function for each chop.
Used by 'encrypt' and 'sign'.
"""
msglen = len(message)
mbits = msglen * 8
#Set aside 2-bits so setting of safebit won't overflow modulo n.
nbits = bit_size(n) - 2 # leave room for safebit
nbytes = nbits / 8
blocks = msglen / nbytes
if msglen % nbytes > 0:
blocks += 1
cypher = []
for bindex in range(blocks):
offset = bindex * nbytes
block = message[offset:offset+nbytes]
value = bytes2int(block)
cypher.append(funcref(value, key, n))
return encode64chops(cypher) #Encode encrypted ints to base64 strings
def gluechops(string, key, n, funcref):
"""Glues chops back together into a string. calls
funcref(integer, key, n) for each chop.
Used by 'decrypt' and 'verify'.
"""
message = ""
chops = decode64chops(string) #Decode base64 strings into integer chops
for cpart in chops:
mpart = funcref(cpart, key, n) #Decrypt each chop
message += int2bytes(mpart) #Combine decrypted strings into a msg
return message
def encrypt(message, key):
"""Encrypts a string 'message' with the public key 'key'"""
if 'n' not in key:
raise Exception("You must use the public key with encrypt")
return chopstring(message, key['e'], key['n'], encrypt_int)
def sign(message, key):
"""Signs a string 'message' with the private key 'key'"""
if 'p' not in key:
raise Exception("You must use the private key with sign")
return chopstring(message, key['d'], key['p']*key['q'], encrypt_int)
def decrypt(cypher, key):
"""Decrypts a string 'cypher' with the private key 'key'"""
if 'p' not in key:
raise Exception("You must use the private key with decrypt")
return gluechops(cypher, key['d'], key['p']*key['q'], decrypt_int)
def verify(cypher, key):
"""Verifies a string 'cypher' with the public key 'key'"""
if 'n' not in key:
raise Exception("You must use the public key with verify")
return gluechops(cypher, key['e'], key['n'], decrypt_int)
# Do doctest if we're not imported
if __name__ == "__main__":
import doctest
doctest.testmod()
__all__ = ["newkeys", "encrypt", "decrypt", "sign", "verify"]

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rsa/bigfile.py
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# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Large file support
- break a file into smaller blocks, and encrypt them, and store the
encrypted blocks in another file.
- take such an encrypted files, decrypt its blocks, and reconstruct the
original file.
The encrypted file format is as follows, where || denotes byte concatenation:
FILE := VERSION || BLOCK || BLOCK ...
BLOCK := LENGTH || DATA
LENGTH := varint-encoded length of the subsequent data. Varint comes from
Google Protobuf, and encodes an integer into a variable number of bytes.
Each byte uses the 7 lowest bits to encode the value. The highest bit set
to 1 indicates the next byte is also part of the varint. The last byte will
have this bit set to 0.
This file format is called the VARBLOCK format, in line with the varint format
used to denote the block sizes.
'''
from rsa import key, common, pkcs1, varblock
from rsa._compat import byte
def encrypt_bigfile(infile, outfile, pub_key):
'''Encrypts a file, writing it to 'outfile' in VARBLOCK format.
:param infile: file-like object to read the cleartext from
:param outfile: file-like object to write the crypto in VARBLOCK format to
:param pub_key: :py:class:`rsa.PublicKey` to encrypt with
'''
if not isinstance(pub_key, key.PublicKey):
raise TypeError('Public key required, but got %r' % pub_key)
key_bytes = common.bit_size(pub_key.n) // 8
blocksize = key_bytes - 11 # keep space for PKCS#1 padding
# Write the version number to the VARBLOCK file
outfile.write(byte(varblock.VARBLOCK_VERSION))
# Encrypt and write each block
for block in varblock.yield_fixedblocks(infile, blocksize):
crypto = pkcs1.encrypt(block, pub_key)
varblock.write_varint(outfile, len(crypto))
outfile.write(crypto)
def decrypt_bigfile(infile, outfile, priv_key):
'''Decrypts an encrypted VARBLOCK file, writing it to 'outfile'
:param infile: file-like object to read the crypto in VARBLOCK format from
:param outfile: file-like object to write the cleartext to
:param priv_key: :py:class:`rsa.PrivateKey` to decrypt with
'''
if not isinstance(priv_key, key.PrivateKey):
raise TypeError('Private key required, but got %r' % priv_key)
for block in varblock.yield_varblocks(infile):
cleartext = pkcs1.decrypt(block, priv_key)
outfile.write(cleartext)
__all__ = ['encrypt_bigfile', 'decrypt_bigfile']

379
rsa/cli.py
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# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Commandline scripts.
These scripts are called by the executables defined in setup.py.
'''
from __future__ import with_statement, print_function
import abc
import sys
from optparse import OptionParser
import rsa
import rsa.bigfile
import rsa.pkcs1
HASH_METHODS = sorted(rsa.pkcs1.HASH_METHODS.keys())
def keygen():
'''Key generator.'''
# Parse the CLI options
parser = OptionParser(usage='usage: %prog [options] keysize',
description='Generates a new RSA keypair of "keysize" bits.')
parser.add_option('--pubout', type='string',
help='Output filename for the public key. The public key is '
'not saved if this option is not present. You can use '
'pyrsa-priv2pub to create the public key file later.')
parser.add_option('-o', '--out', type='string',
help='Output filename for the private key. The key is '
'written to stdout if this option is not present.')
parser.add_option('--form',
help='key format of the private and public keys - default PEM',
choices=('PEM', 'DER'), default='PEM')
(cli, cli_args) = parser.parse_args(sys.argv[1:])
if len(cli_args) != 1:
parser.print_help()
raise SystemExit(1)
try:
keysize = int(cli_args[0])
except ValueError:
parser.print_help()
print('Not a valid number: %s' % cli_args[0], file=sys.stderr)
raise SystemExit(1)
print('Generating %i-bit key' % keysize, file=sys.stderr)
(pub_key, priv_key) = rsa.newkeys(keysize)
# Save public key
if cli.pubout:
print('Writing public key to %s' % cli.pubout, file=sys.stderr)
data = pub_key.save_pkcs1(format=cli.form)
with open(cli.pubout, 'wb') as outfile:
outfile.write(data)
# Save private key
data = priv_key.save_pkcs1(format=cli.form)
if cli.out:
print('Writing private key to %s' % cli.out, file=sys.stderr)
with open(cli.out, 'wb') as outfile:
outfile.write(data)
else:
print('Writing private key to stdout', file=sys.stderr)
sys.stdout.write(data)
class CryptoOperation(object):
'''CLI callable that operates with input, output, and a key.'''
__metaclass__ = abc.ABCMeta
keyname = 'public' # or 'private'
usage = 'usage: %%prog [options] %(keyname)s_key'
description = None
operation = 'decrypt'
operation_past = 'decrypted'
operation_progressive = 'decrypting'
input_help = 'Name of the file to %(operation)s. Reads from stdin if ' \
'not specified.'
output_help = 'Name of the file to write the %(operation_past)s file ' \
'to. Written to stdout if this option is not present.'
expected_cli_args = 1
has_output = True
key_class = rsa.PublicKey
def __init__(self):
self.usage = self.usage % self.__class__.__dict__
self.input_help = self.input_help % self.__class__.__dict__
self.output_help = self.output_help % self.__class__.__dict__
@abc.abstractmethod
def perform_operation(self, indata, key, cli_args=None):
'''Performs the program's operation.
Implement in a subclass.
:returns: the data to write to the output.
'''
def __call__(self):
'''Runs the program.'''
(cli, cli_args) = self.parse_cli()
key = self.read_key(cli_args[0], cli.keyform)
indata = self.read_infile(cli.input)
print(self.operation_progressive.title(), file=sys.stderr)
outdata = self.perform_operation(indata, key, cli_args)
if self.has_output:
self.write_outfile(outdata, cli.output)
def parse_cli(self):
'''Parse the CLI options
:returns: (cli_opts, cli_args)
'''
parser = OptionParser(usage=self.usage, description=self.description)
parser.add_option('-i', '--input', type='string', help=self.input_help)
if self.has_output:
parser.add_option('-o', '--output', type='string', help=self.output_help)
parser.add_option('--keyform',
help='Key format of the %s key - default PEM' % self.keyname,
choices=('PEM', 'DER'), default='PEM')
(cli, cli_args) = parser.parse_args(sys.argv[1:])
if len(cli_args) != self.expected_cli_args:
parser.print_help()
raise SystemExit(1)
return (cli, cli_args)
def read_key(self, filename, keyform):
'''Reads a public or private key.'''
print('Reading %s key from %s' % (self.keyname, filename), file=sys.stderr)
with open(filename, 'rb') as keyfile:
keydata = keyfile.read()
return self.key_class.load_pkcs1(keydata, keyform)
def read_infile(self, inname):
'''Read the input file'''
if inname:
print('Reading input from %s' % inname, file=sys.stderr)
with open(inname, 'rb') as infile:
return infile.read()
print('Reading input from stdin', file=sys.stderr)
return sys.stdin.read()
def write_outfile(self, outdata, outname):
'''Write the output file'''
if outname:
print('Writing output to %s' % outname, file=sys.stderr)
with open(outname, 'wb') as outfile:
outfile.write(outdata)
else:
print('Writing output to stdout', file=sys.stderr)
sys.stdout.write(outdata)
class EncryptOperation(CryptoOperation):
'''Encrypts a file.'''
keyname = 'public'
description = ('Encrypts a file. The file must be shorter than the key '
'length in order to be encrypted. For larger files, use the '
'pyrsa-encrypt-bigfile command.')
operation = 'encrypt'
operation_past = 'encrypted'
operation_progressive = 'encrypting'
def perform_operation(self, indata, pub_key, cli_args=None):
'''Encrypts files.'''
return rsa.encrypt(indata, pub_key)
class DecryptOperation(CryptoOperation):
'''Decrypts a file.'''
keyname = 'private'
description = ('Decrypts a file. The original file must be shorter than '
'the key length in order to have been encrypted. For larger '
'files, use the pyrsa-decrypt-bigfile command.')
operation = 'decrypt'
operation_past = 'decrypted'
operation_progressive = 'decrypting'
key_class = rsa.PrivateKey
def perform_operation(self, indata, priv_key, cli_args=None):
'''Decrypts files.'''
return rsa.decrypt(indata, priv_key)
class SignOperation(CryptoOperation):
'''Signs a file.'''
keyname = 'private'
usage = 'usage: %%prog [options] private_key hash_method'
description = ('Signs a file, outputs the signature. Choose the hash '
'method from %s' % ', '.join(HASH_METHODS))
operation = 'sign'
operation_past = 'signature'
operation_progressive = 'Signing'
key_class = rsa.PrivateKey
expected_cli_args = 2
output_help = ('Name of the file to write the signature to. Written '
'to stdout if this option is not present.')
def perform_operation(self, indata, priv_key, cli_args):
'''Decrypts files.'''
hash_method = cli_args[1]
if hash_method not in HASH_METHODS:
raise SystemExit('Invalid hash method, choose one of %s' %
', '.join(HASH_METHODS))
return rsa.sign(indata, priv_key, hash_method)
class VerifyOperation(CryptoOperation):
'''Verify a signature.'''
keyname = 'public'
usage = 'usage: %%prog [options] private_key signature_file'
description = ('Verifies a signature, exits with status 0 upon success, '
'prints an error message and exits with status 1 upon error.')
operation = 'verify'
operation_past = 'verified'
operation_progressive = 'Verifying'
key_class = rsa.PublicKey
expected_cli_args = 2
has_output = False
def perform_operation(self, indata, pub_key, cli_args):
'''Decrypts files.'''
signature_file = cli_args[1]
with open(signature_file, 'rb') as sigfile:
signature = sigfile.read()
try:
rsa.verify(indata, signature, pub_key)
except rsa.VerificationError:
raise SystemExit('Verification failed.')
print('Verification OK', file=sys.stderr)
class BigfileOperation(CryptoOperation):
'''CryptoOperation that doesn't read the entire file into memory.'''
def __init__(self):
CryptoOperation.__init__(self)
self.file_objects = []
def __del__(self):
'''Closes any open file handles.'''
for fobj in self.file_objects:
fobj.close()
def __call__(self):
'''Runs the program.'''
(cli, cli_args) = self.parse_cli()
key = self.read_key(cli_args[0], cli.keyform)
# Get the file handles
infile = self.get_infile(cli.input)
outfile = self.get_outfile(cli.output)
# Call the operation
print(self.operation_progressive.title(), file=sys.stderr)
self.perform_operation(infile, outfile, key, cli_args)
def get_infile(self, inname):
'''Returns the input file object'''
if inname:
print('Reading input from %s' % inname, file=sys.stderr)
fobj = open(inname, 'rb')
self.file_objects.append(fobj)
else:
print('Reading input from stdin', file=sys.stderr)
fobj = sys.stdin
return fobj
def get_outfile(self, outname):
'''Returns the output file object'''
if outname:
print('Will write output to %s' % outname, file=sys.stderr)
fobj = open(outname, 'wb')
self.file_objects.append(fobj)
else:
print('Will write output to stdout', file=sys.stderr)
fobj = sys.stdout
return fobj
class EncryptBigfileOperation(BigfileOperation):
'''Encrypts a file to VARBLOCK format.'''
keyname = 'public'
description = ('Encrypts a file to an encrypted VARBLOCK file. The file '
'can be larger than the key length, but the output file is only '
'compatible with Python-RSA.')
operation = 'encrypt'
operation_past = 'encrypted'
operation_progressive = 'encrypting'
def perform_operation(self, infile, outfile, pub_key, cli_args=None):
'''Encrypts files to VARBLOCK.'''
return rsa.bigfile.encrypt_bigfile(infile, outfile, pub_key)
class DecryptBigfileOperation(BigfileOperation):
'''Decrypts a file in VARBLOCK format.'''
keyname = 'private'
description = ('Decrypts an encrypted VARBLOCK file that was encrypted '
'with pyrsa-encrypt-bigfile')
operation = 'decrypt'
operation_past = 'decrypted'
operation_progressive = 'decrypting'
key_class = rsa.PrivateKey
def perform_operation(self, infile, outfile, priv_key, cli_args=None):
'''Decrypts a VARBLOCK file.'''
return rsa.bigfile.decrypt_bigfile(infile, outfile, priv_key)
encrypt = EncryptOperation()
decrypt = DecryptOperation()
sign = SignOperation()
verify = VerifyOperation()
encrypt_bigfile = EncryptBigfileOperation()
decrypt_bigfile = DecryptBigfileOperation()

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# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Common functionality shared by several modules.'''
def bit_size(num):
'''
Number of bits needed to represent a integer excluding any prefix
0 bits.
As per definition from http://wiki.python.org/moin/BitManipulation and
to match the behavior of the Python 3 API.
Usage::
>>> bit_size(1023)
10
>>> bit_size(1024)
11
>>> bit_size(1025)
11
:param num:
Integer value. If num is 0, returns 0. Only the absolute value of the
number is considered. Therefore, signed integers will be abs(num)
before the number's bit length is determined.
:returns:
Returns the number of bits in the integer.
'''
if num == 0:
return 0
if num < 0:
num = -num
# Make sure this is an int and not a float.
num & 1
hex_num = "%x" % num
return ((len(hex_num) - 1) * 4) + {
'0':0, '1':1, '2':2, '3':2,
'4':3, '5':3, '6':3, '7':3,
'8':4, '9':4, 'a':4, 'b':4,
'c':4, 'd':4, 'e':4, 'f':4,
}[hex_num[0]]
def _bit_size(number):
'''
Returns the number of bits required to hold a specific long number.
'''
if number < 0:
raise ValueError('Only nonnegative numbers possible: %s' % number)
if number == 0:
return 0
# This works, even with very large numbers. When using math.log(number, 2),
# you'll get rounding errors and it'll fail.
bits = 0
while number:
bits += 1
number >>= 1
return bits
def byte_size(number):
'''
Returns the number of bytes required to hold a specific long number.
The number of bytes is rounded up.
Usage::
>>> byte_size(1 << 1023)
128
>>> byte_size((1 << 1024) - 1)
128
>>> byte_size(1 << 1024)
129
:param number:
An unsigned integer
:returns:
The number of bytes required to hold a specific long number.
'''
quanta, mod = divmod(bit_size(number), 8)
if mod or number == 0:
quanta += 1
return quanta
#return int(math.ceil(bit_size(number) / 8.0))
def extended_gcd(a, b):
'''Returns a tuple (r, i, j) such that r = gcd(a, b) = ia + jb
'''
# r = gcd(a,b) i = multiplicitive inverse of a mod b
# or j = multiplicitive inverse of b mod a
# Neg return values for i or j are made positive mod b or a respectively
# Iterateive Version is faster and uses much less stack space
x = 0
y = 1
lx = 1
ly = 0
oa = a #Remember original a/b to remove
ob = b #negative values from return results
while b != 0:
q = a // b
(a, b) = (b, a % b)
(x, lx) = ((lx - (q * x)),x)
(y, ly) = ((ly - (q * y)),y)
if (lx < 0): lx += ob #If neg wrap modulo orignal b
if (ly < 0): ly += oa #If neg wrap modulo orignal a
return (a, lx, ly) #Return only positive values
def inverse(x, n):
'''Returns x^-1 (mod n)
>>> inverse(7, 4)
3
>>> (inverse(143, 4) * 143) % 4
1
'''
(divider, inv, _) = extended_gcd(x, n)
if divider != 1:
raise ValueError("x (%d) and n (%d) are not relatively prime" % (x, n))
return inv
def crt(a_values, modulo_values):
'''Chinese Remainder Theorem.
Calculates x such that x = a[i] (mod m[i]) for each i.
:param a_values: the a-values of the above equation
:param modulo_values: the m-values of the above equation
:returns: x such that x = a[i] (mod m[i]) for each i
>>> crt([2, 3], [3, 5])
8
>>> crt([2, 3, 2], [3, 5, 7])
23
>>> crt([2, 3, 0], [7, 11, 15])
135
'''
m = 1
x = 0
for modulo in modulo_values:
m *= modulo
for (m_i, a_i) in zip(modulo_values, a_values):
M_i = m // m_i
inv = inverse(M_i, m_i)
x = (x + a_i * M_i * inv) % m
return x
if __name__ == '__main__':
import doctest
doctest.testmod()

58
rsa/core.py
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@ -1,58 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Core mathematical operations.
This is the actual core RSA implementation, which is only defined
mathematically on integers.
'''
from rsa._compat import is_integer
def assert_int(var, name):
if is_integer(var):
return
raise TypeError('%s should be an integer, not %s' % (name, var.__class__))
def encrypt_int(message, ekey, n):
'''Encrypts a message using encryption key 'ekey', working modulo n'''
assert_int(message, 'message')
assert_int(ekey, 'ekey')
assert_int(n, 'n')
if message < 0:
raise ValueError('Only non-negative numbers are supported')
if message > n:
raise OverflowError("The message %i is too long for n=%i" % (message, n))
return pow(message, ekey, n)
def decrypt_int(cyphertext, dkey, n):
'''Decrypts a cypher text using the decryption key 'dkey', working
modulo n'''
assert_int(cyphertext, 'cyphertext')
assert_int(dkey, 'dkey')
assert_int(n, 'n')
message = pow(cyphertext, dkey, n)
return message

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rsa/key.py
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@ -1,581 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''RSA key generation code.
Create new keys with the newkeys() function. It will give you a PublicKey and a
PrivateKey object.
Loading and saving keys requires the pyasn1 module. This module is imported as
late as possible, such that other functionality will remain working in absence
of pyasn1.
'''
import logging
from rsa._compat import b
import rsa.prime
import rsa.pem
import rsa.common
log = logging.getLogger(__name__)
class AbstractKey(object):
'''Abstract superclass for private and public keys.'''
@classmethod
def load_pkcs1(cls, keyfile, format='PEM'):
r'''Loads a key in PKCS#1 DER or PEM format.
:param keyfile: contents of a DER- or PEM-encoded file that contains
the public key.
:param format: the format of the file to load; 'PEM' or 'DER'
:return: a PublicKey object
'''
methods = {
'PEM': cls._load_pkcs1_pem,
'DER': cls._load_pkcs1_der,
}
if format not in methods:
formats = ', '.join(sorted(methods.keys()))
raise ValueError('Unsupported format: %r, try one of %s' % (format,
formats))
method = methods[format]
return method(keyfile)
def save_pkcs1(self, format='PEM'):
'''Saves the public key in PKCS#1 DER or PEM format.
:param format: the format to save; 'PEM' or 'DER'
:returns: the DER- or PEM-encoded public key.
'''
methods = {
'PEM': self._save_pkcs1_pem,
'DER': self._save_pkcs1_der,
}
if format not in methods:
formats = ', '.join(sorted(methods.keys()))
raise ValueError('Unsupported format: %r, try one of %s' % (format,
formats))
method = methods[format]
return method()
class PublicKey(AbstractKey):
'''Represents a public RSA key.
This key is also known as the 'encryption key'. It contains the 'n' and 'e'
values.
Supports attributes as well as dictionary-like access. Attribute accesss is
faster, though.
>>> PublicKey(5, 3)
PublicKey(5, 3)
>>> key = PublicKey(5, 3)
>>> key.n
5
>>> key['n']
5
>>> key.e
3
>>> key['e']
3
'''
__slots__ = ('n', 'e')
def __init__(self, n, e):
self.n = n
self.e = e
def __getitem__(self, key):
return getattr(self, key)
def __repr__(self):
return 'PublicKey(%i, %i)' % (self.n, self.e)
def __eq__(self, other):
if other is None:
return False
if not isinstance(other, PublicKey):
return False
return self.n == other.n and self.e == other.e
def __ne__(self, other):
return not (self == other)
@classmethod
def _load_pkcs1_der(cls, keyfile):
r'''Loads a key in PKCS#1 DER format.
@param keyfile: contents of a DER-encoded file that contains the public
key.
@return: a PublicKey object
First let's construct a DER encoded key:
>>> import base64
>>> b64der = 'MAwCBQCNGmYtAgMBAAE='
>>> der = base64.decodestring(b64der)
This loads the file:
>>> PublicKey._load_pkcs1_der(der)
PublicKey(2367317549, 65537)
'''
from pyasn1.codec.der import decoder
(priv, _) = decoder.decode(keyfile)
# ASN.1 contents of DER encoded public key:
#
# RSAPublicKey ::= SEQUENCE {
# modulus INTEGER, -- n
# publicExponent INTEGER, -- e
as_ints = tuple(int(x) for x in priv)
return cls(*as_ints)
def _save_pkcs1_der(self):
'''Saves the public key in PKCS#1 DER format.
@returns: the DER-encoded public key.
'''
from pyasn1.type import univ, namedtype
from pyasn1.codec.der import encoder
class AsnPubKey(univ.Sequence):
componentType = namedtype.NamedTypes(
namedtype.NamedType('modulus', univ.Integer()),
namedtype.NamedType('publicExponent', univ.Integer()),
)
# Create the ASN object
asn_key = AsnPubKey()
asn_key.setComponentByName('modulus', self.n)
asn_key.setComponentByName('publicExponent', self.e)
return encoder.encode(asn_key)
@classmethod
def _load_pkcs1_pem(cls, keyfile):
'''Loads a PKCS#1 PEM-encoded public key file.
The contents of the file before the "-----BEGIN RSA PUBLIC KEY-----" and
after the "-----END RSA PUBLIC KEY-----" lines is ignored.
@param keyfile: contents of a PEM-encoded file that contains the public
key.
@return: a PublicKey object
'''
der = rsa.pem.load_pem(keyfile, 'RSA PUBLIC KEY')
return cls._load_pkcs1_der(der)
def _save_pkcs1_pem(self):
'''Saves a PKCS#1 PEM-encoded public key file.
@return: contents of a PEM-encoded file that contains the public key.
'''
der = self._save_pkcs1_der()
return rsa.pem.save_pem(der, 'RSA PUBLIC KEY')
class PrivateKey(AbstractKey):
'''Represents a private RSA key.
This key is also known as the 'decryption key'. It contains the 'n', 'e',
'd', 'p', 'q' and other values.
Supports attributes as well as dictionary-like access. Attribute accesss is
faster, though.
>>> PrivateKey(3247, 65537, 833, 191, 17)
PrivateKey(3247, 65537, 833, 191, 17)
exp1, exp2 and coef don't have to be given, they will be calculated:
>>> pk = PrivateKey(3727264081, 65537, 3349121513, 65063, 57287)
>>> pk.exp1
55063
>>> pk.exp2
10095
>>> pk.coef
50797
If you give exp1, exp2 or coef, they will be used as-is:
>>> pk = PrivateKey(1, 2, 3, 4, 5, 6, 7, 8)
>>> pk.exp1
6
>>> pk.exp2
7
>>> pk.coef
8
'''
__slots__ = ('n', 'e', 'd', 'p', 'q', 'exp1', 'exp2', 'coef')
def __init__(self, n, e, d, p, q, exp1=None, exp2=None, coef=None):
self.n = n
self.e = e
self.d = d
self.p = p
self.q = q
# Calculate the other values if they aren't supplied
if exp1 is None:
self.exp1 = int(d % (p - 1))
else:
self.exp1 = exp1
if exp1 is None:
self.exp2 = int(d % (q - 1))
else:
self.exp2 = exp2
if coef is None:
self.coef = rsa.common.inverse(q, p)
else:
self.coef = coef
def __getitem__(self, key):
return getattr(self, key)
def __repr__(self):
return 'PrivateKey(%(n)i, %(e)i, %(d)i, %(p)i, %(q)i)' % self
def __eq__(self, other):
if other is None:
return False
if not isinstance(other, PrivateKey):
return False
return (self.n == other.n and
self.e == other.e and
self.d == other.d and
self.p == other.p and
self.q == other.q and
self.exp1 == other.exp1 and
self.exp2 == other.exp2 and
self.coef == other.coef)
def __ne__(self, other):
return not (self == other)
@classmethod
def _load_pkcs1_der(cls, keyfile):
r'''Loads a key in PKCS#1 DER format.
@param keyfile: contents of a DER-encoded file that contains the private
key.
@return: a PrivateKey object
First let's construct a DER encoded key:
>>> import base64
>>> b64der = 'MC4CAQACBQDeKYlRAgMBAAECBQDHn4npAgMA/icCAwDfxwIDANcXAgInbwIDAMZt'
>>> der = base64.decodestring(b64der)
This loads the file:
>>> PrivateKey._load_pkcs1_der(der)
PrivateKey(3727264081, 65537, 3349121513, 65063, 57287)
'''
from pyasn1.codec.der import decoder
(priv, _) = decoder.decode(keyfile)
# ASN.1 contents of DER encoded private key:
#
# RSAPrivateKey ::= SEQUENCE {
# version Version,
# modulus INTEGER, -- n
# publicExponent INTEGER, -- e
# privateExponent INTEGER, -- d
# prime1 INTEGER, -- p
# prime2 INTEGER, -- q
# exponent1 INTEGER, -- d mod (p-1)
# exponent2 INTEGER, -- d mod (q-1)
# coefficient INTEGER, -- (inverse of q) mod p
# otherPrimeInfos OtherPrimeInfos OPTIONAL
# }
if priv[0] != 0:
raise ValueError('Unable to read this file, version %s != 0' % priv[0])
as_ints = tuple(int(x) for x in priv[1:9])
return cls(*as_ints)
def _save_pkcs1_der(self):
'''Saves the private key in PKCS#1 DER format.
@returns: the DER-encoded private key.
'''
from pyasn1.type import univ, namedtype
from pyasn1.codec.der import encoder
class AsnPrivKey(univ.Sequence):
componentType = namedtype.NamedTypes(
namedtype.NamedType('version', univ.Integer()),
namedtype.NamedType('modulus', univ.Integer()),
namedtype.NamedType('publicExponent', univ.Integer()),
namedtype.NamedType('privateExponent', univ.Integer()),
namedtype.NamedType('prime1', univ.Integer()),
namedtype.NamedType('prime2', univ.Integer()),
namedtype.NamedType('exponent1', univ.Integer()),
namedtype.NamedType('exponent2', univ.Integer()),
namedtype.NamedType('coefficient', univ.Integer()),
)
# Create the ASN object
asn_key = AsnPrivKey()
asn_key.setComponentByName('version', 0)
asn_key.setComponentByName('modulus', self.n)
asn_key.setComponentByName('publicExponent', self.e)
asn_key.setComponentByName('privateExponent', self.d)
asn_key.setComponentByName('prime1', self.p)
asn_key.setComponentByName('prime2', self.q)
asn_key.setComponentByName('exponent1', self.exp1)
asn_key.setComponentByName('exponent2', self.exp2)
asn_key.setComponentByName('coefficient', self.coef)
return encoder.encode(asn_key)
@classmethod
def _load_pkcs1_pem(cls, keyfile):
'''Loads a PKCS#1 PEM-encoded private key file.
The contents of the file before the "-----BEGIN RSA PRIVATE KEY-----" and
after the "-----END RSA PRIVATE KEY-----" lines is ignored.
@param keyfile: contents of a PEM-encoded file that contains the private
key.
@return: a PrivateKey object
'''
der = rsa.pem.load_pem(keyfile, b('RSA PRIVATE KEY'))
return cls._load_pkcs1_der(der)
def _save_pkcs1_pem(self):
'''Saves a PKCS#1 PEM-encoded private key file.
@return: contents of a PEM-encoded file that contains the private key.
'''
der = self._save_pkcs1_der()
return rsa.pem.save_pem(der, b('RSA PRIVATE KEY'))
def find_p_q(nbits, getprime_func=rsa.prime.getprime, accurate=True):
''''Returns a tuple of two different primes of nbits bits each.
The resulting p * q has exacty 2 * nbits bits, and the returned p and q
will not be equal.
:param nbits: the number of bits in each of p and q.
:param getprime_func: the getprime function, defaults to
:py:func:`rsa.prime.getprime`.
*Introduced in Python-RSA 3.1*
:param accurate: whether to enable accurate mode or not.
:returns: (p, q), where p > q
>>> (p, q) = find_p_q(128)
>>> from rsa import common
>>> common.bit_size(p * q)
256
When not in accurate mode, the number of bits can be slightly less
>>> (p, q) = find_p_q(128, accurate=False)
>>> from rsa import common
>>> common.bit_size(p * q) <= 256
True
>>> common.bit_size(p * q) > 240
True
'''
total_bits = nbits * 2
# Make sure that p and q aren't too close or the factoring programs can
# factor n.
shift = nbits // 16
pbits = nbits + shift
qbits = nbits - shift
# Choose the two initial primes
log.debug('find_p_q(%i): Finding p', nbits)
p = getprime_func(pbits)
log.debug('find_p_q(%i): Finding q', nbits)
q = getprime_func(qbits)
def is_acceptable(p, q):
'''Returns True iff p and q are acceptable:
- p and q differ
- (p * q) has the right nr of bits (when accurate=True)
'''
if p == q:
return False
if not accurate:
return True
# Make sure we have just the right amount of bits
found_size = rsa.common.bit_size(p * q)
return total_bits == found_size
# Keep choosing other primes until they match our requirements.
change_p = False
while not is_acceptable(p, q):
# Change p on one iteration and q on the other
if change_p:
p = getprime_func(pbits)
else:
q = getprime_func(qbits)
change_p = not change_p
# We want p > q as described on
# http://www.di-mgt.com.au/rsa_alg.html#crt
return (max(p, q), min(p, q))
def calculate_keys(p, q, nbits):
'''Calculates an encryption and a decryption key given p and q, and
returns them as a tuple (e, d)
'''
phi_n = (p - 1) * (q - 1)
# A very common choice for e is 65537
e = 65537
try:
d = rsa.common.inverse(e, phi_n)
except ValueError:
raise ValueError("e (%d) and phi_n (%d) are not relatively prime" %
(e, phi_n))
if (e * d) % phi_n != 1:
raise ValueError("e (%d) and d (%d) are not mult. inv. modulo "
"phi_n (%d)" % (e, d, phi_n))
return (e, d)
def gen_keys(nbits, getprime_func, accurate=True):
'''Generate RSA keys of nbits bits. Returns (p, q, e, d).
Note: this can take a long time, depending on the key size.
:param nbits: the total number of bits in ``p`` and ``q``. Both ``p`` and
``q`` will use ``nbits/2`` bits.
:param getprime_func: either :py:func:`rsa.prime.getprime` or a function
with similar signature.
'''
(p, q) = find_p_q(nbits // 2, getprime_func, accurate)
(e, d) = calculate_keys(p, q, nbits // 2)
return (p, q, e, d)
def newkeys(nbits, accurate=True, poolsize=1):
'''Generates public and private keys, and returns them as (pub, priv).
The public key is also known as the 'encryption key', and is a
:py:class:`rsa.PublicKey` object. The private key is also known as the
'decryption key' and is a :py:class:`rsa.PrivateKey` object.
:param nbits: the number of bits required to store ``n = p*q``.
:param accurate: when True, ``n`` will have exactly the number of bits you
asked for. However, this makes key generation much slower. When False,
`n`` may have slightly less bits.
:param poolsize: the number of processes to use to generate the prime
numbers. If set to a number > 1, a parallel algorithm will be used.
This requires Python 2.6 or newer.
:returns: a tuple (:py:class:`rsa.PublicKey`, :py:class:`rsa.PrivateKey`)
The ``poolsize`` parameter was added in *Python-RSA 3.1* and requires
Python 2.6 or newer.
'''
if nbits < 16:
raise ValueError('Key too small')
if poolsize < 1:
raise ValueError('Pool size (%i) should be >= 1' % poolsize)
# Determine which getprime function to use
if poolsize > 1:
from rsa import parallel
import functools
getprime_func = functools.partial(parallel.getprime, poolsize=poolsize)
else: getprime_func = rsa.prime.getprime
# Generate the key components
(p, q, e, d) = gen_keys(nbits, getprime_func)
# Create the key objects
n = p * q
return (
PublicKey(n, e),
PrivateKey(n, e, d, p, q)
)
__all__ = ['PublicKey', 'PrivateKey', 'newkeys']
if __name__ == '__main__':
import doctest
try:
for count in range(100):
(failures, tests) = doctest.testmod()
if failures:
break
if (count and count % 10 == 0) or count == 1:
print('%i times' % count)
except KeyboardInterrupt:
print('Aborted')
else:
print('Doctests done')

94
rsa/parallel.py
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@ -1,94 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Functions for parallel computation on multiple cores.
Introduced in Python-RSA 3.1.
.. note::
Requires Python 2.6 or newer.
'''
from __future__ import print_function
import multiprocessing as mp
import rsa.prime
import rsa.randnum
def _find_prime(nbits, pipe):
while True:
integer = rsa.randnum.read_random_int(nbits)
# Make sure it's odd
integer |= 1
# Test for primeness
if rsa.prime.is_prime(integer):
pipe.send(integer)
return
def getprime(nbits, poolsize):
'''Returns a prime number that can be stored in 'nbits' bits.
Works in multiple threads at the same time.
>>> p = getprime(128, 3)
>>> rsa.prime.is_prime(p-1)
False
>>> rsa.prime.is_prime(p)
True
>>> rsa.prime.is_prime(p+1)
False
>>> from rsa import common
>>> common.bit_size(p) == 128
True
'''
(pipe_recv, pipe_send) = mp.Pipe(duplex=False)
# Create processes
procs = [mp.Process(target=_find_prime, args=(nbits, pipe_send))
for _ in range(poolsize)]
[p.start() for p in procs]
result = pipe_recv.recv()
[p.terminate() for p in procs]
return result
__all__ = ['getprime']
if __name__ == '__main__':
print('Running doctests 1000x or until failure')
import doctest
for count in range(100):
(failures, tests) = doctest.testmod()
if failures:
break
if count and count % 10 == 0:
print('%i times' % count)
print('Doctests done')

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# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Functions that load and write PEM-encoded files.'''
import base64
from rsa._compat import b, is_bytes
def _markers(pem_marker):
'''
Returns the start and end PEM markers
'''
if is_bytes(pem_marker):
pem_marker = pem_marker.decode('utf-8')
return (b('-----BEGIN %s-----' % pem_marker),
b('-----END %s-----' % pem_marker))
def load_pem(contents, pem_marker):
'''Loads a PEM file.
@param contents: the contents of the file to interpret
@param pem_marker: the marker of the PEM content, such as 'RSA PRIVATE KEY'
when your file has '-----BEGIN RSA PRIVATE KEY-----' and
'-----END RSA PRIVATE KEY-----' markers.
@return the base64-decoded content between the start and end markers.
@raise ValueError: when the content is invalid, for example when the start
marker cannot be found.
'''
(pem_start, pem_end) = _markers(pem_marker)
pem_lines = []
in_pem_part = False
for line in contents.splitlines():
line = line.strip()
# Skip empty lines
if not line:
continue
# Handle start marker
if line == pem_start:
if in_pem_part:
raise ValueError('Seen start marker "%s" twice' % pem_start)
in_pem_part = True
continue
# Skip stuff before first marker
if not in_pem_part:
continue
# Handle end marker
if in_pem_part and line == pem_end:
in_pem_part = False
break
# Load fields
if b(':') in line:
continue
pem_lines.append(line)
# Do some sanity checks
if not pem_lines:
raise ValueError('No PEM start marker "%s" found' % pem_start)
if in_pem_part:
raise ValueError('No PEM end marker "%s" found' % pem_end)
# Base64-decode the contents
pem = b('').join(pem_lines)
return base64.decodestring(pem)
def save_pem(contents, pem_marker):
'''Saves a PEM file.
@param contents: the contents to encode in PEM format
@param pem_marker: the marker of the PEM content, such as 'RSA PRIVATE KEY'
when your file has '-----BEGIN RSA PRIVATE KEY-----' and
'-----END RSA PRIVATE KEY-----' markers.
@return the base64-encoded content between the start and end markers.
'''
(pem_start, pem_end) = _markers(pem_marker)
b64 = base64.encodestring(contents).replace(b('\n'), b(''))
pem_lines = [pem_start]
for block_start in range(0, len(b64), 64):
block = b64[block_start:block_start + 64]
pem_lines.append(block)
pem_lines.append(pem_end)
pem_lines.append(b(''))
return b('\n').join(pem_lines)

389
rsa/pkcs1.py
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@ -1,389 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Functions for PKCS#1 version 1.5 encryption and signing
This module implements certain functionality from PKCS#1 version 1.5. For a
very clear example, read http://www.di-mgt.com.au/rsa_alg.html#pkcs1schemes
At least 8 bytes of random padding is used when encrypting a message. This makes
these methods much more secure than the ones in the ``rsa`` module.
WARNING: this module leaks information when decryption or verification fails.
The exceptions that are raised contain the Python traceback information, which
can be used to deduce where in the process the failure occurred. DO NOT PASS
SUCH INFORMATION to your users.
'''
import hashlib
import os
from rsa._compat import b
from rsa import common, transform, core, varblock
# ASN.1 codes that describe the hash algorithm used.
HASH_ASN1 = {
'MD5': b('\x30\x20\x30\x0c\x06\x08\x2a\x86\x48\x86\xf7\x0d\x02\x05\x05\x00\x04\x10'),
'SHA-1': b('\x30\x21\x30\x09\x06\x05\x2b\x0e\x03\x02\x1a\x05\x00\x04\x14'),
'SHA-256': b('\x30\x31\x30\x0d\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x01\x05\x00\x04\x20'),
'SHA-384': b('\x30\x41\x30\x0d\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x02\x05\x00\x04\x30'),
'SHA-512': b('\x30\x51\x30\x0d\x06\x09\x60\x86\x48\x01\x65\x03\x04\x02\x03\x05\x00\x04\x40'),
}
HASH_METHODS = {
'MD5': hashlib.md5,
'SHA-1': hashlib.sha1,
'SHA-256': hashlib.sha256,
'SHA-384': hashlib.sha384,
'SHA-512': hashlib.sha512,
}
class CryptoError(Exception):
'''Base class for all exceptions in this module.'''
class DecryptionError(CryptoError):
'''Raised when decryption fails.'''
class VerificationError(CryptoError):
'''Raised when verification fails.'''
def _pad_for_encryption(message, target_length):
r'''Pads the message for encryption, returning the padded message.
:return: 00 02 RANDOM_DATA 00 MESSAGE
>>> block = _pad_for_encryption('hello', 16)
>>> len(block)
16
>>> block[0:2]
'\x00\x02'
>>> block[-6:]
'\x00hello'
'''
max_msglength = target_length - 11
msglength = len(message)
if msglength > max_msglength:
raise OverflowError('%i bytes needed for message, but there is only'
' space for %i' % (msglength, max_msglength))
# Get random padding
padding = b('')
padding_length = target_length - msglength - 3
# We remove 0-bytes, so we'll end up with less padding than we've asked for,
# so keep adding data until we're at the correct length.
while len(padding) < padding_length:
needed_bytes = padding_length - len(padding)
# Always read at least 8 bytes more than we need, and trim off the rest
# after removing the 0-bytes. This increases the chance of getting
# enough bytes, especially when needed_bytes is small
new_padding = os.urandom(needed_bytes + 5)
new_padding = new_padding.replace(b('\x00'), b(''))
padding = padding + new_padding[:needed_bytes]
assert len(padding) == padding_length
return b('').join([b('\x00\x02'),
padding,
b('\x00'),
message])
def _pad_for_signing(message, target_length):
r'''Pads the message for signing, returning the padded message.
The padding is always a repetition of FF bytes.
:return: 00 01 PADDING 00 MESSAGE
>>> block = _pad_for_signing('hello', 16)
>>> len(block)
16
>>> block[0:2]
'\x00\x01'
>>> block[-6:]
'\x00hello'
>>> block[2:-6]
'\xff\xff\xff\xff\xff\xff\xff\xff'
'''
max_msglength = target_length - 11
msglength = len(message)
if msglength > max_msglength:
raise OverflowError('%i bytes needed for message, but there is only'
' space for %i' % (msglength, max_msglength))
padding_length = target_length - msglength - 3
return b('').join([b('\x00\x01'),
padding_length * b('\xff'),
b('\x00'),
message])
def encrypt(message, pub_key):
'''Encrypts the given message using PKCS#1 v1.5
:param message: the message to encrypt. Must be a byte string no longer than
``k-11`` bytes, where ``k`` is the number of bytes needed to encode
the ``n`` component of the public key.
:param pub_key: the :py:class:`rsa.PublicKey` to encrypt with.
:raise OverflowError: when the message is too large to fit in the padded
block.
>>> from rsa import key, common
>>> (pub_key, priv_key) = key.newkeys(256)
>>> message = 'hello'
>>> crypto = encrypt(message, pub_key)
The crypto text should be just as long as the public key 'n' component:
>>> len(crypto) == common.byte_size(pub_key.n)
True
'''
keylength = common.byte_size(pub_key.n)
padded = _pad_for_encryption(message, keylength)
payload = transform.bytes2int(padded)
encrypted = core.encrypt_int(payload, pub_key.e, pub_key.n)
block = transform.int2bytes(encrypted, keylength)
return block
def decrypt(crypto, priv_key):
r'''Decrypts the given message using PKCS#1 v1.5
The decryption is considered 'failed' when the resulting cleartext doesn't
start with the bytes 00 02, or when the 00 byte between the padding and
the message cannot be found.
:param crypto: the crypto text as returned by :py:func:`rsa.encrypt`
:param priv_key: the :py:class:`rsa.PrivateKey` to decrypt with.
:raise DecryptionError: when the decryption fails. No details are given as
to why the code thinks the decryption fails, as this would leak
information about the private key.
>>> import rsa
>>> (pub_key, priv_key) = rsa.newkeys(256)
It works with strings:
>>> crypto = encrypt('hello', pub_key)
>>> decrypt(crypto, priv_key)
'hello'
And with binary data:
>>> crypto = encrypt('\x00\x00\x00\x00\x01', pub_key)
>>> decrypt(crypto, priv_key)
'\x00\x00\x00\x00\x01'
Altering the encrypted information will *likely* cause a
:py:class:`rsa.pkcs1.DecryptionError`. If you want to be *sure*, use
:py:func:`rsa.sign`.
.. warning::
Never display the stack trace of a
:py:class:`rsa.pkcs1.DecryptionError` exception. It shows where in the
code the exception occurred, and thus leaks information about the key.
It's only a tiny bit of information, but every bit makes cracking the
keys easier.
>>> crypto = encrypt('hello', pub_key)
>>> crypto = crypto[0:5] + 'X' + crypto[6:] # change a byte
>>> decrypt(crypto, priv_key)
Traceback (most recent call last):
...
DecryptionError: Decryption failed
'''
blocksize = common.byte_size(priv_key.n)
encrypted = transform.bytes2int(crypto)
decrypted = core.decrypt_int(encrypted, priv_key.d, priv_key.n)
cleartext = transform.int2bytes(decrypted, blocksize)
# If we can't find the cleartext marker, decryption failed.
if cleartext[0:2] != b('\x00\x02'):
raise DecryptionError('Decryption failed')
# Find the 00 separator between the padding and the message
try:
sep_idx = cleartext.index(b('\x00'), 2)
except ValueError:
raise DecryptionError('Decryption failed')
return cleartext[sep_idx+1:]
def sign(message, priv_key, hash):
'''Signs the message with the private key.
Hashes the message, then signs the hash with the given key. This is known
as a "detached signature", because the message itself isn't altered.
:param message: the message to sign. Can be an 8-bit string or a file-like
object. If ``message`` has a ``read()`` method, it is assumed to be a
file-like object.
:param priv_key: the :py:class:`rsa.PrivateKey` to sign with
:param hash: the hash method used on the message. Use 'MD5', 'SHA-1',
'SHA-256', 'SHA-384' or 'SHA-512'.
:return: a message signature block.
:raise OverflowError: if the private key is too small to contain the
requested hash.
'''
# Get the ASN1 code for this hash method
if hash not in HASH_ASN1:
raise ValueError('Invalid hash method: %s' % hash)
asn1code = HASH_ASN1[hash]
# Calculate the hash
hash = _hash(message, hash)
# Encrypt the hash with the private key
cleartext = asn1code + hash
keylength = common.byte_size(priv_key.n)
padded = _pad_for_signing(cleartext, keylength)
payload = transform.bytes2int(padded)
encrypted = core.encrypt_int(payload, priv_key.d, priv_key.n)
block = transform.int2bytes(encrypted, keylength)
return block
def verify(message, signature, pub_key):
'''Verifies that the signature matches the message.
The hash method is detected automatically from the signature.
:param message: the signed message. Can be an 8-bit string or a file-like
object. If ``message`` has a ``read()`` method, it is assumed to be a
file-like object.
:param signature: the signature block, as created with :py:func:`rsa.sign`.
:param pub_key: the :py:class:`rsa.PublicKey` of the person signing the message.
:raise VerificationError: when the signature doesn't match the message.
.. warning::
Never display the stack trace of a
:py:class:`rsa.pkcs1.VerificationError` exception. It shows where in
the code the exception occurred, and thus leaks information about the
key. It's only a tiny bit of information, but every bit makes cracking
the keys easier.
'''
blocksize = common.byte_size(pub_key.n)
encrypted = transform.bytes2int(signature)
decrypted = core.decrypt_int(encrypted, pub_key.e, pub_key.n)
clearsig = transform.int2bytes(decrypted, blocksize)
# If we can't find the signature marker, verification failed.
if clearsig[0:2] != b('\x00\x01'):
raise VerificationError('Verification failed')
# Find the 00 separator between the padding and the payload
try:
sep_idx = clearsig.index(b('\x00'), 2)
except ValueError:
raise VerificationError('Verification failed')
# Get the hash and the hash method
(method_name, signature_hash) = _find_method_hash(clearsig[sep_idx+1:])
message_hash = _hash(message, method_name)
# Compare the real hash to the hash in the signature
if message_hash != signature_hash:
raise VerificationError('Verification failed')
def _hash(message, method_name):
'''Returns the message digest.
:param message: the signed message. Can be an 8-bit string or a file-like
object. If ``message`` has a ``read()`` method, it is assumed to be a
file-like object.
:param method_name: the hash method, must be a key of
:py:const:`HASH_METHODS`.
'''
if method_name not in HASH_METHODS:
raise ValueError('Invalid hash method: %s' % method_name)
method = HASH_METHODS[method_name]
hasher = method()
if hasattr(message, 'read') and hasattr(message.read, '__call__'):
# read as 1K blocks
for block in varblock.yield_fixedblocks(message, 1024):
hasher.update(block)
else:
# hash the message object itself.
hasher.update(message)
return hasher.digest()
def _find_method_hash(method_hash):
'''Finds the hash method and the hash itself.
:param method_hash: ASN1 code for the hash method concatenated with the
hash itself.
:return: tuple (method, hash) where ``method`` is the used hash method, and
``hash`` is the hash itself.
:raise VerificationFailed: when the hash method cannot be found
'''
for (hashname, asn1code) in HASH_ASN1.items():
if not method_hash.startswith(asn1code):
continue
return (hashname, method_hash[len(asn1code):])
raise VerificationError('Verification failed')
__all__ = ['encrypt', 'decrypt', 'sign', 'verify',
'DecryptionError', 'VerificationError', 'CryptoError']
if __name__ == '__main__':
print('Running doctests 1000x or until failure')
import doctest
for count in range(1000):
(failures, tests) = doctest.testmod()
if failures:
break
if count and count % 100 == 0:
print('%i times' % count)
print('Doctests done')

166
rsa/prime.py
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@ -1,166 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Numerical functions related to primes.
Implementation based on the book Algorithm Design by Michael T. Goodrich and
Roberto Tamassia, 2002.
'''
__all__ = [ 'getprime', 'are_relatively_prime']
import rsa.randnum
def gcd(p, q):
'''Returns the greatest common divisor of p and q
>>> gcd(48, 180)
12
'''
while q != 0:
if p < q: (p,q) = (q,p)
(p,q) = (q, p % q)
return p
def jacobi(a, b):
'''Calculates the value of the Jacobi symbol (a/b) where both a and b are
positive integers, and b is odd
:returns: -1, 0 or 1
'''
assert a > 0
assert b > 0
if a == 0: return 0
result = 1
while a > 1:
if a & 1:
if ((a-1)*(b-1) >> 2) & 1:
result = -result
a, b = b % a, a
else:
if (((b * b) - 1) >> 3) & 1:
result = -result
a >>= 1
if a == 0: return 0
return result
def jacobi_witness(x, n):
'''Returns False if n is an Euler pseudo-prime with base x, and
True otherwise.
'''
j = jacobi(x, n) % n
f = pow(x, n >> 1, n)
if j == f: return False
return True
def randomized_primality_testing(n, k):
'''Calculates whether n is composite (which is always correct) or
prime (which is incorrect with error probability 2**-k)
Returns False if the number is composite, and True if it's
probably prime.
'''
# 50% of Jacobi-witnesses can report compositness of non-prime numbers
# The implemented algorithm using the Jacobi witness function has error
# probability q <= 0.5, according to Goodrich et. al
#
# q = 0.5
# t = int(math.ceil(k / log(1 / q, 2)))
# So t = k / log(2, 2) = k / 1 = k
# this means we can use range(k) rather than range(t)
for _ in range(k):
x = rsa.randnum.randint(n-1)
if jacobi_witness(x, n): return False
return True
def is_prime(number):
'''Returns True if the number is prime, and False otherwise.
>>> is_prime(42)
False
>>> is_prime(41)
True
'''
return randomized_primality_testing(number, 6)
def getprime(nbits):
'''Returns a prime number that can be stored in 'nbits' bits.
>>> p = getprime(128)
>>> is_prime(p-1)
False
>>> is_prime(p)
True
>>> is_prime(p+1)
False
>>> from rsa import common
>>> common.bit_size(p) == 128
True
'''
while True:
integer = rsa.randnum.read_random_int(nbits)
# Make sure it's odd
integer |= 1
# Test for primeness
if is_prime(integer):
return integer
# Retry if not prime
def are_relatively_prime(a, b):
'''Returns True if a and b are relatively prime, and False if they
are not.
>>> are_relatively_prime(2, 3)
1
>>> are_relatively_prime(2, 4)
0
'''
d = gcd(a, b)
return (d == 1)
if __name__ == '__main__':
print('Running doctests 1000x or until failure')
import doctest
for count in range(1000):
(failures, tests) = doctest.testmod()
if failures:
break
if count and count % 100 == 0:
print('%i times' % count)
print('Doctests done')

85
rsa/randnum.py
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@ -1,85 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Functions for generating random numbers.'''
# Source inspired by code by Yesudeep Mangalapilly <yesudeep@gmail.com>
import os
from rsa import common, transform
from rsa._compat import byte
def read_random_bits(nbits):
'''Reads 'nbits' random bits.
If nbits isn't a whole number of bytes, an extra byte will be appended with
only the lower bits set.
'''
nbytes, rbits = divmod(nbits, 8)
# Get the random bytes
randomdata = os.urandom(nbytes)
# Add the remaining random bits
if rbits > 0:
randomvalue = ord(os.urandom(1))
randomvalue >>= (8 - rbits)
randomdata = byte(randomvalue) + randomdata
return randomdata
def read_random_int(nbits):
'''Reads a random integer of approximately nbits bits.
'''
randomdata = read_random_bits(nbits)
value = transform.bytes2int(randomdata)
# Ensure that the number is large enough to just fill out the required
# number of bits.
value |= 1 << (nbits - 1)
return value
def randint(maxvalue):
'''Returns a random integer x with 1 <= x <= maxvalue
May take a very long time in specific situations. If maxvalue needs N bits
to store, the closer maxvalue is to (2 ** N) - 1, the faster this function
is.
'''
bit_size = common.bit_size(maxvalue)
tries = 0
while True:
value = read_random_int(bit_size)
if value <= maxvalue:
break
if tries and tries % 10 == 0:
# After a lot of tries to get the right number of bits but still
# smaller than maxvalue, decrease the number of bits by 1. That'll
# dramatically increase the chances to get a large enough number.
bit_size -= 1
tries += 1
return value

220
rsa/transform.py
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@ -1,220 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Data transformation functions.
From bytes to a number, number to bytes, etc.
'''
from __future__ import absolute_import
try:
# We'll use psyco if available on 32-bit architectures to speed up code.
# Using psyco (if available) cuts down the execution time on Python 2.5
# at least by half.
import psyco
psyco.full()
except ImportError:
pass
import binascii
from struct import pack
from rsa import common
from rsa._compat import is_integer, b, byte, get_word_alignment, ZERO_BYTE, EMPTY_BYTE
def bytes2int(raw_bytes):
r'''Converts a list of bytes or an 8-bit string to an integer.
When using unicode strings, encode it to some encoding like UTF8 first.
>>> (((128 * 256) + 64) * 256) + 15
8405007
>>> bytes2int('\x80@\x0f')
8405007
'''
return int(binascii.hexlify(raw_bytes), 16)
def _int2bytes(number, block_size=None):
r'''Converts a number to a string of bytes.
Usage::
>>> _int2bytes(123456789)
'\x07[\xcd\x15'
>>> bytes2int(_int2bytes(123456789))
123456789
>>> _int2bytes(123456789, 6)
'\x00\x00\x07[\xcd\x15'
>>> bytes2int(_int2bytes(123456789, 128))
123456789
>>> _int2bytes(123456789, 3)
Traceback (most recent call last):
...
OverflowError: Needed 4 bytes for number, but block size is 3
@param number: the number to convert
@param block_size: the number of bytes to output. If the number encoded to
bytes is less than this, the block will be zero-padded. When not given,
the returned block is not padded.
@throws OverflowError when block_size is given and the number takes up more
bytes than fit into the block.
'''
# Type checking
if not is_integer(number):
raise TypeError("You must pass an integer for 'number', not %s" %
number.__class__)
if number < 0:
raise ValueError('Negative numbers cannot be used: %i' % number)
# Do some bounds checking
if number == 0:
needed_bytes = 1
raw_bytes = [ZERO_BYTE]
else:
needed_bytes = common.byte_size(number)
raw_bytes = []
# You cannot compare None > 0 in Python 3x. It will fail with a TypeError.
if block_size and block_size > 0:
if needed_bytes > block_size:
raise OverflowError('Needed %i bytes for number, but block size '
'is %i' % (needed_bytes, block_size))
# Convert the number to bytes.
while number > 0:
raw_bytes.insert(0, byte(number & 0xFF))
number >>= 8
# Pad with zeroes to fill the block
if block_size and block_size > 0:
padding = (block_size - needed_bytes) * ZERO_BYTE
else:
padding = EMPTY_BYTE
return padding + EMPTY_BYTE.join(raw_bytes)
def bytes_leading(raw_bytes, needle=ZERO_BYTE):
'''
Finds the number of prefixed byte occurrences in the haystack.
Useful when you want to deal with padding.
:param raw_bytes:
Raw bytes.
:param needle:
The byte to count. Default \000.
:returns:
The number of leading needle bytes.
'''
leading = 0
# Indexing keeps compatibility between Python 2.x and Python 3.x
_byte = needle[0]
for x in raw_bytes:
if x == _byte:
leading += 1
else:
break
return leading
def int2bytes(number, fill_size=None, chunk_size=None, overflow=False):
'''
Convert an unsigned integer to bytes (base-256 representation)::
Does not preserve leading zeros if you don't specify a chunk size or
fill size.
.. NOTE:
You must not specify both fill_size and chunk_size. Only one
of them is allowed.
:param number:
Integer value
:param fill_size:
If the optional fill size is given the length of the resulting
byte string is expected to be the fill size and will be padded
with prefix zero bytes to satisfy that length.
:param chunk_size:
If optional chunk size is given and greater than zero, pad the front of
the byte string with binary zeros so that the length is a multiple of
``chunk_size``.
:param overflow:
``False`` (default). If this is ``True``, no ``OverflowError``
will be raised when the fill_size is shorter than the length
of the generated byte sequence. Instead the byte sequence will
be returned as is.
:returns:
Raw bytes (base-256 representation).
:raises:
``OverflowError`` when fill_size is given and the number takes up more
bytes than fit into the block. This requires the ``overflow``
argument to this function to be set to ``False`` otherwise, no
error will be raised.
'''
if number < 0:
raise ValueError("Number must be an unsigned integer: %d" % number)
if fill_size and chunk_size:
raise ValueError("You can either fill or pad chunks, but not both")
# Ensure these are integers.
number & 1
raw_bytes = b('')
# Pack the integer one machine word at a time into bytes.
num = number
word_bits, _, max_uint, pack_type = get_word_alignment(num)
pack_format = ">%s" % pack_type
while num > 0:
raw_bytes = pack(pack_format, num & max_uint) + raw_bytes
num >>= word_bits
# Obtain the index of the first non-zero byte.
zero_leading = bytes_leading(raw_bytes)
if number == 0:
raw_bytes = ZERO_BYTE
# De-padding.
raw_bytes = raw_bytes[zero_leading:]
length = len(raw_bytes)
if fill_size and fill_size > 0:
if not overflow and length > fill_size:
raise OverflowError(
"Need %d bytes for number, but fill size is %d" %
(length, fill_size)
)
raw_bytes = raw_bytes.rjust(fill_size, ZERO_BYTE)
elif chunk_size and chunk_size > 0:
remainder = length % chunk_size
if remainder:
padding_size = chunk_size - remainder
raw_bytes = raw_bytes.rjust(length + padding_size, ZERO_BYTE)
return raw_bytes
if __name__ == '__main__':
import doctest
doctest.testmod()

79
rsa/util.py
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@ -1,79 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''Utility functions.'''
from __future__ import with_statement
import sys
from optparse import OptionParser
import rsa.key
def private_to_public():
'''Reads a private key and outputs the corresponding public key.'''
# Parse the CLI options
parser = OptionParser(usage='usage: %prog [options]',
description='Reads a private key and outputs the '
'corresponding public key. Both private and public keys use '
'the format described in PKCS#1 v1.5')
parser.add_option('-i', '--input', dest='infilename', type='string',
help='Input filename. Reads from stdin if not specified')
parser.add_option('-o', '--output', dest='outfilename', type='string',
help='Output filename. Writes to stdout of not specified')
parser.add_option('--inform', dest='inform',
help='key format of input - default PEM',
choices=('PEM', 'DER'), default='PEM')
parser.add_option('--outform', dest='outform',
help='key format of output - default PEM',
choices=('PEM', 'DER'), default='PEM')
(cli, cli_args) = parser.parse_args(sys.argv)
# Read the input data
if cli.infilename:
print >>sys.stderr, 'Reading private key from %s in %s format' % \
(cli.infilename, cli.inform)
with open(cli.infilename) as infile:
in_data = infile.read()
else:
print >>sys.stderr, 'Reading private key from stdin in %s format' % \
cli.inform
in_data = sys.stdin.read()
# Take the public fields and create a public key
priv_key = rsa.key.PrivateKey.load_pkcs1(in_data, cli.inform)
pub_key = rsa.key.PublicKey(priv_key.n, priv_key.e)
# Save to the output file
out_data = pub_key.save_pkcs1(cli.outform)
if cli.outfilename:
print >>sys.stderr, 'Writing public key to %s in %s format' % \
(cli.outfilename, cli.outform)
with open(cli.outfilename, 'w') as outfile:
outfile.write(out_data)
else:
print >>sys.stderr, 'Writing public key to stdout in %s format' % \
cli.outform
sys.stdout.write(out_data)

155
rsa/varblock.py
View File

@ -1,155 +0,0 @@
# -*- coding: utf-8 -*-
#
# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
'''VARBLOCK file support
The VARBLOCK file format is as follows, where || denotes byte concatenation:
FILE := VERSION || BLOCK || BLOCK ...
BLOCK := LENGTH || DATA
LENGTH := varint-encoded length of the subsequent data. Varint comes from
Google Protobuf, and encodes an integer into a variable number of bytes.
Each byte uses the 7 lowest bits to encode the value. The highest bit set
to 1 indicates the next byte is also part of the varint. The last byte will
have this bit set to 0.
This file format is called the VARBLOCK format, in line with the varint format
used to denote the block sizes.
'''
from rsa._compat import byte, b
ZERO_BYTE = b('\x00')
VARBLOCK_VERSION = 1
def read_varint(infile):
'''Reads a varint from the file.
When the first byte to be read indicates EOF, (0, 0) is returned. When an
EOF occurs when at least one byte has been read, an EOFError exception is
raised.
@param infile: the file-like object to read from. It should have a read()
method.
@returns (varint, length), the read varint and the number of read bytes.
'''
varint = 0
read_bytes = 0
while True:
char = infile.read(1)
if len(char) == 0:
if read_bytes == 0:
return (0, 0)
raise EOFError('EOF while reading varint, value is %i so far' %
varint)
byte = ord(char)
varint += (byte & 0x7F) << (7 * read_bytes)
read_bytes += 1
if not byte & 0x80:
return (varint, read_bytes)
def write_varint(outfile, value):
'''Writes a varint to a file.
@param outfile: the file-like object to write to. It should have a write()
method.
@returns the number of written bytes.
'''
# there is a big difference between 'write the value 0' (this case) and
# 'there is nothing left to write' (the false-case of the while loop)
if value == 0:
outfile.write(ZERO_BYTE)
return 1
written_bytes = 0
while value > 0:
to_write = value & 0x7f
value = value >> 7
if value > 0:
to_write |= 0x80
outfile.write(byte(to_write))
written_bytes += 1
return written_bytes
def yield_varblocks(infile):
'''Generator, yields each block in the input file.
@param infile: file to read, is expected to have the VARBLOCK format as
described in the module's docstring.
@yields the contents of each block.
'''
# Check the version number
first_char = infile.read(1)
if len(first_char) == 0:
raise EOFError('Unable to read VARBLOCK version number')
version = ord(first_char)
if version != VARBLOCK_VERSION:
raise ValueError('VARBLOCK version %i not supported' % version)
while True:
(block_size, read_bytes) = read_varint(infile)
# EOF at block boundary, that's fine.
if read_bytes == 0 and block_size == 0:
break
block = infile.read(block_size)
read_size = len(block)
if read_size != block_size:
raise EOFError('Block size is %i, but could read only %i bytes' %
(block_size, read_size))
yield block
def yield_fixedblocks(infile, blocksize):
'''Generator, yields each block of ``blocksize`` bytes in the input file.
:param infile: file to read and separate in blocks.
:returns: a generator that yields the contents of each block
'''
while True:
block = infile.read(blocksize)
read_bytes = len(block)
if read_bytes == 0:
break
yield block
if read_bytes < blocksize:
break