Reference client for Bitmessage: a P2P encrypted decentralised communication protocol:
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import hashlib
from struct import *
from pyelliptic import arithmetic
#There is another copy of this function in Bitmessagemain.py
def convertIntToString(n):
a = __builtins__.hex(n)
if a[-1:] == 'L':
a = a[:-1]
if (len(a) % 2) == 0:
return a[2:].decode('hex')
else:
return ('0'+a[2:]).decode('hex')
ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
def encodeBase58(num, alphabet=ALPHABET):
"""Encode a number in Base X
`num`: The number to encode
`alphabet`: The alphabet to use for encoding
"""
if (num == 0):
return alphabet[0]
arr = []
base = len(alphabet)
while num:
rem = num % base
#print 'num is:', num
num = num // base
arr.append(alphabet[rem])
arr.reverse()
return ''.join(arr)
def decodeBase58(string, alphabet=ALPHABET):
"""Decode a Base X encoded string into the number
Arguments:
- `string`: The encoded string
- `alphabet`: The alphabet to use for encoding
"""
base = len(alphabet)
strlen = len(string)
num = 0
try:
power = strlen - 1
for char in string:
num += alphabet.index(char) * (base ** power)
power -= 1
except:
#character not found (like a space character or a 0)
return 0
return num
def encodeVarint(integer):
if integer < 0:
print 'varint cannot be < 0'
raise SystemExit
if integer < 253:
return pack('>B',integer)
if integer >= 253 and integer < 65536:
return pack('>B',253) + pack('>H',integer)
if integer >= 65536 and integer < 4294967296:
return pack('>B',254) + pack('>I',integer)
if integer >= 4294967296 and integer < 18446744073709551616:
return pack('>B',255) + pack('>Q',integer)
if integer >= 18446744073709551616:
print 'varint cannot be >= 18446744073709551616'
raise SystemExit
def decodeVarint(data):
if len(data) == 0:
return (0,0)
firstByte, = unpack('>B',data[0:1])
if firstByte < 253:
return (firstByte,1) #the 1 is the length of the varint
if firstByte == 253:
a, = unpack('>H',data[1:3])
return (a,3)
if firstByte == 254:
a, = unpack('>I',data[1:5])
return (a,5)
if firstByte == 255:
a, = unpack('>Q',data[1:9])
return (a,9)
def calculateInventoryHash(data):
sha = hashlib.new('sha512')
sha2 = hashlib.new('sha512')
sha.update(data)
sha2.update(sha.digest())
return sha2.digest()[0:32]
def encodeAddress(version,stream,ripe):
if version >= 2 and version < 4:
if len(ripe) != 20:
raise Exception("Programming error in encodeAddress: The length of a given ripe hash was not 20.")
if ripe[:2] == '\x00\x00':
ripe = ripe[2:]
elif ripe[:1] == '\x00':
ripe = ripe[1:]
elif version == 4:
if len(ripe) != 20:
raise Exception("Programming error in encodeAddress: The length of a given ripe hash was not 20.")
ripe = ripe.lstrip('\x00')
a = encodeVarint(version) + encodeVarint(stream) + ripe
sha = hashlib.new('sha512')
sha.update(a)
currentHash = sha.digest()
#print 'sha after first hashing: ', sha.hexdigest()
sha = hashlib.new('sha512')
sha.update(currentHash)
#print 'sha after second hashing: ', sha.hexdigest()
checksum = sha.digest()[0:4]
#print 'len(a) = ', len(a)
#print 'checksum = ', checksum.encode('hex')
#print 'len(checksum) = ', len(checksum)
asInt = int(a.encode('hex') + checksum.encode('hex'),16)
#asInt = int(checksum.encode('hex') + a.encode('hex'),16)
# print asInt
return 'BM-'+ encodeBase58(asInt)
def decodeAddress(address):
#returns (status, address version number, stream number, data (almost certainly a ripe hash))
address = str(address).strip()
if address[:3] == 'BM-':
integer = decodeBase58(address[3:])
else:
integer = decodeBase58(address)
if integer == 0:
status = 'invalidcharacters'
return status,0,0,0
#after converting to hex, the string will be prepended with a 0x and appended with a L
hexdata = hex(integer)[2:-1]
if len(hexdata) % 2 != 0:
hexdata = '0' + hexdata
#print 'hexdata', hexdata
data = hexdata.decode('hex')
checksum = data[-4:]
sha = hashlib.new('sha512')
sha.update(data[:-4])
currentHash = sha.digest()
#print 'sha after first hashing: ', sha.hexdigest()
sha = hashlib.new('sha512')
sha.update(currentHash)
#print 'sha after second hashing: ', sha.hexdigest()
if checksum != sha.digest()[0:4]:
status = 'checksumfailed'
return status,0,0,0
#else:
# print 'checksum PASSED'
addressVersionNumber, bytesUsedByVersionNumber = decodeVarint(data[:9])
#print 'addressVersionNumber', addressVersionNumber
#print 'bytesUsedByVersionNumber', bytesUsedByVersionNumber
if addressVersionNumber > 4:
print 'cannot decode address version numbers this high'
status = 'versiontoohigh'
return status,0,0,0
elif addressVersionNumber == 0:
print 'cannot decode address version numbers of zero.'
status = 'versiontoohigh'
return status,0,0,0
streamNumber, bytesUsedByStreamNumber = decodeVarint(data[bytesUsedByVersionNumber:])
#print streamNumber
status = 'success'
if addressVersionNumber == 1:
return status,addressVersionNumber,streamNumber,data[-24:-4]
elif addressVersionNumber == 2 or addressVersionNumber == 3:
if len(data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]) == 19:
return status,addressVersionNumber,streamNumber,'\x00'+data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]
elif len(data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]) == 20:
return status,addressVersionNumber,streamNumber,data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]
elif len(data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]) == 18:
return status,addressVersionNumber,streamNumber,'\x00\x00'+data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]
elif len(data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]) < 18:
return 'ripetooshort',0,0,0
elif len(data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]) > 20:
return 'ripetoolong',0,0,0
else:
return 'otherproblem',0,0,0
elif addressVersionNumber == 4:
if len(data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]) > 20:
return 'ripetoolong',0,0,0
elif len(data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]) < 4:
return 'ripetooshort',0,0,0
else:
x00string = '\x00' * (20 - len(data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]))
return status,addressVersionNumber,streamNumber,x00string+data[bytesUsedByVersionNumber+bytesUsedByStreamNumber:-4]
def addBMIfNotPresent(address):
address = str(address).strip()
if address[:3] != 'BM-':
return 'BM-'+address
else:
return address
if __name__ == "__main__":
print 'Let us make an address from scratch. Suppose we generate two random 32 byte values and call the first one the signing key and the second one the encryption key:'
privateSigningKey = '93d0b61371a54b53df143b954035d612f8efa8a3ed1cf842c2186bfd8f876665'
privateEncryptionKey = '4b0b73a54e19b059dc274ab69df095fe699f43b17397bca26fdf40f4d7400a3a'
print 'privateSigningKey =', privateSigningKey
print 'privateEncryptionKey =', privateEncryptionKey
print 'Now let us convert them to public keys by doing an elliptic curve point multiplication.'
publicSigningKey = arithmetic.privtopub(privateSigningKey)
publicEncryptionKey = arithmetic.privtopub(privateEncryptionKey)
print 'publicSigningKey =', publicSigningKey
print 'publicEncryptionKey =', publicEncryptionKey
print 'Notice that they both begin with the \\x04 which specifies the encoding type. This prefix is not send over the wire. You must strip if off before you send your public key across the wire, and you must add it back when you receive a public key.'
publicSigningKeyBinary = arithmetic.changebase(publicSigningKey,16,256,minlen=64)
publicEncryptionKeyBinary = arithmetic.changebase(publicEncryptionKey,16,256,minlen=64)
ripe = hashlib.new('ripemd160')
sha = hashlib.new('sha512')
sha.update(publicSigningKeyBinary+publicEncryptionKeyBinary)
ripe.update(sha.digest())
addressVersionNumber = 2
streamNumber = 1
print 'Ripe digest that we will encode in the address:', ripe.digest().encode('hex')
returnedAddress = encodeAddress(addressVersionNumber,streamNumber,ripe.digest())
print 'Encoded address:', returnedAddress
status,addressVersionNumber,streamNumber,data = decodeAddress(returnedAddress)
print '\nAfter decoding address:'
print 'Status:', status
print 'addressVersionNumber', addressVersionNumber
print 'streamNumber', streamNumber
print 'length of data(the ripe hash):', len(data)
print 'ripe data:', data.encode('hex')