142 lines
4.6 KiB
Python
142 lines
4.6 KiB
Python
"""
|
|
High level cryptographic functions based on `.pyelliptic` OpenSSL bindings.
|
|
|
|
.. note::
|
|
Upstream pyelliptic was upgraded from SHA1 to SHA256 for signing.
|
|
We must upgrade PyBitmessage gracefully.
|
|
`More discussion. <https://github.com/yann2192/pyelliptic/issues/32>`_
|
|
"""
|
|
|
|
from binascii import hexlify
|
|
|
|
import pyelliptic
|
|
from bmconfigparser import BMConfigParser
|
|
from pyelliptic import OpenSSL
|
|
from pyelliptic import arithmetic as a
|
|
|
|
|
|
def makeCryptor(privkey):
|
|
"""Return a private `.pyelliptic.ECC` instance"""
|
|
private_key = a.changebase(privkey, 16, 256, minlen=32)
|
|
public_key = pointMult(private_key)
|
|
privkey_bin = '\x02\xca\x00\x20' + private_key
|
|
pubkey_bin = '\x02\xca\x00\x20' + public_key[1:-32] + '\x00\x20' + public_key[-32:]
|
|
cryptor = pyelliptic.ECC(
|
|
curve='secp256k1', privkey=privkey_bin, pubkey=pubkey_bin)
|
|
return cryptor
|
|
|
|
|
|
def hexToPubkey(pubkey):
|
|
"""Convert a pubkey from hex to binary"""
|
|
pubkey_raw = a.changebase(pubkey[2:], 16, 256, minlen=64)
|
|
pubkey_bin = '\x02\xca\x00 ' + pubkey_raw[:32] + '\x00 ' + pubkey_raw[32:]
|
|
return pubkey_bin
|
|
|
|
|
|
def makePubCryptor(pubkey):
|
|
"""Return a public `.pyelliptic.ECC` instance"""
|
|
pubkey_bin = hexToPubkey(pubkey)
|
|
return pyelliptic.ECC(curve='secp256k1', pubkey=pubkey_bin)
|
|
|
|
|
|
def privToPub(privkey):
|
|
"""Converts hex private key into hex public key"""
|
|
private_key = a.changebase(privkey, 16, 256, minlen=32)
|
|
public_key = pointMult(private_key)
|
|
return hexlify(public_key)
|
|
|
|
|
|
def encrypt(msg, hexPubkey):
|
|
"""Encrypts message with hex public key"""
|
|
return pyelliptic.ECC(curve='secp256k1').encrypt(
|
|
msg, hexToPubkey(hexPubkey))
|
|
|
|
|
|
def decrypt(msg, hexPrivkey):
|
|
"""Decrypts message with hex private key"""
|
|
return makeCryptor(hexPrivkey).decrypt(msg)
|
|
|
|
|
|
def decryptFast(msg, cryptor):
|
|
"""Decrypts message with an existing `.pyelliptic.ECC` object"""
|
|
return cryptor.decrypt(msg)
|
|
|
|
|
|
def sign(msg, hexPrivkey):
|
|
"""
|
|
Signs with hex private key using SHA1 or SHA256 depending on
|
|
"digestalg" setting
|
|
"""
|
|
digestAlg = BMConfigParser().safeGet(
|
|
'bitmessagesettings', 'digestalg', 'sha1')
|
|
if digestAlg == "sha1":
|
|
# SHA1, this will eventually be deprecated
|
|
return makeCryptor(hexPrivkey).sign(
|
|
msg, digest_alg=OpenSSL.digest_ecdsa_sha1)
|
|
elif digestAlg == "sha256":
|
|
# SHA256. Eventually this will become the default
|
|
return makeCryptor(hexPrivkey).sign(msg, digest_alg=OpenSSL.EVP_sha256)
|
|
else:
|
|
raise ValueError("Unknown digest algorithm %s" % digestAlg)
|
|
|
|
|
|
def verify(msg, sig, hexPubkey):
|
|
"""Verifies with hex public key using SHA1 or SHA256"""
|
|
# As mentioned above, we must upgrade gracefully to use SHA256. So
|
|
# let us check the signature using both SHA1 and SHA256 and if one
|
|
# of them passes then we will be satisfied. Eventually this can
|
|
# be simplified and we'll only check with SHA256.
|
|
try:
|
|
# old SHA1 algorithm.
|
|
sigVerifyPassed = makePubCryptor(hexPubkey).verify(
|
|
sig, msg, digest_alg=OpenSSL.digest_ecdsa_sha1)
|
|
except:
|
|
sigVerifyPassed = False
|
|
if sigVerifyPassed:
|
|
# The signature check passed using SHA1
|
|
return True
|
|
# The signature check using SHA1 failed. Let us try it with SHA256.
|
|
try:
|
|
return makePubCryptor(hexPubkey).verify(
|
|
sig, msg, digest_alg=OpenSSL.EVP_sha256)
|
|
except:
|
|
return False
|
|
|
|
|
|
def pointMult(secret):
|
|
"""
|
|
Does an EC point multiplication; turns a private key into a public key.
|
|
|
|
Evidently, this type of error can occur very rarely:
|
|
|
|
>>> File "highlevelcrypto.py", line 54, in pointMult
|
|
>>> group = OpenSSL.EC_KEY_get0_group(k)
|
|
>>> WindowsError: exception: access violation reading 0x0000000000000008
|
|
"""
|
|
while True:
|
|
try:
|
|
k = OpenSSL.EC_KEY_new_by_curve_name(
|
|
OpenSSL.get_curve('secp256k1'))
|
|
priv_key = OpenSSL.BN_bin2bn(secret, 32, None)
|
|
group = OpenSSL.EC_KEY_get0_group(k)
|
|
pub_key = OpenSSL.EC_POINT_new(group)
|
|
|
|
OpenSSL.EC_POINT_mul(group, pub_key, priv_key, None, None, None)
|
|
OpenSSL.EC_KEY_set_private_key(k, priv_key)
|
|
OpenSSL.EC_KEY_set_public_key(k, pub_key)
|
|
|
|
size = OpenSSL.i2o_ECPublicKey(k, None)
|
|
mb = OpenSSL.create_string_buffer(size)
|
|
OpenSSL.i2o_ECPublicKey(k, OpenSSL.byref(OpenSSL.pointer(mb)))
|
|
|
|
OpenSSL.EC_POINT_free(pub_key)
|
|
OpenSSL.BN_free(priv_key)
|
|
OpenSSL.EC_KEY_free(k)
|
|
return mb.raw
|
|
|
|
except Exception:
|
|
import traceback
|
|
import time
|
|
traceback.print_exc()
|
|
time.sleep(0.2)
|