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PyBitmessage/src/highlevelcrypto.py

94 lines
3.9 KiB

from binascii import hexlify
import pyelliptic
from pyelliptic import arithmetic as a, OpenSSL
def makeCryptor(privkey):
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):
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):
pubkey_bin = hexToPubkey(pubkey)
return pyelliptic.ECC(curve='secp256k1',pubkey=pubkey_bin)
# Converts hex private key into hex public key
def privToPub(privkey):
private_key = a.changebase(privkey, 16, 256, minlen=32)
public_key = pointMult(private_key)
return hexlify(public_key)
# Encrypts message with hex public key
def encrypt(msg,hexPubkey):
return pyelliptic.ECC(curve='secp256k1').encrypt(msg,hexToPubkey(hexPubkey))
# Decrypts message with hex private key
def decrypt(msg,hexPrivkey):
return makeCryptor(hexPrivkey).decrypt(msg)
# Decrypts message with an existing pyelliptic.ECC.ECC object
def decryptFast(msg,cryptor):
return cryptor.decrypt(msg)
# Signs with hex private key
def sign(msg,hexPrivkey):
# pyelliptic is upgrading from SHA1 to SHA256 for signing. We must
# upgrade PyBitmessage gracefully.
# https://github.com/yann2192/pyelliptic/pull/33
# More discussion: https://github.com/yann2192/pyelliptic/issues/32
return makeCryptor(hexPrivkey).sign(msg, digest_alg=OpenSSL.digest_ecdsa_sha1) # SHA1
#return makeCryptor(hexPrivkey).sign(msg, digest_alg=OpenSSL.EVP_sha256) # SHA256. We should switch to this eventually.
# Verifies with hex public key
def verify(msg,sig,hexPubkey):
# 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:
sigVerifyPassed = makePubCryptor(hexPubkey).verify(sig,msg,digest_alg=OpenSSL.digest_ecdsa_sha1) # old SHA1 algorithm.
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
# Does an EC point multiplication; turns a private key into a public key.
def pointMult(secret):
while True:
try:
"""
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
"""
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 as e:
import traceback
import time
traceback.print_exc()
time.sleep(0.2)