diff options
| -rw-r--r-- | lib/Crypto/PublicKey/ElGamal.py | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/lib/Crypto/PublicKey/ElGamal.py b/lib/Crypto/PublicKey/ElGamal.py index 99af71c..0ab07fc 100644 --- a/lib/Crypto/PublicKey/ElGamal.py +++ b/lib/Crypto/PublicKey/ElGamal.py @@ -111,6 +111,7 @@ __all__ = ['generate', 'construct', 'error', 'ElGamalobj'] from Crypto.PublicKey.pubkey import * from Crypto.Util import number +from Crypto import Random class error (Exception): pass @@ -242,6 +243,11 @@ class ElGamalobj(pubkey): #: - **x**, the private key. keydata=['p', 'g', 'y', 'x'] + def __init__(self, randfunc=None): + if randfunc is None: + randfunc = Random.new().read + self._randfunc = randfunc + def encrypt(self, plaintext, K): """Encrypt a piece of data with ElGamal. @@ -331,8 +337,11 @@ class ElGamalobj(pubkey): def _decrypt(self, M): if (not hasattr(self, 'x')): raise TypeError('Private key not available in this object') - ax=pow(M[0], self.x, self.p) - plaintext=(M[1] * inverse(ax, self.p ) ) % self.p + r = number.getRandomRange(2, self.p-1, self._randfunc) + a_blind = (M[0] * pow(self.g, r, self.p)) % self.p + ax=pow(a_blind, self.x, self.p) + plaintext_blind = (M[1] * inverse(ax, self.p ) ) % self.p + plaintext = (plaintext_blind * pow(self.y, r, self.p)) % self.p return plaintext def _sign(self, M, K): |