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mikhail4021 2014-02-23 21:54:36 +04:00
parent 885dc6603f
commit 2deb4118bc
31 changed files with 783 additions and 212 deletions
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58
ElGamal.h
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@ -12,25 +12,47 @@ namespace i2p
{
namespace crypto
{
inline void ElGamalEncrypt (const uint8_t * key, const uint8_t * data, int len,
uint8_t * encrypted, bool zeroPadding = false) // 514 with padding and 512 without
{
CryptoPP::AutoSeededRandomPool rnd;
CryptoPP::Integer y(key, 256), k(rnd, CryptoPP::Integer::One(), elgp-1);
if (zeroPadding)
{
encrypted[0] = 0;
encrypted[257] = 0;
}
a_exp_b_mod_c (elgg, k, elgp).Encode (zeroPadding ? encrypted + 1 : encrypted, 256);
uint8_t m[255];
m[0] = 0xFF;
memcpy (m+33, data, len);
CryptoPP::SHA256().CalculateDigest(m+1, m+33, 222);
a_times_b_mod_c (a_exp_b_mod_c (y, k, elgp),
CryptoPP::Integer (m, 255), elgp).Encode (zeroPadding ? encrypted + 258 : encrypted + 256, 256);
}
class ElGamalEncryption
{
public:
ElGamalEncryption (const uint8_t * key):
y (key, 256), k (rnd, CryptoPP::Integer::One(), elgp-1),
a (a_exp_b_mod_c (elgg, k, elgp)), b1 (a_exp_b_mod_c (y, k, elgp))
{
}
void Encrypt (const uint8_t * data, int len, uint8_t * encrypted, bool zeroPadding = false)
{
// calculate b = b1*m mod p
uint8_t m[255];
m[0] = 0xFF;
memcpy (m+33, data, len);
CryptoPP::SHA256().CalculateDigest(m+1, m+33, 222);
CryptoPP::Integer b (a_times_b_mod_c (b1, CryptoPP::Integer (m, 255), elgp));
// copy a and b
if (zeroPadding)
{
encrypted[0] = 0;
a.Encode (encrypted + 1, 256);
encrypted[257] = 0;
b.Encode (encrypted + 258, 256);
}
else
{
a.Encode (encrypted, 256);
b.Encode (encrypted + 256, 256);
}
}
private:
CryptoPP::AutoSeededRandomPool rnd;
CryptoPP::Integer y, k, a, b1;
bool m_ZeroPadding;
};
inline bool ElGamalDecrypt (const uint8_t * key, const uint8_t * encrypted,
uint8_t * data, bool zeroPadding = false)