/************************************************* * ElGamal Source File * * (C) 1999-2007 Jack Lloyd * *************************************************/ #include #include #include #include #include namespace Botan { /************************************************* * ElGamal_PublicKey Constructor * *************************************************/ ElGamal_PublicKey::ElGamal_PublicKey(const DL_Group& grp, const BigInt& y1) { group = grp; y = y1; X509_load_hook(global_state().prng_reference()); } /************************************************* * Algorithm Specific X.509 Initialization Code * *************************************************/ void ElGamal_PublicKey::X509_load_hook(RandomNumberGenerator& rng) { core = ELG_Core(rng, group, y); load_check(rng); } /************************************************* * ElGamal Encryption Function * *************************************************/ SecureVector ElGamal_PublicKey::encrypt(const byte in[], u32bit length, RandomNumberGenerator& rng) const { BigInt k(rng, 2 * dl_work_factor(group_p().bits())); return core.encrypt(in, length, k); } /************************************************* * Return the maximum input size in bits * *************************************************/ u32bit ElGamal_PublicKey::max_input_bits() const { return (group_p().bits() - 1); } /************************************************* * ElGamal_PrivateKey Constructor * *************************************************/ ElGamal_PrivateKey::ElGamal_PrivateKey(const DL_Group& grp, RandomNumberGenerator& rng) { group = grp; x.randomize(rng, 2 * dl_work_factor(group_p().bits())); PKCS8_load_hook(rng, true); } /************************************************* * ElGamal_PrivateKey Constructor * *************************************************/ ElGamal_PrivateKey::ElGamal_PrivateKey(const DL_Group& grp, const BigInt& x1, const BigInt& y1) { group = grp; y = y1; x = x1; PKCS8_load_hook(global_state().prng_reference()); } /************************************************* * Algorithm Specific PKCS #8 Initialization Code * *************************************************/ void ElGamal_PrivateKey::PKCS8_load_hook(RandomNumberGenerator& rng, bool generated) { if(y == 0) y = power_mod(group_g(), x, group_p()); core = ELG_Core(rng, group, y, x); if(generated) gen_check(rng); else load_check(rng); } /************************************************* * ElGamal Decryption Function * *************************************************/ SecureVector ElGamal_PrivateKey::decrypt(const byte in[], u32bit length) const { return core.decrypt(in, length); } /************************************************* * Check Private ElGamal Parameters * *************************************************/ bool ElGamal_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const { if(!DL_Scheme_PrivateKey::check_key(rng, strong)) return false; if(!strong) return true; try { KeyPair::check_key(rng, get_pk_encryptor(*this, "EME1(SHA-1)"), get_pk_decryptor(*this, "EME1(SHA-1)") ); } catch(Self_Test_Failure) { return false; } return true; } }