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Diffstat (limited to 'botan/src/pubkey/elgamal/elgamal.cpp')
-rw-r--r-- | botan/src/pubkey/elgamal/elgamal.cpp | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/botan/src/pubkey/elgamal/elgamal.cpp b/botan/src/pubkey/elgamal/elgamal.cpp new file mode 100644 index 0000000..1f79df5 --- /dev/null +++ b/botan/src/pubkey/elgamal/elgamal.cpp @@ -0,0 +1,124 @@ +/* +* ElGamal +* (C) 1999-2007 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#include <botan/elgamal.h> +#include <botan/numthry.h> +#include <botan/keypair.h> +#include <botan/look_pk.h> +#include <botan/util.h> + +namespace Botan { + +/* +* ElGamal_PublicKey Constructor +*/ +ElGamal_PublicKey::ElGamal_PublicKey(const DL_Group& grp, const BigInt& y1) + { + group = grp; + y = y1; + X509_load_hook(); + } + +/* +* Algorithm Specific X.509 Initialization Code +*/ +void ElGamal_PublicKey::X509_load_hook() + { + core = ELG_Core(group, y); + } + +/* +* ElGamal Encryption Function +*/ +SecureVector<byte> +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(RandomNumberGenerator& rng, + const DL_Group& grp, + const BigInt& x_arg) + { + group = grp; + x = x_arg; + + if(x == 0) + { + x.randomize(rng, 2 * dl_work_factor(group_p().bits())); + PKCS8_load_hook(rng, true); + } + else + PKCS8_load_hook(rng, false); + } + +/* +* 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<byte> 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; + } + +} |