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/*
* Diffie-Hellman
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_DIFFIE_HELLMAN_H__
#define BOTAN_DIFFIE_HELLMAN_H__
#include <botan/dl_algo.h>
#include <botan/pow_mod.h>
#include <botan/pk_ops.h>
namespace Botan {
/**
* This class represents Diffie-Hellman public keys.
*/
class BOTAN_DLL DH_PublicKey : public virtual DL_Scheme_PublicKey
{
public:
std::string algo_name() const { return "DH"; }
MemoryVector<byte> public_value() const;
u32bit max_input_bits() const { return group_p().bits(); }
DL_Group::Format group_format() const { return DL_Group::ANSI_X9_42; }
DH_PublicKey(const AlgorithmIdentifier& alg_id,
const MemoryRegion<byte>& key_bits) :
DL_Scheme_PublicKey(alg_id, key_bits, DL_Group::ANSI_X9_42) {}
/**
* Construct a public key with the specified parameters.
* @param grp the DL group to use in the key
* @param y the public value y
*/
DH_PublicKey(const DL_Group& grp, const BigInt& y);
protected:
DH_PublicKey() {}
};
/**
* This class represents Diffie-Hellman private keys.
*/
class BOTAN_DLL DH_PrivateKey : public DH_PublicKey,
public PK_Key_Agreement_Key,
public virtual DL_Scheme_PrivateKey
{
public:
MemoryVector<byte> public_value() const;
/**
* Load a DH private key
* @param alg_id the algorithm id
* @param key_bits the subject public key
* @rng a random number generator
*/
DH_PrivateKey(const AlgorithmIdentifier& alg_id,
const MemoryRegion<byte>& key_bits,
RandomNumberGenerator& rng);
/**
* Construct a private key with predetermined value.
* @param rng random number generator to use
* @param grp the group to be used in the key
* @param x the key's secret value (or if zero, generate a new key)
*/
DH_PrivateKey(RandomNumberGenerator& rng, const DL_Group& grp,
const BigInt& x = 0);
};
/**
* DH operation
*/
class BOTAN_DLL DH_KA_Operation : public PK_Ops::KA_Operation
{
public:
DH_KA_Operation(const DH_PrivateKey& key) :
powermod_x_p(key.get_x(), key.get_domain().get_p()),
p_bytes(key.get_domain().get_p().bytes())
{}
SecureVector<byte> agree(const byte w[], u32bit w_len) const
{
return BigInt::encode_1363(
powermod_x_p(BigInt::decode(w, w_len)),
p_bytes);
}
private:
Fixed_Exponent_Power_Mod powermod_x_p;
u32bit p_bytes;
};
}
#endif
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