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/*
* DSA
* (C) 1999-2008 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/dsa.h>
#include <botan/numthry.h>
#include <botan/keypair.h>
#include <botan/look_pk.h>
namespace Botan {
/*
* DSA_PublicKey Constructor
*/
DSA_PublicKey::DSA_PublicKey(const DL_Group& grp, const BigInt& y1)
{
group = grp;
y = y1;
core = DSA_Core(group, y);
}
/*
* DSA Verification Function
*/
bool DSA_PublicKey::verify(const byte msg[], u32bit msg_len,
const byte sig[], u32bit sig_len) const
{
return core.verify(msg, msg_len, sig, sig_len);
}
/*
* Return the maximum input size in bits
*/
u32bit DSA_PublicKey::max_input_bits() const
{
return group_q().bits();
}
/*
* Return the size of each portion of the sig
*/
u32bit DSA_PublicKey::message_part_size() const
{
return group_q().bytes();
}
/*
* Create a DSA private key
*/
DSA_PrivateKey::DSA_PrivateKey(RandomNumberGenerator& rng,
const DL_Group& grp,
const BigInt& x_arg)
{
group = grp;
x = x_arg;
if(x == 0)
x = BigInt::random_integer(rng, 2, group_q() - 1);
y = power_mod(group_g(), x, group_p());
core = DSA_Core(group, y, x);
if(x_arg == 0)
gen_check(rng);
else
load_check(rng);
}
DSA_PrivateKey::DSA_PrivateKey(const AlgorithmIdentifier& alg_id,
const MemoryRegion<byte>& key_bits,
RandomNumberGenerator& rng) :
DL_Scheme_PrivateKey(alg_id, key_bits, DL_Group::ANSI_X9_57)
{
y = power_mod(group_g(), x, group_p());
core = DSA_Core(group, y, x);
load_check(rng);
}
/*
* DSA Signature Operation
*/
SecureVector<byte> DSA_PrivateKey::sign(const byte in[], u32bit length,
RandomNumberGenerator& rng) const
{
const BigInt& q = group_q();
rng.add_entropy(in, length);
BigInt k;
do
k.randomize(rng, q.bits());
while(k >= q);
return core.sign(in, length, k);
}
/*
* Check Private DSA Parameters
*/
bool DSA_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const
{
if(!DL_Scheme_PrivateKey::check_key(rng, strong) || x >= group_q())
return false;
if(!strong)
return true;
try
{
KeyPair::check_key(rng,
get_pk_signer(*this, "EMSA1(SHA-1)"),
get_pk_verifier(*this, "EMSA1(SHA-1)")
);
}
catch(Self_Test_Failure)
{
return false;
}
return true;
}
}
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