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/*************************************************
* DSA Source File *
* (C) 1999-2007 The Botan Project *
*************************************************/
#include <botan/dsa.h>
#include <botan/numthry.h>
#include <botan/keypair.h>
namespace Botan {
/*************************************************
* DSA_PublicKey Constructor *
*************************************************/
DSA_PublicKey::DSA_PublicKey(const DL_Group& grp, const BigInt& y1)
{
group = grp;
y = y1;
X509_load_hook();
}
/*************************************************
* Algorithm Specific X.509 Initialization Code *
*************************************************/
void DSA_PublicKey::X509_load_hook()
{
core = DSA_Core(group, y);
load_check();
}
/*************************************************
* 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(const DL_Group& grp)
{
group = grp;
x = random_integer(2, group_q() - 1);
PKCS8_load_hook(true);
}
/*************************************************
* DSA_PrivateKey Constructor *
*************************************************/
DSA_PrivateKey::DSA_PrivateKey(const DL_Group& grp, const BigInt& x1,
const BigInt& y1)
{
group = grp;
y = y1;
x = x1;
PKCS8_load_hook();
}
/*************************************************
* Algorithm Specific PKCS #8 Initialization Code *
*************************************************/
void DSA_PrivateKey::PKCS8_load_hook(bool generated)
{
if(y == 0)
y = power_mod(group_g(), x, group_p());
core = DSA_Core(group, y, x);
if(generated)
gen_check();
else
load_check();
}
/*************************************************
* DSA Signature Operation *
*************************************************/
SecureVector<byte> DSA_PrivateKey::sign(const byte in[], u32bit length) const
{
const BigInt& q = group_q();
BigInt k;
do
k.randomize(q.bits());
while(k >= q);
return core.sign(in, length, k);
}
/*************************************************
* Check Private DSA Parameters *
*************************************************/
bool DSA_PrivateKey::check_key(bool strong) const
{
if(!DL_Scheme_PrivateKey::check_key(strong) || x >= group_q())
return false;
if(!strong)
return true;
try {
KeyPair::check_key(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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