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/*
* Nyberg-Rueppel
* (C) 1999-2010 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/nr.h>
#include <botan/numthry.h>
#include <botan/keypair.h>
#include <botan/look_pk.h>
namespace Botan {
NR_PublicKey::NR_PublicKey(const AlgorithmIdentifier& alg_id,
const MemoryRegion<byte>& key_bits) :
DL_Scheme_PublicKey(alg_id, key_bits, DL_Group::ANSI_X9_57)
{
core = NR_Core(group, y);
}
/*
* NR_PublicKey Constructor
*/
NR_PublicKey::NR_PublicKey(const DL_Group& grp, const BigInt& y1)
{
group = grp;
y = y1;
core = NR_Core(group, y);
}
/*
* Nyberg-Rueppel Verification Function
*/
SecureVector<byte> NR_PublicKey::verify(const byte sig[], u32bit sig_len) const
{
return core.verify(sig, sig_len);
}
/*
* Create a NR private key
*/
NR_PrivateKey::NR_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 = NR_Core(group, y, x);
if(x_arg == 0)
gen_check(rng);
else
load_check(rng);
}
NR_PrivateKey::NR_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 = NR_Core(group, y, x);
load_check(rng);
}
/*
* Check Private Nyberg-Rueppel Parameters
*/
bool NR_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;
}
NR_Signature_Operation::NR_Signature_Operation(const NR_PrivateKey& nr) :
q(nr.group_q()),
x(nr.get_x()),
powermod_g_p(nr.group_g(), nr.group_p()),
mod_q(nr.group_q())
{
}
SecureVector<byte> NR_Signature_Operation::sign(const byte msg[],
u32bit msg_len,
RandomNumberGenerator& rng)
{
rng.add_entropy(msg, msg_len);
BigInt k;
do
k.randomize(rng, q.bits());
while(k >= q);
BigInt f(msg, msg_len);
if(f >= q)
throw Invalid_Argument("NR_Signature_Operation: Input is out of range");
BigInt c = mod_q.reduce(powermod_g_p(k) + f);
if(c.is_zero())
throw Internal_Error("NR_Signature_Operation: c was zero");
BigInt d = mod_q.reduce(k - x * c);
SecureVector<byte> output(2*q.bytes());
c.binary_encode(output + (output.size() / 2 - c.bytes()));
d.binary_encode(output + (output.size() - d.bytes()));
return output;
}
}
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