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/*
* RSA
* (C) 1999-2008 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/rsa.h>
#include <botan/parsing.h>
#include <botan/numthry.h>
#include <botan/keypair.h>
#include <botan/look_pk.h>
namespace Botan {
/*
* RSA Public Operation
*/
BigInt RSA_PublicKey::public_op(const BigInt& i) const
{
if(i >= n)
throw Invalid_Argument(algo_name() + "::public_op: input is too large");
return core.public_op(i);
}
/*
* RSA Encryption Function
*/
SecureVector<byte> RSA_PublicKey::encrypt(const byte in[], u32bit len,
RandomNumberGenerator&) const
{
BigInt i(in, len);
return BigInt::encode_1363(public_op(i), n.bytes());
}
/*
* Create a RSA private key
*/
RSA_PrivateKey::RSA_PrivateKey(RandomNumberGenerator& rng,
u32bit bits, u32bit exp)
{
if(bits < 512)
throw Invalid_Argument(algo_name() + ": Can't make a key that is only " +
to_string(bits) + " bits long");
if(exp < 3 || exp % 2 == 0)
throw Invalid_Argument(algo_name() + ": Invalid encryption exponent");
e = exp;
p = random_prime(rng, (bits + 1) / 2, e);
q = random_prime(rng, bits - p.bits(), e);
n = p * q;
if(n.bits() != bits)
throw Self_Test_Failure(algo_name() + " private key generation failed");
d = inverse_mod(e, lcm(p - 1, q - 1));
d1 = d % (p - 1);
d2 = d % (q - 1);
c = inverse_mod(q, p);
core = IF_Core(rng, e, n, d, p, q, d1, d2, c);
gen_check(rng);
}
/*
* RSA Private Operation
*/
BigInt RSA_PrivateKey::private_op(const byte in[], u32bit length) const
{
BigInt i(in, length);
if(i >= n)
throw Invalid_Argument(algo_name() + "::private_op: input is too large");
BigInt r = core.private_op(i);
if(i != public_op(r))
throw Self_Test_Failure(algo_name() + " private operation check failed");
return r;
}
/*
* RSA Decryption Operation
*/
SecureVector<byte> RSA_PrivateKey::decrypt(const byte in[], u32bit len) const
{
return BigInt::encode(private_op(in, len));
}
/*
* Check Private RSA Parameters
*/
bool RSA_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const
{
if(!IF_Scheme_PrivateKey::check_key(rng, strong))
return false;
if(!strong)
return true;
if((e * d) % lcm(p - 1, q - 1) != 1)
return false;
try
{
KeyPair::check_key(rng,
get_pk_encryptor(*this, "EME1(SHA-1)"),
get_pk_decryptor(*this, "EME1(SHA-1)")
);
KeyPair::check_key(rng,
get_pk_signer(*this, "EMSA4(SHA-1)"),
get_pk_verifier(*this, "EMSA4(SHA-1)")
);
}
catch(Self_Test_Failure)
{
return false;
}
return true;
}
RSA_Signature_Operation::RSA_Signature_Operation(const RSA_PrivateKey& rsa) :
q(rsa.get_q()),
c(rsa.get_c()),
powermod_d1_p(rsa.get_d1(), rsa.get_p()),
powermod_d2_q(rsa.get_d2(), rsa.get_q()),
mod_p(rsa.get_p()),
n_bits(rsa.get_n().bits())
{
}
SecureVector<byte> RSA_Signature_Operation::sign(const byte msg[],
u32bit msg_len,
RandomNumberGenerator&)
{
const u32bit n_bytes = (n_bits + 7) / 8;
BigInt i(msg, msg_len);
BigInt j1 = powermod_d1_p(i);
BigInt j2 = powermod_d2_q(i);
j1 = mod_p.reduce(sub_mul(j1, j2, c));
return BigInt::encode_1363(mul_add(j1, q, j2), n_bytes);
}
}
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