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/*
* TLS v1.0 and v1.2 PRFs
* (C) 2004-2010 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/prf_tls.h>
#include <botan/internal/xor_buf.h>
#include <botan/hmac.h>
#include <botan/md5.h>
#include <botan/sha160.h>
namespace Botan {
namespace {
/*
* TLS PRF P_hash function
*/
void P_hash(byte output[], u32bit output_len,
MessageAuthenticationCode* mac,
const byte secret[], u32bit secret_len,
const byte seed[], u32bit seed_len)
{
mac->set_key(secret, secret_len);
SecureVector<byte> A(seed, seed_len);
while(output_len)
{
const u32bit this_block_len =
std::min(mac->OUTPUT_LENGTH, output_len);
A = mac->process(A);
mac->update(A);
mac->update(seed, seed_len);
SecureVector<byte> block = mac->final();
xor_buf(output, &block[0], this_block_len);
output_len -= this_block_len;
output += this_block_len;
}
}
}
/*
* TLS PRF Constructor and Destructor
*/
TLS_PRF::TLS_PRF()
{
hmac_md5 = new HMAC(new MD5);
hmac_sha1 = new HMAC(new SHA_160);
}
TLS_PRF::~TLS_PRF()
{
delete hmac_md5;
delete hmac_sha1;
}
/*
* TLS PRF
*/
SecureVector<byte> TLS_PRF::derive(u32bit key_len,
const byte secret[], u32bit secret_len,
const byte seed[], u32bit seed_len) const
{
SecureVector<byte> output(key_len);
u32bit S1_len = (secret_len + 1) / 2,
S2_len = (secret_len + 1) / 2;
const byte* S1 = secret;
const byte* S2 = secret + (secret_len - S2_len);
P_hash(output, key_len, hmac_md5, S1, S1_len, seed, seed_len);
P_hash(output, key_len, hmac_sha1, S2, S2_len, seed, seed_len);
return output;
}
/*
* TLS v1.2 PRF Constructor and Destructor
*/
TLS_12_PRF::TLS_12_PRF(HashFunction* hash)
{
hmac = new HMAC(hash);
}
TLS_12_PRF::~TLS_12_PRF()
{
delete hmac;
}
SecureVector<byte> TLS_12_PRF::derive(u32bit key_len,
const byte secret[], u32bit secret_len,
const byte seed[], u32bit seed_len) const
{
SecureVector<byte> output(key_len);
P_hash(output, key_len, hmac, secret, secret_len, seed, seed_len);
return output;
}
}
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