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/*
* Copyright (C) 2010 Martin Willi
* Copyright (C) 2010 revosec AG
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "tls_prf.h"
typedef struct private_tls_prf12_t private_tls_prf12_t;
/**
* Private data of an tls_prf_t object.
*/
struct private_tls_prf12_t {
/**
* Public tls_prf_t interface.
*/
tls_prf_t public;
/**
* Underlying primitive PRF
*/
prf_t *prf;
};
METHOD(tls_prf_t, set_key12, bool,
private_tls_prf12_t *this, chunk_t key)
{
return this->prf->set_key(this->prf, key);
}
/**
* The P_hash function as in TLS 1.0/1.2
*/
static bool p_hash(prf_t *prf, char *label, chunk_t seed, size_t block_size,
size_t bytes, char *out)
{
char buf[block_size], abuf[block_size];
chunk_t a;
/* seed = label + seed */
seed = chunk_cata("cc", chunk_create(label, strlen(label)), seed);
/* A(0) = seed */
a = seed;
while (TRUE)
{
/* A(i) = HMAC_hash(secret, A(i-1)) */
if (!prf->get_bytes(prf, a, abuf))
{
return FALSE;
}
a = chunk_from_thing(abuf);
/* HMAC_hash(secret, A(i) + seed) */
if (!prf->get_bytes(prf, a, NULL) ||
!prf->get_bytes(prf, seed, buf))
{
return FALSE;
}
if (bytes <= block_size)
{
memcpy(out, buf, bytes);
break;
}
memcpy(out, buf, block_size);
out += block_size;
bytes -= block_size;
}
return TRUE;
}
METHOD(tls_prf_t, get_bytes12, bool,
private_tls_prf12_t *this, char *label, chunk_t seed,
size_t bytes, char *out)
{
return p_hash(this->prf, label, seed, this->prf->get_block_size(this->prf),
bytes, out);
}
METHOD(tls_prf_t, destroy12, void,
private_tls_prf12_t *this)
{
this->prf->destroy(this->prf);
free(this);
}
/**
* See header
*/
tls_prf_t *tls_prf_create_12(pseudo_random_function_t prf)
{
private_tls_prf12_t *this;
INIT(this,
.public = {
.set_key = _set_key12,
.get_bytes = _get_bytes12,
.destroy = _destroy12,
},
.prf = lib->crypto->create_prf(lib->crypto, prf),
);
if (!this->prf)
{
free(this);
return NULL;
}
return &this->public;
}
typedef struct private_tls_prf10_t private_tls_prf10_t;
/**
* Private data of an tls_prf_t object.
*/
struct private_tls_prf10_t {
/**
* Public tls_prf_t interface.
*/
tls_prf_t public;
/**
* Underlying MD5 PRF
*/
prf_t *md5;
/**
* Underlying SHA1 PRF
*/
prf_t *sha1;
};
METHOD(tls_prf_t, set_key10, bool,
private_tls_prf10_t *this, chunk_t key)
{
size_t len = key.len / 2 + key.len % 2;
return this->md5->set_key(this->md5, chunk_create(key.ptr, len)) &&
this->sha1->set_key(this->sha1, chunk_create(key.ptr + key.len - len,
len));
}
METHOD(tls_prf_t, get_bytes10, bool,
private_tls_prf10_t *this, char *label, chunk_t seed,
size_t bytes, char *out)
{
char buf[bytes];
if (!p_hash(this->md5, label, seed, this->md5->get_block_size(this->md5),
bytes, out) ||
!p_hash(this->sha1, label, seed, this->sha1->get_block_size(this->sha1),
bytes, buf))
{
return FALSE;
}
memxor(out, buf, bytes);
return TRUE;
}
METHOD(tls_prf_t, destroy10, void,
private_tls_prf10_t *this)
{
DESTROY_IF(this->md5);
DESTROY_IF(this->sha1);
free(this);
}
/**
* See header
*/
tls_prf_t *tls_prf_create_10(pseudo_random_function_t prf)
{
private_tls_prf10_t *this;
INIT(this,
.public = {
.set_key = _set_key10,
.get_bytes = _get_bytes10,
.destroy = _destroy10,
},
.md5 = lib->crypto->create_prf(lib->crypto, PRF_HMAC_MD5),
.sha1 = lib->crypto->create_prf(lib->crypto, PRF_HMAC_SHA1),
);
if (!this->md5 || !this->sha1)
{
destroy10(this);
return NULL;
}
return &this->public;
}
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