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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 "af_alg_prf.h"
#include "af_alg_ops.h"
typedef struct private_af_alg_prf_t private_af_alg_prf_t;
/**
* Private data of a af_alg_prf_t object.
*/
struct private_af_alg_prf_t {
/**
* Public af_alg_prf_t interface.
*/
af_alg_prf_t public;
/**
* AF_ALG operations
*/
af_alg_ops_t *ops;
/**
* Size of the PRF output
*/
size_t block_size;
/**
* Default key size
*/
size_t key_size;
/**
* Using an XCBC algorithm?
*/
bool xcbc;
};
/**
* Algorithm database
*/
static struct {
pseudo_random_function_t id;
char *name;
size_t block_size;
bool xcbc;
} algs[AF_ALG_PRF] = {
{PRF_HMAC_SHA1, "hmac(sha1)", 20, FALSE, },
{PRF_HMAC_SHA2_256, "hmac(sha256)", 32, FALSE, },
{PRF_HMAC_MD5, "hmac(md5)", 16, FALSE, },
{PRF_HMAC_SHA2_384, "hmac(sha384)", 48, FALSE, },
{PRF_HMAC_SHA2_512, "hmac(sha512)", 64, FALSE, },
{PRF_AES128_XCBC, "xcbc(aes)", 16, TRUE, },
{PRF_CAMELLIA128_XCBC, "xcbc(camellia)", 16, TRUE, },
};
/**
* See header.
*/
void af_alg_prf_probe(plugin_feature_t *features, int *pos)
{
af_alg_ops_t *ops;
int i;
for (i = 0; i < countof(algs); i++)
{
ops = af_alg_ops_create("hash", algs[i].name);
if (ops)
{
ops->destroy(ops);
features[(*pos)++] = PLUGIN_PROVIDE(PRF, algs[i].id);
}
}
}
/**
* Get the kernel algorithm string and block size for our identifier
*/
static size_t lookup_alg(pseudo_random_function_t algo, char **name, bool *xcbc)
{
int i;
for (i = 0; i < countof(algs); i++)
{
if (algs[i].id == algo)
{
*name = algs[i].name;
*xcbc = algs[i].xcbc;
return algs[i].block_size;
}
}
return 0;
}
METHOD(prf_t, get_bytes, void,
private_af_alg_prf_t *this, chunk_t seed, u_int8_t *buffer)
{
this->ops->hash(this->ops, seed, buffer, this->block_size);
}
METHOD(prf_t, allocate_bytes, void,
private_af_alg_prf_t *this, chunk_t seed, chunk_t *chunk)
{
if (chunk)
{
*chunk = chunk_alloc(this->block_size);
get_bytes(this, seed, chunk->ptr);
}
else
{
get_bytes(this, seed, NULL);
}
}
METHOD(prf_t, get_block_size, size_t,
private_af_alg_prf_t *this)
{
return this->block_size;
}
METHOD(prf_t, get_key_size, size_t,
private_af_alg_prf_t *this)
{
return this->block_size;
}
METHOD(prf_t, set_key, void,
private_af_alg_prf_t *this, chunk_t key)
{
char buf[this->block_size];
if (this->xcbc)
{
/* The kernel currently does not support variable length XCBC keys,
* do RFC4434 key padding/reduction manually. */
if (key.len < this->block_size)
{
memset(buf, 0, this->block_size);
memcpy(buf, key.ptr, key.len);
key = chunk_from_thing(buf);
}
else if (key.len > this->block_size)
{
memset(buf, 0, this->block_size);
this->ops->set_key(this->ops, chunk_from_thing(buf));
this->ops->hash(this->ops, key, buf, this->block_size);
key = chunk_from_thing(buf);
}
}
this->ops->set_key(this->ops, key);
}
METHOD(prf_t, destroy, void,
private_af_alg_prf_t *this)
{
this->ops->destroy(this->ops);
free(this);
}
/*
* Described in header.
*/
af_alg_prf_t *af_alg_prf_create(pseudo_random_function_t algo)
{
private_af_alg_prf_t *this;
size_t block_size;
bool xcbc;
char *name;
block_size = lookup_alg(algo, &name, &xcbc);
if (!block_size)
{ /* not supported by kernel */
return NULL;
}
INIT(this,
.public = {
.prf = {
.get_bytes = _get_bytes,
.allocate_bytes = _allocate_bytes,
.get_block_size = _get_block_size,
.get_key_size = _get_key_size,
.set_key = _set_key,
.destroy = _destroy,
},
},
.ops = af_alg_ops_create("hash", name),
.block_size = block_size,
.xcbc = xcbc,
);
if (!this->ops)
{
free(this);
return NULL;
}
return &this->public;
}
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