/*
* Copyright (C) 2020 Tobias Brunner
* HSR Hochschule fuer Technik Rapperswil
*
* 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 <openssl/evp.h>
/* SHA3 was added with 1.1.1 */
#if OPENSSL_VERSION_NUMBER >= 0x1010100fL && !defined(OPENSSL_NO_SHAKE)
#include "openssl_xof.h"
#define KECCAK_STATE_SIZE 200 /* 1600 bits*/
typedef struct private_xof_t private_xof_t;
/**
* Private data
*/
struct private_xof_t {
/**
* Public interface.
*/
xof_t public;
/**
* XOF algorithm to be used
*/
ext_out_function_t algorithm;
/**
* Internal type reference
*/
const EVP_MD *md;
/**
* Internal context
*/
EVP_MD_CTX *ctx;
/**
* Current seed
*/
chunk_t seed;
/**
* Offset into generated data
*/
size_t offset;
};
METHOD(xof_t, get_type, ext_out_function_t,
private_xof_t *this)
{
return this->algorithm;
}
METHOD(xof_t, get_bytes, bool,
private_xof_t *this, size_t out_len, uint8_t *buffer)
{
bool success = FALSE;
chunk_t data;
/* we can call EVP_DigestFinalXOF() only once, so to support an arbitrary
* number of calls to get_bytes(), we request all the data we already
* requested previously and just ignore what we already handed out */
if (EVP_DigestInit_ex(this->ctx, this->md, NULL) == 1 &&
EVP_DigestUpdate(this->ctx, this->seed.ptr, this->seed.len) == 1)
{
data = chunk_alloc(out_len + this->offset);
if (EVP_DigestFinalXOF(this->ctx, data.ptr, data.len) == 1)
{
memcpy(buffer, data.ptr + this->offset, out_len);
this->offset += out_len;
success = TRUE;
}
chunk_clear(&data);
}
return success;
}
METHOD(xof_t, allocate_bytes, bool,
private_xof_t *this, size_t out_len, chunk_t *chunk)
{
*chunk = chunk_alloc(out_len);
return get_bytes(this, out_len, chunk->ptr);
}
METHOD(xof_t, get_block_size, size_t,
private_xof_t *this)
{
return EVP_MD_block_size(this->md);
}
METHOD(xof_t, get_seed_size, size_t,
private_xof_t *this)
{
return KECCAK_STATE_SIZE - EVP_MD_block_size(this->md);
}
METHOD(xof_t, set_seed, bool,
private_xof_t *this, chunk_t seed)
{
chunk_clear(&this->seed);
this->seed = chunk_clone(seed);
this->offset = 0;
return TRUE;
}
METHOD(xof_t, destroy, void,
private_xof_t *this)
{
EVP_MD_CTX_free(this->ctx);
chunk_clear(&this->seed);
free(this);
}
/*
* Described in header
*/
xof_t *openssl_xof_create(ext_out_function_t algorithm)
{
private_xof_t *this;
const EVP_MD *md;
switch (algorithm)
{
case XOF_SHAKE_128:
md = EVP_shake128();
break;
case XOF_SHAKE_256:
md = EVP_shake256();
break;
default:
return NULL;
}
INIT(this,
.public = {
.get_type = _get_type,
.get_bytes = _get_bytes,
.allocate_bytes = _allocate_bytes,
.get_block_size = _get_block_size,
.get_seed_size = _get_seed_size,
.set_seed = _set_seed,
.destroy = _destroy,
},
.algorithm = algorithm,
.md = md,
.ctx = EVP_MD_CTX_new(),
);
return &this->public;
}
#endif /* OPENSSL_NO_ECDH */
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