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/*
* Copyright (C) 2005-2006 Martin Willi
* Copyright (C) 2005 Jan Hutter
* 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 <string.h>
#include "prf_plus.h"
typedef struct private_prf_plus_t private_prf_plus_t;
/**
* Private data of an prf_plus_t object.
*
*/
struct private_prf_plus_t {
/**
* Public interface of prf_plus_t.
*/
prf_plus_t public;
/**
* PRF to use.
*/
prf_t *prf;
/**
* Initial seed.
*/
chunk_t seed;
/**
* Octet which will be appended to the seed, 0 if not used
*/
uint8_t counter;
/**
* Already given out bytes in current buffer.
*/
size_t used;
/**
* Buffer to store current PRF result.
*/
chunk_t buffer;
};
METHOD(prf_plus_t, get_bytes, bool,
private_prf_plus_t *this, size_t length, uint8_t *buffer)
{
size_t round, written = 0;
while (length > 0)
{
if (this->buffer.len == this->used)
{ /* buffer used, get next round */
if (!this->prf->get_bytes(this->prf, this->buffer, NULL))
{
return FALSE;
}
if (this->counter)
{
if (!this->prf->get_bytes(this->prf, this->seed, NULL) ||
!this->prf->get_bytes(this->prf,
chunk_from_thing(this->counter), this->buffer.ptr))
{
return FALSE;
}
this->counter++;
}
else
{
if (!this->prf->get_bytes(this->prf, this->seed,
this->buffer.ptr))
{
return FALSE;
}
}
this->used = 0;
}
round = min(length, this->buffer.len - this->used);
memcpy(buffer + written, this->buffer.ptr + this->used, round);
length -= round;
this->used += round;
written += round;
}
return TRUE;
}
METHOD(prf_plus_t, allocate_bytes, bool,
private_prf_plus_t *this, size_t length, chunk_t *chunk)
{
if (length)
{
*chunk = chunk_alloc(length);
return get_bytes(this, length, chunk->ptr);
}
*chunk = chunk_empty;
return TRUE;
}
METHOD(prf_plus_t, destroy, void,
private_prf_plus_t *this)
{
chunk_clear(&this->buffer);
chunk_clear(&this->seed);
free(this);
}
/*
* Description in header.
*/
prf_plus_t *prf_plus_create(prf_t *prf, bool counter, chunk_t seed)
{
private_prf_plus_t *this;
INIT(this,
.public = {
.get_bytes = _get_bytes,
.allocate_bytes = _allocate_bytes,
.destroy = _destroy,
},
.prf = prf,
.seed = chunk_clone(seed),
.buffer = chunk_alloc(prf->get_block_size(prf)),
);
if (counter)
{
this->counter = 0x01;
if (!this->prf->get_bytes(this->prf, this->seed, NULL) ||
!this->prf->get_bytes(this->prf, chunk_from_thing(this->counter),
this->buffer.ptr))
{
destroy(this);
return NULL;
}
this->counter++;
}
else
{
if (!this->prf->get_bytes(this->prf, this->seed, this->buffer.ptr))
{
destroy(this);
return NULL;
}
}
return &this->public;
}
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