171 lines
3.5 KiB
C
171 lines
3.5 KiB
C
/*
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* Copyright (C) 2005-2006 Martin Willi
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* Copyright (C) 2005 Jan Hutter
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* HSR Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <string.h>
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#include "prf_plus.h"
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typedef struct private_prf_plus_t private_prf_plus_t;
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typedef bool (*apply_prf_t)(private_prf_plus_t *this);
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/**
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* Private data of an prf_plus_t object.
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*
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*/
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struct private_prf_plus_t {
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/**
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* Public interface of prf_plus_t.
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*/
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prf_plus_t public;
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/**
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* PRF to use.
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*/
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prf_t *prf;
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/**
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* Initial seed.
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*/
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chunk_t seed;
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/**
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* Octet which will be appended to the seed if a counter is used.
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*/
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uint8_t counter;
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/**
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* Already given out bytes in current buffer.
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*/
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size_t used;
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/**
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* Buffer to store current PRF result.
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*/
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chunk_t buffer;
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/**
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* The prf application method depending on whether a counter is used.
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*/
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apply_prf_t apply_prf;
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};
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/**
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* Apply the PRF using the running counter
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*/
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static bool apply_prf_counter(private_prf_plus_t *this)
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{
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if (!this->prf->get_bytes(this->prf, this->seed, NULL) ||
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!this->prf->get_bytes(this->prf, chunk_from_thing(this->counter),
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this->buffer.ptr))
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{
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return FALSE;
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}
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this->counter++;
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if (!this->counter)
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{ /* according to RFC 7296, section 2.13, prf+ is undefined once the
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* counter wrapped, so let's fail for future calls */
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this->apply_prf = (void*)return_false;
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}
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return TRUE;
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}
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/**
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* Apply the PRF using the running counter
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*/
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static bool apply_prf(private_prf_plus_t *this)
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{
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return this->prf->get_bytes(this->prf, this->seed, this->buffer.ptr);
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}
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METHOD(prf_plus_t, get_bytes, bool,
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private_prf_plus_t *this, size_t length, uint8_t *buffer)
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{
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size_t round, written = 0;
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while (length > 0)
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{
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if (this->buffer.len == this->used)
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{ /* buffer used, get next round */
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if (!this->prf->get_bytes(this->prf, this->buffer, NULL))
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{
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return FALSE;
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}
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if (!this->apply_prf(this))
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{
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return FALSE;
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}
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this->used = 0;
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}
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round = min(length, this->buffer.len - this->used);
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memcpy(buffer + written, this->buffer.ptr + this->used, round);
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length -= round;
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this->used += round;
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written += round;
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}
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return TRUE;
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}
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METHOD(prf_plus_t, allocate_bytes, bool,
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private_prf_plus_t *this, size_t length, chunk_t *chunk)
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{
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*chunk = chunk_alloc(length);
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if (!get_bytes(this, length, chunk->ptr))
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{
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chunk_free(chunk);
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return FALSE;
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}
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return TRUE;
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}
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METHOD(prf_plus_t, destroy, void,
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private_prf_plus_t *this)
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{
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chunk_clear(&this->buffer);
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chunk_clear(&this->seed);
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free(this);
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}
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/*
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* Description in header.
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*/
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prf_plus_t *prf_plus_create(prf_t *prf, bool counter, chunk_t seed)
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{
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private_prf_plus_t *this;
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INIT(this,
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.public = {
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.get_bytes = _get_bytes,
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.allocate_bytes = _allocate_bytes,
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.destroy = _destroy,
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},
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.prf = prf,
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.seed = chunk_clone(seed),
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.buffer = chunk_alloc(prf->get_block_size(prf)),
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.apply_prf = counter ? apply_prf_counter : apply_prf,
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.counter = 0x01,
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);
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if (!this->apply_prf(this))
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{
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destroy(this);
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return NULL;
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}
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return &this->public;
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}
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