157 lines
3.7 KiB
C
157 lines
3.7 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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* 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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/**
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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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* 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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* Already given out bytes in current buffer.
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*/
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size_t given_out;
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/**
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* Octet which will be appended to the seed.
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*/
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u_int8_t appending_octet;
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};
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/**
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* Implementation of prf_plus_t.get_bytes.
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*/
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static void get_bytes(private_prf_plus_t *this, size_t length, u_int8_t *buffer)
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{
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chunk_t appending_chunk;
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size_t bytes_in_round;
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size_t total_bytes_written = 0;
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appending_chunk.ptr = &(this->appending_octet);
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appending_chunk.len = 1;
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while (length > 0)
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{ /* still more to do... */
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if (this->buffer.len == this->given_out)
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{ /* no bytes left in buffer, get next*/
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this->prf->get_bytes(this->prf, this->buffer, NULL);
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this->prf->get_bytes(this->prf, this->seed, NULL);
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this->prf->get_bytes(this->prf, appending_chunk, this->buffer.ptr);
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this->given_out = 0;
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this->appending_octet++;
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}
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/* how many bytes can we write in this round ? */
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bytes_in_round = min(length, this->buffer.len - this->given_out);
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/* copy bytes from buffer with offset */
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memcpy(buffer + total_bytes_written, this->buffer.ptr + this->given_out, bytes_in_round);
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length -= bytes_in_round;
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this->given_out += bytes_in_round;
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total_bytes_written += bytes_in_round;
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}
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}
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/**
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* Implementation of prf_plus_t.allocate_bytes.
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*/
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static void allocate_bytes(private_prf_plus_t *this, size_t length, chunk_t *chunk)
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{
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if (length)
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{
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chunk->ptr = malloc(length);
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chunk->len = length;
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get_bytes(this, length, chunk->ptr);
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}
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else
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{
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*chunk = chunk_empty;
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}
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}
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/**
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* Implementation of prf_plus_t.destroy.
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*/
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static void destroy(private_prf_plus_t *this)
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{
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free(this->buffer.ptr);
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free(this->seed.ptr);
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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, chunk_t seed)
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{
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private_prf_plus_t *this;
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chunk_t appending_chunk;
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this = malloc_thing(private_prf_plus_t);
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/* set public methods */
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this->public.get_bytes = (void (*)(prf_plus_t *,size_t,u_int8_t*))get_bytes;
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this->public.allocate_bytes = (void (*)(prf_plus_t *,size_t,chunk_t*))allocate_bytes;
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this->public.destroy = (void (*)(prf_plus_t *))destroy;
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/* take over prf */
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this->prf = prf;
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/* allocate buffer for prf output */
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this->buffer.len = prf->get_block_size(prf);
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this->buffer.ptr = malloc(this->buffer.len);
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this->appending_octet = 0x01;
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/* clone seed */
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this->seed.ptr = clalloc(seed.ptr, seed.len);
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this->seed.len = seed.len;
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/* do the first run */
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appending_chunk.ptr = &(this->appending_octet);
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appending_chunk.len = 1;
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this->prf->get_bytes(this->prf, this->seed, NULL);
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this->prf->get_bytes(this->prf, appending_chunk, this->buffer.ptr);
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this->given_out = 0;
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this->appending_octet++;
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return &(this->public);
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}
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