174 lines
3.5 KiB
C
174 lines
3.5 KiB
C
/*
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* Copyright (C) 2016 Andreas Steffen
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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 "chapoly_xof.h"
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#include "chapoly_drv.h"
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typedef struct private_chapoly_xof_t private_chapoly_xof_t;
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/**
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* Private data of an chapoly_xof_t object.
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*/
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struct private_chapoly_xof_t {
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/**
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* Public chapoly_xof_t interface.
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*/
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chapoly_xof_t public;
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/**
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* Latest block of the ChaCha20 stream.
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*/
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uint8_t stream[CHACHA_BLOCK_SIZE];
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/**
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* Index pointing to the current position in the stream
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*/
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u_int stream_index;
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/**
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* Driver backend
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*/
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chapoly_drv_t *drv;
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};
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METHOD(xof_t, get_type, ext_out_function_t,
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private_chapoly_xof_t *this)
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{
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return XOF_CHACHA20;
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}
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METHOD(xof_t, get_bytes, bool,
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private_chapoly_xof_t *this, size_t out_len, uint8_t *buffer)
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{
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size_t index = 0, len, blocks;
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/* empty the stream buffer first */
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len = min(out_len, CHACHA_BLOCK_SIZE - this->stream_index);
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if (len)
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{
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memcpy(buffer, this->stream + this->stream_index, len);
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index += len;
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this->stream_index += len;
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}
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/* copy whole stream blocks directly to output buffer */
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blocks = (out_len - index) / CHACHA_BLOCK_SIZE;
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while (blocks--)
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{
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if (!this->drv->chacha(this->drv, buffer + index))
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{
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return FALSE;
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}
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index += CHACHA_BLOCK_SIZE;
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}
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/* refill the stream buffer if some more output bytes are needed */
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len = out_len - index;
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if (len)
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{
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if (!this->drv->chacha(this->drv, this->stream))
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{
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return FALSE;
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}
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memcpy(buffer + index, this->stream, len);
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this->stream_index = len;
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}
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return TRUE;
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}
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METHOD(xof_t, allocate_bytes, bool,
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private_chapoly_xof_t *this, size_t out_len, chunk_t *chunk)
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{
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*chunk = chunk_alloc(out_len);
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if (!get_bytes(this, out_len, 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(xof_t, get_block_size, size_t,
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private_chapoly_xof_t *this)
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{
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return CHACHA_BLOCK_SIZE;
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}
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METHOD(xof_t, get_seed_size, size_t,
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private_chapoly_xof_t *this)
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{
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return CHACHA_KEY_SIZE + CHACHA_SALT_SIZE + CHACHA_IV_SIZE;
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}
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METHOD(xof_t, set_seed, bool,
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private_chapoly_xof_t *this, chunk_t seed)
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{
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this->stream_index = CHACHA_BLOCK_SIZE;
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return seed.len == get_seed_size(this) &&
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this->drv->set_key(this->drv, "expand 32-byte k",
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seed.ptr, seed.ptr + CHACHA_KEY_SIZE) &&
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this->drv->init(this->drv,
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seed.ptr + CHACHA_KEY_SIZE + CHACHA_SALT_SIZE);
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}
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METHOD(xof_t, destroy, void,
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private_chapoly_xof_t *this)
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{
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this->drv->destroy(this->drv);
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free(this);
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}
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/**
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* See header
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*/
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chapoly_xof_t *chapoly_xof_create(ext_out_function_t algorithm)
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{
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private_chapoly_xof_t *this;
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chapoly_drv_t *drv;
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if (algorithm != XOF_CHACHA20)
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{
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return NULL;
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}
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drv = chapoly_drv_probe();
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if (!drv)
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{
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return NULL;
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}
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INIT(this,
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.public = {
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.xof_interface = {
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.get_type = _get_type,
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.get_bytes = _get_bytes,
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.allocate_bytes = _allocate_bytes,
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.get_block_size = _get_block_size,
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.get_seed_size = _get_seed_size,
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.set_seed = _set_seed,
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.destroy = _destroy,
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},
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},
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.drv = drv,
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);
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return &this->public;
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}
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