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/*
* Copyright (C) JuanJo Ciarlante <jjo-ipsec@mendoza.gov.ar>
* Copyright (C) 2005-2006 Martin Willi
* Copyright (C) 2009 Andreas Steffen
* 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 "serpent_crypter.h"
#include "serpent.h"
#define SERPENT_BLOCK_SIZE 16
typedef struct private_serpent_crypter_t private_serpent_crypter_t;
/**
* Class implementing the AES symmetric encryption algorithm.
*
* @ingroup crypters
*/
struct private_serpent_crypter_t {
/**
* Public part of this class.
*/
serpent_crypter_t public;
/**
* Serpent context
*/
serpent_context serpent_ctx;
/**
* Key size of this Serpent cipher object.
*/
u_int32_t key_size;
};
/**
* Implementation of crypter_t.encrypt.
*/
static void encrypt(private_serpent_crypter_t *this, chunk_t data, chunk_t iv,
chunk_t *encrypted)
{
int pos = 0;
u_int8_t *in, *out;
if (encrypted)
{
*encrypted = chunk_alloc(data.len);
out = encrypted->ptr;
}
else
{
out = data.ptr;
}
in = data.ptr;
while ( pos < data.len)
{
const u_int32_t *iv_i;
iv_i = (pos) ? (const u_int32_t*)(out - 16) :
(const u_int32_t*)(iv.ptr);
*((u_int32_t *)(&out[ 0])) = iv_i[0] ^ *((const u_int32_t *)(&in[ 0]));
*((u_int32_t *)(&out[ 4])) = iv_i[1] ^ *((const u_int32_t *)(&in[ 4]));
*((u_int32_t *)(&out[ 8])) = iv_i[2] ^ *((const u_int32_t *)(&in[ 8]));
*((u_int32_t *)(&out[12])) = iv_i[3] ^ *((const u_int32_t *)(&in[12]));
serpent_encrypt(&this->serpent_ctx, out, out);
in += SERPENT_BLOCK_SIZE;
out += SERPENT_BLOCK_SIZE;
pos += SERPENT_BLOCK_SIZE;
}
}
/**
* Implementation of crypter_t.decrypt.
*/
static void decrypt(private_serpent_crypter_t *this, chunk_t data, chunk_t iv,
chunk_t *decrypted)
{
int pos = data.len - SERPENT_BLOCK_SIZE;
u_int8_t *in, *out;
if (decrypted)
{
*decrypted = chunk_alloc(data.len);
out = decrypted->ptr;
}
else
{
out = data.ptr;
}
in = data.ptr;
in += pos;
out += pos;
while (pos >= 0)
{
const u_int32_t *iv_i;
serpent_decrypt(&this->serpent_ctx, in, out);
iv_i = (pos) ? (const u_int32_t*)(in - 16) :
(const u_int32_t*)(iv.ptr);
*((u_int32_t *)(&out[ 0])) ^= iv_i[0];
*((u_int32_t *)(&out[ 4])) ^= iv_i[1];
*((u_int32_t *)(&out[ 8])) ^= iv_i[2];
*((u_int32_t *)(&out[12])) ^= iv_i[3];
in -= SERPENT_BLOCK_SIZE;
out -= SERPENT_BLOCK_SIZE;
pos -= SERPENT_BLOCK_SIZE;
}
}
/**
* Implementation of crypter_t.get_block_size.
*/
static size_t get_block_size (private_serpent_crypter_t *this)
{
return SERPENT_BLOCK_SIZE;
}
/**
* Implementation of crypter_t.get_key_size.
*/
static size_t get_key_size (private_serpent_crypter_t *this)
{
return this->key_size;
}
/**
* Implementation of crypter_t.set_key.
*/
static void set_key (private_serpent_crypter_t *this, chunk_t key)
{
serpent_set_key(&this->serpent_ctx, key.ptr, key.len);
}
/**
* Implementation of crypter_t.destroy and serpent_crypter_t.destroy.
*/
static void destroy (private_serpent_crypter_t *this)
{
free(this);
}
/*
* Described in header
*/
serpent_crypter_t *serpent_crypter_create(encryption_algorithm_t algo, size_t key_size)
{
private_serpent_crypter_t *this;
if (algo != ENCR_SERPENT_CBC || !(key_size == 16 || key_size == 32))
{
return NULL;
}
this = malloc_thing(private_serpent_crypter_t);
this->public.crypter_interface.encrypt = (void (*) (crypter_t *, chunk_t,chunk_t, chunk_t *)) encrypt;
this->public.crypter_interface.decrypt = (void (*) (crypter_t *, chunk_t , chunk_t, chunk_t *)) decrypt;
this->public.crypter_interface.get_block_size = (size_t (*) (crypter_t *)) get_block_size;
this->public.crypter_interface.get_key_size = (size_t (*) (crypter_t *)) get_key_size;
this->public.crypter_interface.set_key = (void (*) (crypter_t *,chunk_t)) set_key;
this->public.crypter_interface.destroy = (void (*) (crypter_t *)) destroy;
return &(this->public);
}
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