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/*
* Copyright (C) 2008 Tobias Brunner
* 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 "openssl_crypter.h"
#include <openssl/evp.h>
typedef struct private_openssl_crypter_t private_openssl_crypter_t;
/**
* Private data of openssl_crypter_t
*/
struct private_openssl_crypter_t {
/**
* Public part of this class.
*/
openssl_crypter_t public;
/*
* the key
*/
chunk_t key;
/*
* the cipher to use
*/
const EVP_CIPHER *cipher;
};
/**
* Look up an OpenSSL algorithm name and validate its key size
*/
static char* lookup_algorithm(u_int16_t ikev2_algo, size_t *key_size)
{
struct {
/* identifier specified in IKEv2 */
int ikev2_id;
/* name of the algorithm, as used in OpenSSL */
char *name;
/* default key size in bytes */
size_t key_def;
/* minimum key size */
size_t key_min;
/* maximum key size */
size_t key_max;
} mappings[] = {
{ENCR_DES, "des", 8, 8, 8},
{ENCR_3DES, "des3", 24, 24, 24},
{ENCR_RC5, "rc5", 16, 5, 255},
{ENCR_IDEA, "idea", 16, 16, 16},
{ENCR_CAST, "cast", 16, 5, 16},
{ENCR_BLOWFISH, "blowfish", 16, 5, 56},
};
int i;
for (i = 0; i < countof(mappings); i++)
{
if (ikev2_algo == mappings[i].ikev2_id)
{
/* set the key size if it is not set */
if (*key_size == 0)
{
*key_size = mappings[i].key_def;
}
/* validate key size */
if (*key_size < mappings[i].key_min ||
*key_size > mappings[i].key_max)
{
return NULL;
}
return mappings[i].name;
}
}
return NULL;
}
/**
* Do the actual en/decryption in an EVP context
*/
static void crypt(private_openssl_crypter_t *this, chunk_t data, chunk_t iv,
chunk_t *dst, int enc)
{
int len;
u_char *out;
out = data.ptr;
if (dst)
{
*dst = chunk_alloc(data.len);
out = dst->ptr;
}
EVP_CIPHER_CTX ctx;
EVP_CIPHER_CTX_init(&ctx);
EVP_CipherInit_ex(&ctx, this->cipher, NULL, NULL, NULL, enc);
EVP_CIPHER_CTX_set_padding(&ctx, 0); /* disable padding */
EVP_CIPHER_CTX_set_key_length(&ctx, this->key.len);
EVP_CipherInit_ex(&ctx, NULL, NULL, this->key.ptr, iv.ptr, enc);
EVP_CipherUpdate(&ctx, out, &len, data.ptr, data.len);
EVP_CipherFinal_ex(&ctx, out + len, &len); /* since padding is disabled this does nothing */
EVP_CIPHER_CTX_cleanup(&ctx);
}
METHOD(crypter_t, decrypt, void,
private_openssl_crypter_t *this, chunk_t data, chunk_t iv, chunk_t *dst)
{
crypt(this, data, iv, dst, 0);
}
METHOD(crypter_t, encrypt, void,
private_openssl_crypter_t *this, chunk_t data, chunk_t iv, chunk_t *dst)
{
crypt(this, data, iv, dst, 1);
}
METHOD(crypter_t, get_block_size, size_t,
private_openssl_crypter_t *this)
{
return this->cipher->block_size;
}
METHOD(crypter_t, get_iv_size, size_t,
private_openssl_crypter_t *this)
{
return this->cipher->block_size;
}
METHOD(crypter_t, get_key_size, size_t,
private_openssl_crypter_t *this)
{
return this->key.len;
}
METHOD(crypter_t, set_key, void,
private_openssl_crypter_t *this, chunk_t key)
{
memcpy(this->key.ptr, key.ptr, min(key.len, this->key.len));
}
METHOD(crypter_t, destroy, void,
private_openssl_crypter_t *this)
{
chunk_clear(&this->key);
free(this);
}
/*
* Described in header
*/
openssl_crypter_t *openssl_crypter_create(encryption_algorithm_t algo,
size_t key_size)
{
private_openssl_crypter_t *this;
INIT(this,
.public = {
.crypter = {
.encrypt = _encrypt,
.decrypt = _decrypt,
.get_block_size = _get_block_size,
.get_iv_size = _get_iv_size,
.get_key_size = _get_key_size,
.set_key = _set_key,
.destroy = _destroy,
},
},
);
switch (algo)
{
case ENCR_NULL:
this->cipher = EVP_enc_null();
key_size = 0;
break;
case ENCR_AES_CBC:
switch (key_size)
{
case 0:
key_size = 16;
/* FALL */
case 16: /* AES 128 */
this->cipher = EVP_get_cipherbyname("aes128");
break;
case 24: /* AES-192 */
this->cipher = EVP_get_cipherbyname("aes192");
break;
case 32: /* AES-256 */
this->cipher = EVP_get_cipherbyname("aes256");
break;
default:
free(this);
return NULL;
}
break;
case ENCR_CAMELLIA_CBC:
switch (key_size)
{
case 0:
key_size = 16;
/* FALL */
case 16: /* CAMELLIA 128 */
this->cipher = EVP_get_cipherbyname("camellia128");
break;
case 24: /* CAMELLIA 192 */
this->cipher = EVP_get_cipherbyname("camellia192");
break;
case 32: /* CAMELLIA 256 */
this->cipher = EVP_get_cipherbyname("camellia256");
break;
default:
free(this);
return NULL;
}
break;
case ENCR_DES_ECB:
key_size = 8;
this->cipher = EVP_des_ecb();
break;
default:
{
char* name;
name = lookup_algorithm(algo, &key_size);
if (!name)
{
/* algo unavailable or key_size invalid */
free(this);
return NULL;
}
this->cipher = EVP_get_cipherbyname(name);
break;
}
}
if (!this->cipher)
{
/* OpenSSL does not support the requested algo */
free(this);
return NULL;
}
this->key = chunk_alloc(key_size);
return &this->public;
}
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