/*
* aes_cbc.c
*
* AES Cipher Block Chaining Mode
*
* David A. McGrew
* Cisco Systems, Inc.
*/
/*
*
* Copyright (c) 2001-2006, Cisco Systems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* Neither the name of the Cisco Systems, Inc. nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "aes_cbc.h"
#include "alloc.h"
debug_module_t mod_aes_cbc = {
0, /* debugging is off by default */
"aes cbc" /* printable module name */
};
err_status_t
aes_cbc_alloc(cipher_t **c, int key_len) {
extern cipher_type_t aes_cbc;
uint8_t *pointer;
int tmp;
debug_print(mod_aes_cbc,
"allocating cipher with key length %d", key_len);
if (key_len != 16)
return err_status_bad_param;
/* allocate memory a cipher of type aes_icm */
tmp = (sizeof(aes_cbc_ctx_t) + sizeof(cipher_t));
pointer = (uint8_t*)crypto_alloc(tmp);
if (pointer == NULL)
return err_status_alloc_fail;
/* set pointers */
*c = (cipher_t *)pointer;
(*c)->type = &aes_cbc;
(*c)->state = pointer + sizeof(cipher_t);
/* increment ref_count */
aes_cbc.ref_count++;
/* set key size */
(*c)->key_len = key_len;
return err_status_ok;
}
err_status_t
aes_cbc_dealloc(cipher_t *c) {
extern cipher_type_t aes_cbc;
/* zeroize entire state*/
octet_string_set_to_zero((uint8_t *)c,
sizeof(aes_cbc_ctx_t) + sizeof(cipher_t));
/* free memory */
crypto_free(c);
/* decrement ref_count */
aes_cbc.ref_count--;
return err_status_ok;
}
err_status_t
aes_cbc_context_init(aes_cbc_ctx_t *c, const uint8_t *key,
cipher_direction_t dir) {
v128_t tmp_key;
/* set tmp_key (for alignment) */
v128_copy_octet_string(&tmp_key, key);
debug_print(mod_aes_cbc,
"key: %s", v128_hex_string(&tmp_key));
/* expand key for the appropriate direction */
switch (dir) {
case (direction_encrypt):
aes_expand_encryption_key(&tmp_key, c->expanded_key);
break;
case (direction_decrypt):
aes_expand_decryption_key(&tmp_key, c->expanded_key);
break;
default:
return err_status_bad_param;
}
return err_status_ok;
}
err_status_t
aes_cbc_set_iv(aes_cbc_ctx_t *c, void *iv) {
int i;
/* v128_t *input = iv; */
uint8_t *input = (uint8_t*) iv;
/* set state and 'previous' block to iv */
for (i=0; i < 16; i++)
c->previous.v8[i] = c->state.v8[i] = input[i];
debug_print(mod_aes_cbc, "setting iv: %s", v128_hex_string(&c->state));
return err_status_ok;
}
err_status_t
aes_cbc_encrypt(aes_cbc_ctx_t *c,
unsigned char *data,
unsigned int *bytes_in_data) {
int i;
unsigned char *input = data; /* pointer to data being read */
unsigned char *output = data; /* pointer to data being written */
int bytes_to_encr = *bytes_in_data;
/*
* verify that we're 16-octet aligned
*/
if (*bytes_in_data & 0xf)
return err_status_bad_param;
/*
* note that we assume that the initialization vector has already
* been set, e.g. by calling aes_cbc_set_iv()
*/
debug_print(mod_aes_cbc, "iv: %s",
v128_hex_string(&c->state));
/*
* loop over plaintext blocks, exoring state into plaintext then
* encrypting and writing to output
*/
while (bytes_to_encr > 0) {
/* exor plaintext into state */
for (i=0; i < 16; i++)
c->state.v8[i] ^= *input++;
debug_print(mod_aes_cbc, "inblock: %s",
v128_hex_string(&c->state));
aes_encrypt(&c->state, c->expanded_key);
debug_print(mod_aes_cbc, "outblock: %s",
v128_hex_string(&c->state));
/* copy ciphertext to output */
for (i=0; i < 16; i++)
*output++ = c->state.v8[i];
bytes_to_encr -= 16;
}
return err_status_ok;
}
err_status_t
aes_cbc_decrypt(aes_cbc_ctx_t *c,
unsigned char *data,
unsigned int *bytes_in_data) {
int i;
v128_t state, previous;
unsigned char *input = data; /* pointer to data being read */
unsigned char *output = data; /* pointer to data being written */
int bytes_to_encr = *bytes_in_data;
uint8_t tmp;
/*
* verify that we're 16-octet aligned
*/
if (*bytes_in_data & 0x0f)
return err_status_bad_param;
/* set 'previous' block to iv*/
for (i=0; i < 16; i++) {
previous.v8[i] = c->previous.v8[i];
}
debug_print(mod_aes_cbc, "iv: %s",
v128_hex_string(&previous));
/*
* loop over ciphertext blocks, decrypting then exoring with state
* then writing plaintext to output
*/
while (bytes_to_encr > 0) {
/* set state to ciphertext input block */
for (i=0; i < 16; i++) {
state.v8[i] = *input++;
}
debug_print(mod_aes_cbc, "inblock: %s",
v128_hex_string(&state));
/* decrypt state */
aes_decrypt(&state, c->expanded_key);
debug_print(mod_aes_cbc, "outblock: %s",
v128_hex_string(&state));
/*
* exor previous ciphertext block out of plaintext, and write new
* plaintext block to output, while copying old ciphertext block
* to the 'previous' block
*/
for (i=0; i < 16; i++) {
tmp = *output;
*output++ = state.v8[i] ^ previous.v8[i];
previous.v8[i] = tmp;
}
bytes_to_encr -= 16;
}
return err_status_ok;
}
err_status_t
aes_cbc_nist_encrypt(aes_cbc_ctx_t *c,
unsigned char *data,
unsigned int *bytes_in_data) {
int i;
unsigned char *pad_start;
int num_pad_bytes;
err_status_t status;
/*
* determine the number of padding bytes that we need to add -
* this value is always between 1 and 16, inclusive.
*/
num_pad_bytes = 16 - (*bytes_in_data & 0xf);
pad_start = data;
pad_start += *bytes_in_data;
*pad_start++ = 0xa0;
for (i=0; i < num_pad_bytes; i++)
*pad_start++ = 0x00;
/*
* increment the data size
*/
*bytes_in_data += num_pad_bytes;
/*
* now cbc encrypt the padded data
*/
status = aes_cbc_encrypt(c, data, bytes_in_data);
if (status)
return status;
return err_status_ok;
}
err_status_t
aes_cbc_nist_decrypt(aes_cbc_ctx_t *c,
unsigned char *data,
unsigned int *bytes_in_data) {
unsigned char *pad_end;
int num_pad_bytes;
err_status_t status;
/*
* cbc decrypt the padded data
*/
status = aes_cbc_decrypt(c, data, bytes_in_data);
if (status)
return status;
/*
* determine the number of padding bytes in the decrypted plaintext
* - this value is always between 1 and 16, inclusive.
*/
num_pad_bytes = 1;
pad_end = data + (*bytes_in_data - 1);
while (*pad_end != 0xa0) { /* note: should check padding correctness */
pad_end--;
num_pad_bytes++;
}
/* decrement data size */
*bytes_in_data -= num_pad_bytes;
return err_status_ok;
}
char
aes_cbc_description[] = "aes cipher block chaining (cbc) mode";
/*
* Test case 0 is derived from FIPS 197 Appendix A; it uses an
* all-zero IV, so that the first block encryption matches the test
* case in that appendix. This property provides a check of the base
* AES encryption and decryption algorithms; if CBC fails on some
* particular platform, then you should print out AES intermediate
* data and compare with the detailed info provided in that appendix.
*
*/
uint8_t aes_cbc_test_case_0_key[16] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f
};
uint8_t aes_cbc_test_case_0_plaintext[64] = {
0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff
};
uint8_t aes_cbc_test_case_0_ciphertext[80] = {
0x69, 0xc4, 0xe0, 0xd8, 0x6a, 0x7b, 0x04, 0x30,
0xd8, 0xcd, 0xb7, 0x80, 0x70, 0xb4, 0xc5, 0x5a,
0x03, 0x35, 0xed, 0x27, 0x67, 0xf2, 0x6d, 0xf1,
0x64, 0x83, 0x2e, 0x23, 0x44, 0x38, 0x70, 0x8b
};
uint8_t aes_cbc_test_case_0_iv[16] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
cipher_test_case_t aes_cbc_test_case_0 = {
16, /* octets in key */
aes_cbc_test_case_0_key, /* key */
aes_cbc_test_case_0_iv, /* initialization vector */
16, /* octets in plaintext */
aes_cbc_test_case_0_plaintext, /* plaintext */
32, /* octets in ciphertext */
aes_cbc_test_case_0_ciphertext, /* ciphertext */
NULL /* pointer to next testcase */
};
/*
* this test case is taken directly from Appendix F.2 of NIST Special
* Publication SP 800-38A
*/
uint8_t aes_cbc_test_case_1_key[16] = {
0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c,
};
uint8_t aes_cbc_test_case_1_plaintext[64] = {
0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c,
0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11,
0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17,
0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10
};
uint8_t aes_cbc_test_case_1_ciphertext[80] = {
0x76, 0x49, 0xab, 0xac, 0x81, 0x19, 0xb2, 0x46,
0xce, 0xe9, 0x8e, 0x9b, 0x12, 0xe9, 0x19, 0x7d,
0x50, 0x86, 0xcb, 0x9b, 0x50, 0x72, 0x19, 0xee,
0x95, 0xdb, 0x11, 0x3a, 0x91, 0x76, 0x78, 0xb2,
0x73, 0xbe, 0xd6, 0xb8, 0xe3, 0xc1, 0x74, 0x3b,
0x71, 0x16, 0xe6, 0x9e, 0x22, 0x22, 0x95, 0x16,
0x3f, 0xf1, 0xca, 0xa1, 0x68, 0x1f, 0xac, 0x09,
0x12, 0x0e, 0xca, 0x30, 0x75, 0x86, 0xe1, 0xa7,
0x39, 0x34, 0x07, 0x03, 0x36, 0xd0, 0x77, 0x99,
0xe0, 0xc4, 0x2f, 0xdd, 0xa8, 0xdf, 0x4c, 0xa3
};
uint8_t aes_cbc_test_case_1_iv[16] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f
};
cipher_test_case_t aes_cbc_test_case_1 = {
16, /* octets in key */
aes_cbc_test_case_1_key, /* key */
aes_cbc_test_case_1_iv, /* initialization vector */
64, /* octets in plaintext */
aes_cbc_test_case_1_plaintext, /* plaintext */
80, /* octets in ciphertext */
aes_cbc_test_case_1_ciphertext, /* ciphertext */
&aes_cbc_test_case_0 /* pointer to next testcase */
};
cipher_type_t aes_cbc = {
(cipher_alloc_func_t) aes_cbc_alloc,
(cipher_dealloc_func_t) aes_cbc_dealloc,
(cipher_init_func_t) aes_cbc_context_init,
(cipher_encrypt_func_t) aes_cbc_nist_encrypt,
(cipher_decrypt_func_t) aes_cbc_nist_decrypt,
(cipher_set_iv_func_t) aes_cbc_set_iv,
(char *) aes_cbc_description,
(int) 0, /* instance count */
(cipher_test_case_t *) &aes_cbc_test_case_0,
(debug_module_t *) &mod_aes_cbc
};