OVMS3-idf/components/esp32/aes.c

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/*
* FIPS-197 compliant AES implementation
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
/*
* The AES block cipher was designed by Vincent Rijmen and Joan Daemen.
*
* http://csrc.nist.gov/encryption/aes/rijndael/Rijndael.pdf
* http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
*/
#include <string.h>
#include "aes.h"
#include "esp_crypto.h"
/* Implementation that should never be optimized out by the compiler */
//static void bzero( void *v, size_t n ) {
// volatile unsigned char *p = v; while( n-- ) *p++ = 0;
//}
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void esp_aes_init( AES_CTX *ctx )
{
memset( ctx, 0, sizeof( AES_CTX ) );
AES_LOCK();
AES_TAKE();
ets_aes_enable();
AES_UNLOCK();
}
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void esp_aes_free( AES_CTX *ctx )
{
if( ctx == NULL )
return;
bzero( ctx, sizeof( AES_CTX ) );
AES_LOCK();
AES_GIVE();
if (false == AES_IS_USED())
ets_aes_disable();
AES_UNLOCK();
}
/*
* AES key schedule (encryption)
*/
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int esp_aes_setkey_enc( AES_CTX *ctx, const unsigned char *key,
unsigned int keybits )
{
enum AES_BITS keybit;
uint16_t keybyte = keybits / 8;
switch (keybits){
case 128:
keybit = AES128;
break;
case 192:
keybit = AES192;
break;
case 256:
keybit = AES256;
break;
default : return( ERR_AES_INVALID_KEY_LENGTH );
}
if (ctx->enc.keyflag == false){
ctx->enc.keyflag = true;
ctx->enc.keybits = keybits;
memset(ctx->enc.key, 0, sizeof(ctx->enc.key));
memcpy(ctx->enc.key, key, keybyte);
} else {
ets_aes_setkey_enc(key, keybit);
}
return 0;
}
/*
* AES key schedule (decryption)
*/
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int esp_aes_setkey_dec( AES_CTX *ctx, const unsigned char *key,
unsigned int keybits )
{
enum AES_BITS keybit;
uint16_t keybyte = keybits / 8;
switch (keybits){
case 128:
keybit = AES128;
break;
case 192:
keybit = AES192;
break;
case 256:
keybit = AES256;
break;
default : return( ERR_AES_INVALID_KEY_LENGTH );
}
if (ctx->dec.keyflag == false){
ctx->dec.keyflag = true;
ctx->dec.keybits = keybits;
memset(ctx->dec.key, 0, sizeof(ctx->dec.key));
memcpy(ctx->dec.key, key, keybyte);
} else {
ets_aes_setkey_dec(key, keybit);
}
return 0;
}
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static void esp_aes_process_enable(AES_CTX *ctx, int mode)
{
if( mode == AES_ENCRYPT ){
esp_aes_setkey_enc(ctx, ctx->enc.key, ctx->enc.keybits);
}else{
esp_aes_setkey_dec(ctx, ctx->dec.key, ctx->dec.keybits);
}
return;
}
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static void esp_aes_process_disable(AES_CTX *ctx, int mode)
{
}
/*
* AES-ECB block encryption
*/
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void esp_aes_encrypt( AES_CTX *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
ets_aes_crypt(input, output);
return ;
}
/*
* AES-ECB block decryption
*/
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void esp_aes_decrypt( AES_CTX *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
ets_aes_crypt(input, output);
return ;
}
/*
* AES-ECB block encryption/decryption
*/
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int esp_aes_crypt_ecb( AES_CTX *ctx,
int mode,
const unsigned char input[16],
unsigned char output[16] )
{
AES_LOCK();
esp_aes_process_enable(ctx, mode);
if( mode == AES_ENCRYPT )
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esp_aes_encrypt( ctx, input, output );
else
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esp_aes_decrypt( ctx, input, output );
esp_aes_process_disable(ctx, mode);
AES_UNLOCK();
return 0;
}
/*
* AES-CBC buffer encryption/decryption
*/
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int esp_aes_crypt_cbc( AES_CTX *ctx,
int mode,
size_t length,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
{
int i;
unsigned char temp[16];
if( length % 16 )
return( ERR_AES_INVALID_INPUT_LENGTH );
if( mode == AES_DECRYPT )
{
while( length > 0 )
{
memcpy( temp, input, 16 );
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esp_aes_crypt_ecb( ctx, mode, input, output );
for( i = 0; i < 16; i++ )
output[i] = (unsigned char)( output[i] ^ iv[i] );
memcpy( iv, temp, 16 );
input += 16;
output += 16;
length -= 16;
}
}
else
{
while( length > 0 )
{
for( i = 0; i < 16; i++ )
output[i] = (unsigned char)( input[i] ^ iv[i] );
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esp_aes_crypt_ecb( ctx, mode, output, output );
memcpy( iv, output, 16 );
input += 16;
output += 16;
length -= 16;
}
}
return 0;
}
/*
* AES-CFB128 buffer encryption/decryption
*/
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int esp_aes_crypt_cfb128( AES_CTX *ctx,
int mode,
size_t length,
size_t *iv_off,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
{
int c;
size_t n = *iv_off;
if( mode == AES_DECRYPT )
{
while( length-- )
{
if( n == 0 )
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esp_aes_crypt_ecb( ctx, AES_ENCRYPT, iv, iv );
c = *input++;
*output++ = (unsigned char)( c ^ iv[n] );
iv[n] = (unsigned char) c;
n = ( n + 1 ) & 0x0F;
}
}
else
{
while( length-- )
{
if( n == 0 )
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esp_aes_crypt_ecb( ctx, AES_ENCRYPT, iv, iv );
iv[n] = *output++ = (unsigned char)( iv[n] ^ *input++ );
n = ( n + 1 ) & 0x0F;
}
}
*iv_off = n;
return 0;
}
/*
* AES-CFB8 buffer encryption/decryption
*/
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int esp_aes_crypt_cfb8( AES_CTX *ctx,
int mode,
size_t length,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
{
unsigned char c;
unsigned char ov[17];
while( length-- )
{
memcpy( ov, iv, 16 );
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esp_aes_crypt_ecb( ctx, AES_ENCRYPT, iv, iv );
if( mode == AES_DECRYPT )
ov[16] = *input;
c = *output++ = (unsigned char)( iv[0] ^ *input++ );
if( mode == AES_ENCRYPT )
ov[16] = c;
memcpy( iv, ov + 1, 16 );
}
return 0;
}
/*
* AES-CTR buffer encryption/decryption
*/
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int esp_aes_crypt_ctr( AES_CTX *ctx,
size_t length,
size_t *nc_off,
unsigned char nonce_counter[16],
unsigned char stream_block[16],
const unsigned char *input,
unsigned char *output )
{
int c, i;
size_t n = *nc_off;
while( length-- )
{
if( n == 0 ) {
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esp_aes_crypt_ecb( ctx, AES_ENCRYPT, nonce_counter, stream_block );
for( i = 16; i > 0; i-- )
if( ++nonce_counter[i - 1] != 0 )
break;
}
c = *input++;
*output++ = (unsigned char)( c ^ stream_block[n] );
n = ( n + 1 ) & 0x0F;
}
*nc_off = n;
return 0;
}