OVMS3-idf/components/esp32/aes.c

/*
 *  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;
//}

void esp_aes_init( AES_CTX *ctx )
{
    memset( ctx, 0, sizeof( AES_CTX ) );

    AES_LOCK();
    AES_TAKE();
	ets_aes_enable();
	AES_UNLOCK();
}

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)
 */
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)
 */
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;

}

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;
}

static void esp_aes_process_disable(AES_CTX *ctx, int mode)
{
	
}

/*
 * AES-ECB block encryption
 */

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
 */

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
 */
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 )
        esp_aes_encrypt( ctx, input, output );
    else
        esp_aes_decrypt( ctx, input, output );

	esp_aes_process_disable(ctx, mode);
	
	AES_UNLOCK();
	
	return 0;
}


/*
 * AES-CBC buffer encryption/decryption
 */
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 );
            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] );

            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
 */
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 )
				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 )
				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
 */
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 );
		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
 */
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 ) {
            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;
}