mbedtls/programs/psa/aead_cipher_psa.c

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/*
* This is a simple example of multi-part AEAD computation using both the old
* Cipher API and the new PSA API; its goal is to help migration to PSA Crypto.
*
* Copyright The Mbed TLS Contributors
* 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.
*/
/*
* When used with multi-part AEAD operations, the `mbedtls_cipher_context`
* serves a triple purpose (1) hold the key, (2) store the algorithm when no
* operation is active, and (3) save progress information for the current
* operation. With PSA those roles are held by disinct objects: (1) a
* psa_key_id_t to hold the key, a (2) psa_algorithm_t to represent the
* algorithm, and (3) a psa_operation_t for multi-part progress.
*
* On the other hand, with PSA, the algorithms encodes the desired tag length;
* with Cipher the desired tag length needs to be tracked separately.
*
* This program illustrates this by doing the same sequence of multi-part AEAD
* computation with both APIs; looking at the two series of functions
* cipher_xxx() and aead_xxx() side by side should make the differences and
* similarities clear.
*/
#include <stdio.h>
#include "mbedtls/build_info.h"
#if !defined(MBEDTLS_PSA_CRYPTO_C) || !defined(MBEDTLS_CIPHER_C) || \
!defined(MBEDTLS_AES_C) || !defined(MBEDTLS_GCM_C) || \
!defined(MBEDTLS_CHACHAPOLY_C) || \
defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)
int main( void )
{
printf( "MBEDTLS_PSA_CRYPTO_C and/or MBEDTLS_MD_C and/or "
"MBEDTLS_AES_C and/or MBEDTLS_GCM_C and/or "
"MBEDTLS_CHACHAPOLY_C not defined, and/or "
"MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER defined\r\n" );
return( 0 );
}
#else
#include <string.h>
#include "mbedtls/cipher.h"
#include "psa/crypto.h"
/*
* Common data and helper functions
*/
const char usage[] = "Usage: aead_cipher_psa [aes128-gcm|aes256-gcm|aes128-gcm_8|chachapoly]";
const unsigned char iv1[12] = { 0x00 };
const unsigned char add_data1[] = { 0x01, 0x02 };
const unsigned char msg1_part1[] = { 0x03, 0x04 };
const unsigned char msg1_part2[] = { 0x05, 0x06, 0x07 };
const size_t msg1_size = sizeof( msg1_part1 ) + sizeof( msg1_part2 );
const unsigned char iv2[12] = { 0x10 };
const unsigned char add_data2[] = { 0x11, 0x12 };
const unsigned char msg2_part1[] = { 0x13, 0x14 };
const unsigned char msg2_part2[] = { 0x15, 0x16, 0x17 };
const size_t msg2_size = sizeof( msg2_part1 ) + sizeof( msg2_part2 );
const size_t msg_max_size = msg1_size > msg2_size ? msg1_size : msg2_size;
const unsigned char key_bytes[32] = { 0x2a };
void print_out( const char *title, unsigned char *out, size_t len )
{
printf( "%s:", title );
for( size_t i = 0; i < len; i++ )
printf( " %02x", out[i] );
printf( "\n" );
}
/*
* Functions using the Cipher API
*/
#define CHK( code ) \
do { \
ret = code; \
if( ret != 0 ) { \
printf( "%03d: ret = -0x%04x\n", __LINE__, (unsigned) -ret ); \
goto exit; \
} \
} while( 0 )
static int cipher_prepare( const char *info,
mbedtls_cipher_context_t *ctx,
size_t *tag_len )
{
int ret;
mbedtls_cipher_type_t type;
if( strcmp( info, "aes128-gcm" ) == 0 ) {
type = MBEDTLS_CIPHER_AES_128_GCM;
*tag_len = 16;
} else if( strcmp( info, "aes256-gcm" ) == 0 ) {
type = MBEDTLS_CIPHER_AES_256_GCM;
*tag_len = 16;
} else if( strcmp( info, "aes128-gcm_8" ) == 0 ) {
type = MBEDTLS_CIPHER_AES_128_GCM;
*tag_len = 8;
} else if( strcmp( info, "chachapoly" ) == 0 ) {
type = MBEDTLS_CIPHER_CHACHA20_POLY1305;
*tag_len = 16;
} else {
puts( usage );
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
}
CHK( mbedtls_cipher_setup( ctx,
mbedtls_cipher_info_from_type( type ) ) );
int key_len = mbedtls_cipher_get_key_bitlen( ctx );
CHK( mbedtls_cipher_setkey( ctx, key_bytes, key_len, MBEDTLS_ENCRYPT ) );
exit:
return( ret );
}
static void cipher_info( const mbedtls_cipher_context_t *ctx, size_t tag_len )
{
// no convenient way to get the cipher type (for example, AES)
const char *ciph = "???";
int key_bits = mbedtls_cipher_get_key_bitlen( ctx );
mbedtls_cipher_mode_t mode = mbedtls_cipher_get_cipher_mode( ctx );
const char *mode_str = mode == MBEDTLS_MODE_GCM ? "GCM"
: mode == MBEDTLS_MODE_CHACHAPOLY ? "ChachaPoly"
: "???";
printf( "cipher: %s, %d, %s, %u\n", ciph, key_bits, mode_str, (unsigned) tag_len );
}
static int cipher_encrypt( mbedtls_cipher_context_t *ctx, size_t tag_len,
const unsigned char *iv, size_t iv_len,
const unsigned char *ad, size_t ad_len,
const unsigned char *pa, size_t pa_len,
const unsigned char *pb, size_t pb_len )
{
int ret;
size_t olen;
unsigned char out[msg_max_size + 16];
unsigned char *p = out;
CHK( mbedtls_cipher_set_iv( ctx, iv, iv_len ) );
CHK( mbedtls_cipher_reset( ctx ) );
CHK( mbedtls_cipher_update_ad( ctx, ad, ad_len ) );
CHK( mbedtls_cipher_update( ctx, pa, pa_len, p, &olen ) );
p += olen;
CHK( mbedtls_cipher_update( ctx, pb, pb_len, p, &olen ) );
p += olen;
CHK( mbedtls_cipher_finish( ctx, p, &olen ) );
p += olen;
CHK( mbedtls_cipher_write_tag( ctx, p, tag_len ) );
p += tag_len;
olen = p - out;
print_out( "cipher", out, olen );
exit:
return( ret );
}
static int cipher( const char *info )
{
int ret = 0;
mbedtls_cipher_context_t ctx;
size_t tag_len;
mbedtls_cipher_init( &ctx );
CHK( cipher_prepare( info, &ctx, &tag_len ) );
cipher_info( &ctx, tag_len );
CHK( cipher_encrypt( &ctx, tag_len,
iv1, sizeof( iv1 ), add_data1, sizeof( add_data1 ),
msg1_part1, sizeof( msg1_part1 ),
msg1_part2, sizeof( msg1_part2 ) ) );
CHK( cipher_encrypt( &ctx, tag_len,
iv2, sizeof( iv2 ), add_data2, sizeof( add_data2 ),
msg2_part1, sizeof( msg2_part1 ),
msg2_part2, sizeof( msg2_part2 ) ) );
exit:
mbedtls_cipher_free( &ctx );
return( ret );
}
#undef CHK
/*
* Functions using the PSA Crypto API
*/
#define CHK( code ) \
do { \
status = code; \
if( status != PSA_SUCCESS ) { \
printf( "%03d: status = %d\n", __LINE__, status ); \
goto exit; \
} \
} while( 0 )
static psa_status_t aead_prepare( const char *info,
psa_key_id_t *key,
psa_algorithm_t *alg )
{
psa_status_t status;
size_t key_bits;
psa_key_type_t key_type;
if( strcmp( info, "aes128-gcm" ) == 0 ) {
*alg = PSA_ALG_GCM;
key_bits = 128;
key_type = PSA_KEY_TYPE_AES;
} else if( strcmp( info, "aes256-gcm" ) == 0 ) {
*alg = PSA_ALG_GCM;
key_bits = 256;
key_type = PSA_KEY_TYPE_AES;
} else if( strcmp( info, "aes128-gcm_8" ) == 0 ) {
*alg = PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_GCM, 8);
key_bits = 128;
key_type = PSA_KEY_TYPE_AES;
} else if( strcmp( info, "chachapoly" ) == 0 ) {
*alg = PSA_ALG_CHACHA20_POLY1305;
key_bits = 256;
key_type = PSA_KEY_TYPE_CHACHA20;
} else {
puts( usage );
return( PSA_ERROR_INVALID_ARGUMENT );
}
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT );
psa_set_key_algorithm( &attributes, *alg );
psa_set_key_type( &attributes, key_type );
psa_set_key_bits( &attributes, key_bits );
CHK( psa_import_key( &attributes, key_bytes, key_bits / 8, key ) );
exit:
return( status );
}
static void aead_info( psa_key_id_t key, psa_algorithm_t alg )
{
psa_key_attributes_t attr = PSA_KEY_ATTRIBUTES_INIT;
(void) psa_get_key_attributes( key, &attr );
psa_key_type_t key_type = psa_get_key_type( &attr );
size_t key_bits = psa_get_key_bits( &attr );
psa_algorithm_t base_alg = PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG( alg );
size_t tag_len = PSA_AEAD_TAG_LENGTH( key_type, key_bits, alg );
const char *type_str = key_type == PSA_KEY_TYPE_AES ? "AES"
: key_type == PSA_KEY_TYPE_CHACHA20 ? "Chacha"
: "???";
const char *base_str = base_alg == PSA_ALG_GCM ? "GCM"
: base_alg == PSA_ALG_CHACHA20_POLY1305 ? "ChachaPoly"
: "???";
printf( "aead : %s, %u, %s, %u\n",
type_str, (unsigned) key_bits, base_str, (unsigned) tag_len );
}
static int aead_encrypt( psa_key_id_t key, psa_algorithm_t alg,
const unsigned char *iv, size_t iv_len,
const unsigned char *ad, size_t ad_len,
const unsigned char *pa, size_t pa_len,
const unsigned char *pb, size_t pb_len )
{
psa_status_t status;
size_t olen, olen_tag;
unsigned char out[PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE(msg_max_size)];
unsigned char *p = out, *end = out + sizeof( out );
unsigned char tag[PSA_AEAD_TAG_MAX_SIZE];
psa_aead_operation_t op = PSA_AEAD_OPERATION_INIT;
CHK( psa_aead_encrypt_setup( &op, key, alg ) );
CHK( psa_aead_set_nonce( &op, iv, iv_len ) );
CHK( psa_aead_update_ad( &op, ad, ad_len ) );
CHK( psa_aead_update( &op, pa, pa_len, p, end - p, &olen ) );
p += olen;
CHK( psa_aead_update( &op, pb, pb_len, p, end - p, &olen ) );
p += olen;
CHK( psa_aead_finish( &op, p, end - p, &olen,
tag, sizeof( tag ), &olen_tag ) );
p += olen;
memcpy( p, tag, olen_tag );
p += olen_tag;
olen = p - out;
print_out( "aead ", out, olen );
exit:
/* required on errors, harmless on success */
psa_aead_abort( &op );
return( status );
}
static psa_status_t aead( const char *info )
{
psa_status_t status;
psa_key_id_t key;
psa_algorithm_t alg;
CHK( aead_prepare( info, &key, &alg ) );
aead_info( key, alg );
CHK( aead_encrypt( key, alg,
iv1, sizeof( iv1 ), add_data1, sizeof( add_data1 ),
msg1_part1, sizeof( msg1_part1 ),
msg1_part2, sizeof( msg1_part2 ) ) );
CHK( aead_encrypt( key, alg,
iv2, sizeof( iv2 ), add_data2, sizeof( add_data2 ),
msg2_part1, sizeof( msg2_part1 ),
msg2_part2, sizeof( msg2_part2 ) ) );
exit:
psa_destroy_key( key );
return( status );
}
#undef CHK
/*
* Main function
*/
int main( int argc, char **argv )
{
if( argc != 2 )
{
puts( usage );
return( 1 );
}
psa_crypto_init();
cipher( argv[1] );
aead( argv[1] );
}
#endif