programs/psa/crypto_examples.c

#include "psa/crypto.h"
#include <string.h>

#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#endif

#define ASSERT( predicate )                                                   \
    do                                                                        \
    {                                                                         \
        if( ! ( predicate ) )                                                 \
        {                                                                     \
            mbedtls_printf( "\tassertion failed at %s:%d - '%s'\r\n",         \
                            __FILE__, __LINE__, #predicate);                  \
            goto exit;                                                        \
        }                                                                     \
    } while ( 0 )

#define ASSERT_STATUS( actual, expected )                                     \
    do                                                                        \
    {                                                                         \
        if( ( actual ) != ( expected ) )                                      \
        {                                                                     \
            mbedtls_printf( "\tassertion failed at %s:%d - "                  \
                            "actual:%d expected:%d\r\n", __FILE__, __LINE__,  \
                            (psa_status_t) actual, (psa_status_t) expected ); \
            goto exit;                                                        \
        }                                                                     \
    } while ( 0 )

/* Use key slot 1 for our cipher key. Key slot 0 is reserved as unused. */
static const psa_key_slot_t key_slot_cipher = 1;

static psa_status_t set_key_policy( psa_key_slot_t key_slot,
                                    psa_key_usage_t key_usage,
                                    psa_algorithm_t alg )
{
    psa_status_t status;
    psa_key_policy_t policy;

    psa_key_policy_init( &policy );
    psa_key_policy_set_usage( &policy, key_usage, alg );
    status = psa_set_key_policy( key_slot, &policy );
    ASSERT_STATUS( status, PSA_SUCCESS );
exit:
    return( status );
}

static psa_status_t cipher_operation( psa_cipher_operation_t *operation,
                                      const uint8_t * input,
                                      size_t input_size,
                                      size_t part_size,
                                      uint8_t * output,
                                      size_t output_size,
                                      size_t *output_len )
{
    psa_status_t status;
    size_t bytes_to_write = 0, bytes_written = 0, len = 0;

    *output_len = 0;
    while( bytes_written != input_size )
    {
        bytes_to_write = ( input_size - bytes_written > part_size ?
                           part_size :
                           input_size - bytes_written );

        status = psa_cipher_update( operation, input + bytes_written,
                                    bytes_to_write, output + *output_len,
                                    output_size - *output_len, &len );
        ASSERT_STATUS( status, PSA_SUCCESS );

        bytes_written += bytes_to_write;
        *output_len += len;
    }

    status = psa_cipher_finish( operation, output + *output_len,
                                output_size - *output_len, &len );
    ASSERT_STATUS( status, PSA_SUCCESS );
    *output_len += len;

exit:
    return( status );
}

static psa_status_t cipher_encrypt( psa_key_slot_t key_slot,
                                    psa_algorithm_t alg,
                                    uint8_t * iv,
                                    size_t iv_size,
                                    const uint8_t * input,
                                    size_t input_size,
                                    size_t part_size,
                                    uint8_t * output,
                                    size_t output_size,
                                    size_t *output_len )
{
    psa_status_t status;
    psa_cipher_operation_t operation;
    size_t iv_len = 0;

    memset( &operation, 0, sizeof( operation ) );
    status = psa_cipher_encrypt_setup( &operation, key_slot, alg );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = psa_cipher_generate_iv( &operation, iv, iv_size, &iv_len );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = cipher_operation( &operation, input, input_size, part_size,
                               output, output_size, output_len );
    ASSERT_STATUS( status, PSA_SUCCESS );

exit:
    psa_cipher_abort( &operation );
    return( status );
}

static psa_status_t cipher_decrypt( psa_key_slot_t key_slot,
                                    psa_algorithm_t alg,
                                    const uint8_t * iv,
                                    size_t iv_size,
                                    const uint8_t * input,
                                    size_t input_size,
                                    size_t part_size,
                                    uint8_t * output,
                                    size_t output_size,
                                    size_t *output_len )
{
    psa_status_t status;
    psa_cipher_operation_t operation;

    memset( &operation, 0, sizeof( operation ) );
    status = psa_cipher_decrypt_setup( &operation, key_slot, alg );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = psa_cipher_set_iv( &operation, iv, iv_size );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = cipher_operation( &operation, input, input_size, part_size,
                               output, output_size, output_len );
    ASSERT_STATUS( status, PSA_SUCCESS );

exit:
    psa_cipher_abort( &operation );
    return( status );
}

static psa_status_t
cipher_example_encrypt_decrypt_aes_cbc_nopad_1_block( void )
{
    enum {
        block_size = PSA_BLOCK_CIPHER_BLOCK_SIZE( PSA_KEY_TYPE_AES ),
        key_bits = 256,
        part_size = block_size,
    };
    const psa_algorithm_t alg = PSA_ALG_CBC_BASE |
                                PSA_ALG_BLOCK_CIPHER_PAD_NONE;

    psa_status_t status;
    size_t output_len = 0;
    uint8_t iv[block_size];
    uint8_t input[block_size];
    uint8_t encrypt[block_size];
    uint8_t decrypt[block_size];

    status = psa_generate_random( input, sizeof( input ) );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = set_key_policy( key_slot_cipher,
                             PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_DECRYPT,
                             alg );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = psa_generate_key( key_slot_cipher, PSA_KEY_TYPE_AES, key_bits,
                               NULL, 0 );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = cipher_encrypt( key_slot_cipher, alg, iv, sizeof( iv ),
                             input, sizeof( input ), part_size,
                             encrypt, sizeof( encrypt ), &output_len );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = cipher_decrypt( key_slot_cipher, alg, iv, sizeof( iv ),
                             encrypt, output_len, part_size,
                             decrypt, sizeof( decrypt ), &output_len );
    ASSERT_STATUS( status, PSA_SUCCESS );

    status = memcmp( input, decrypt, sizeof( input ) );
    ASSERT_STATUS( status, PSA_SUCCESS );

exit:
    psa_destroy_key( key_slot_cipher );
    return( status );
}

static void cipher_examples( void )
{
    psa_status_t status;

    mbedtls_printf( "cipher encrypt/decrypt AES CBC no padding:\r\n" );
    status = cipher_example_encrypt_decrypt_aes_cbc_nopad_1_block( );
    if( status == PSA_SUCCESS )
        mbedtls_printf( "\tsuccess!\r\n" );
}

int main( void )
{
    ASSERT( psa_crypto_init( ) == PSA_SUCCESS );
    cipher_examples( );
exit:
    mbedtls_psa_crypto_free( );
    return( 0 );
}