704 lines
		
	
	
		
			26 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
		
		
			
		
	
	
			704 lines
		
	
	
		
			26 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
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								/**
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								 * PSA API key derivation demonstration
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								 *
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								 * This program calculates a key ladder: a chain of secret material, each
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								 * derived from the previous one in a deterministic way based on a label.
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								 * Two keys are identical if and only if they are derived from the same key
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								 * using the same label.
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								 *
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								 * The initial key is called the master key. The master key is normally
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								 * randomly generated, but it could itself be derived from another key.
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								 *
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								 * This program derives a series of keys called intermediate keys.
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								 * The first intermediate key is derived from the master key using the
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								 * first label passed on the command line. Each subsequent intermediate
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								 * key is derived from the previous one using the next label passed
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								 * on the command line.
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								 *
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								 * This program has four modes of operation:
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								 *
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								 * - "generate": generate a random master key.
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								 * - "wrap": derive a wrapping key from the last intermediate key,
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								 *           and use that key to encrypt-and-authenticate some data.
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								 * - "unwrap": derive a wrapping key from the last intermediate key,
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								 *             and use that key to decrypt-and-authenticate some
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								 *             ciphertext created by wrap mode.
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								 * - "save": save the last intermediate key so that it can be reused as
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								 *           the master key in another run of the program.
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								 *
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								 * See the usage() output for the command line usage. See the file
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								 * `key_ladder_demo.sh` for an example run.
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								 */
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								/*
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								 *  Copyright The Mbed TLS Contributors
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								 *  SPDX-License-Identifier: Apache-2.0
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								 *
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								 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
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								 *  not use this file except in compliance with the License.
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								 *  You may obtain a copy of the License at
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								 *
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								 *  http://www.apache.org/licenses/LICENSE-2.0
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								 *
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								 *  Unless required by applicable law or agreed to in writing, software
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								 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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								 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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								 *  See the License for the specific language governing permissions and
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								 *  limitations under the License.
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								 */
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								/* First include Mbed TLS headers to get the Mbed TLS configuration and
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								 * platform definitions that we'll use in this program. Also include
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								 * standard C headers for functions we'll use here. */
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								#include "mbedtls/build_info.h"
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								#include <stdlib.h>
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								#include <stdio.h>
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								#include <string.h>
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								#include "mbedtls/platform_util.h" // for mbedtls_platform_zeroize
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								#include <psa/crypto.h>
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								/* If the build options we need are not enabled, compile a placeholder. */
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								#if !defined(MBEDTLS_SHA256_C) || !defined(MBEDTLS_MD_C) ||      \
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								    !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_CCM_C) ||        \
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								    !defined(MBEDTLS_PSA_CRYPTO_C) || !defined(MBEDTLS_FS_IO) || \
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								    defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)
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								int main( void )
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								{
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								    printf( "MBEDTLS_SHA256_C and/or MBEDTLS_MD_C and/or "
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								            "MBEDTLS_AES_C and/or MBEDTLS_CCM_C and/or "
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								            "MBEDTLS_PSA_CRYPTO_C and/or MBEDTLS_FS_IO "
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								            "not defined and/or MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER "
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								            "defined.\n" );
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								    return( 0 );
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								}
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								#else
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								/* The real program starts here. */
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								/* Run a system function and bail out if it fails. */
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								#define SYS_CHECK( expr )                                       \
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								    do                                                          \
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								    {                                                           \
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								        if( ! ( expr ) )                                        \
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								        {                                                       \
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								            perror( #expr );                                    \
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								            status = DEMO_ERROR;                                \
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								            goto exit;                                          \
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								        }                                                       \
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								    }                                                           \
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								    while( 0 )
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								/* Run a PSA function and bail out if it fails. */
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								#define PSA_CHECK( expr )                                       \
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								    do                                                          \
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								    {                                                           \
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								        status = ( expr );                                      \
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								        if( status != PSA_SUCCESS )                             \
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								        {                                                       \
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								            printf( "Error %d at line %d: %s\n",                \
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								                    (int) status,                               \
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								                    __LINE__,                                   \
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								                    #expr );                                    \
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								            goto exit;                                          \
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								        }                                                       \
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								    }                                                           \
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								    while( 0 )
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								/* To report operational errors in this program, use an error code that is
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								 * different from every PSA error code. */
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								#define DEMO_ERROR 120
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								/* The maximum supported key ladder depth. */
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								#define MAX_LADDER_DEPTH 10
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								/* Salt to use when deriving an intermediate key. */
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								#define DERIVE_KEY_SALT ( (uint8_t *) "key_ladder_demo.derive" )
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								#define DERIVE_KEY_SALT_LENGTH ( strlen( (const char*) DERIVE_KEY_SALT ) )
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								/* Salt to use when deriving a wrapping key. */
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								#define WRAPPING_KEY_SALT ( (uint8_t *) "key_ladder_demo.wrap" )
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								#define WRAPPING_KEY_SALT_LENGTH ( strlen( (const char*) WRAPPING_KEY_SALT ) )
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								/* Size of the key derivation keys (applies both to the master key and
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								 * to intermediate keys). */
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								#define KEY_SIZE_BYTES 40
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								/* Algorithm for key derivation. */
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								#define KDF_ALG PSA_ALG_HKDF( PSA_ALG_SHA_256 )
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								/* Type and size of the key used to wrap data. */
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								#define WRAPPING_KEY_TYPE PSA_KEY_TYPE_AES
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								#define WRAPPING_KEY_BITS 128
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								/* Cipher mode used to wrap data. */
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								#define WRAPPING_ALG PSA_ALG_CCM
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								/* Nonce size used to wrap data. */
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								#define WRAPPING_IV_SIZE 13
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								/* Header used in files containing wrapped data. We'll save this header
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								 * directly without worrying about data representation issues such as
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								 * integer sizes and endianness, because the data is meant to be read
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								 * back by the same program on the same machine. */
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								#define WRAPPED_DATA_MAGIC "key_ladder_demo" // including trailing null byte
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								#define WRAPPED_DATA_MAGIC_LENGTH ( sizeof( WRAPPED_DATA_MAGIC ) )
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								typedef struct
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								{
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								    char magic[WRAPPED_DATA_MAGIC_LENGTH];
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								    size_t ad_size; /* Size of the additional data, which is this header. */
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								    size_t payload_size; /* Size of the encrypted data. */
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								    /* Store the IV inside the additional data. It's convenient. */
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								    uint8_t iv[WRAPPING_IV_SIZE];
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								} wrapped_data_header_t;
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								/* The modes that this program can operate in (see usage). */
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								enum program_mode
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								{
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								    MODE_GENERATE,
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								    MODE_SAVE,
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								    MODE_UNWRAP,
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								    MODE_WRAP
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								};
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								/* Save a key to a file. In the real world, you may want to export a derived
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								 * key sometimes, to share it with another party. */
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								static psa_status_t save_key( psa_key_id_t key,
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								                              const char *output_file_name )
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								{
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								    psa_status_t status = PSA_SUCCESS;
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								    uint8_t key_data[KEY_SIZE_BYTES];
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								    size_t key_size;
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								    FILE *key_file = NULL;
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								    PSA_CHECK( psa_export_key( key,
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								                               key_data, sizeof( key_data ),
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								                               &key_size ) );
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								    SYS_CHECK( ( key_file = fopen( output_file_name, "wb" ) ) != NULL );
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								    SYS_CHECK( fwrite( key_data, 1, key_size, key_file ) == key_size );
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								    SYS_CHECK( fclose( key_file ) == 0 );
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								    key_file = NULL;
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								exit:
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								    if( key_file != NULL)
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								        fclose( key_file );
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								    return( status );
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								}
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								/* Generate a master key for use in this demo.
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								 *
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								 * Normally a master key would be non-exportable. For the purpose of this
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								 * demo, we want to save it to a file, to avoid relying on the keystore
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								 * capability of the PSA crypto library. */
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								static psa_status_t generate( const char *key_file_name )
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								{
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								    psa_status_t status = PSA_SUCCESS;
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								    psa_key_id_t key = 0;
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								    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
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								    psa_set_key_usage_flags( &attributes,
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								                             PSA_KEY_USAGE_DERIVE | PSA_KEY_USAGE_EXPORT );
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								    psa_set_key_algorithm( &attributes, KDF_ALG );
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								    psa_set_key_type( &attributes, PSA_KEY_TYPE_DERIVE );
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								    psa_set_key_bits( &attributes, PSA_BYTES_TO_BITS( KEY_SIZE_BYTES ) );
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								    PSA_CHECK( psa_generate_key( &attributes, &key ) );
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								    PSA_CHECK( save_key( key, key_file_name ) );
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								exit:
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								    (void) psa_destroy_key( key );
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								    return( status );
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								}
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								/* Load the master key from a file.
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								 *
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								 * In the real world, this master key would be stored in an internal memory
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								 * and the storage would be managed by the keystore capability of the PSA
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								 * crypto library. */
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								static psa_status_t import_key_from_file( psa_key_usage_t usage,
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								                                          psa_algorithm_t alg,
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								                                          const char *key_file_name,
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								                                          psa_key_id_t *master_key )
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								{
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								    psa_status_t status = PSA_SUCCESS;
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								    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
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								    uint8_t key_data[KEY_SIZE_BYTES];
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								    size_t key_size;
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								    FILE *key_file = NULL;
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								    unsigned char extra_byte;
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								    SYS_CHECK( ( key_file = fopen( key_file_name, "rb" ) ) != NULL );
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								    SYS_CHECK( ( key_size = fread( key_data, 1, sizeof( key_data ),
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								                                   key_file ) ) != 0 );
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								    if( fread( &extra_byte, 1, 1, key_file ) != 0 )
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								    {
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								        printf( "Key file too large (max: %u).\n",
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								                (unsigned) sizeof( key_data ) );
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								        status = DEMO_ERROR;
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								        goto exit;
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								    }
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								    SYS_CHECK( fclose( key_file ) == 0 );
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								    key_file = NULL;
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								    psa_set_key_usage_flags( &attributes, usage );
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								    psa_set_key_algorithm( &attributes, alg );
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								    psa_set_key_type( &attributes, PSA_KEY_TYPE_DERIVE );
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								    PSA_CHECK( psa_import_key( &attributes, key_data, key_size, master_key ) );
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| 
								 | 
							
								exit:
							 | 
						||
| 
								 | 
							
								    if( key_file != NULL )
							 | 
						||
| 
								 | 
							
								        fclose( key_file );
							 | 
						||
| 
								 | 
							
								    mbedtls_platform_zeroize( key_data, sizeof( key_data ) );
							 | 
						||
| 
								 | 
							
								    if( status != PSA_SUCCESS )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        /* If the key creation hasn't happened yet or has failed,
							 | 
						||
| 
								 | 
							
								         * *master_key is null. psa_destroy_key( 0 ) is
							 | 
						||
| 
								 | 
							
								         * guaranteed to do nothing and return PSA_SUCCESS. */
							 | 
						||
| 
								 | 
							
								        (void) psa_destroy_key( *master_key );
							 | 
						||
| 
								 | 
							
								        *master_key = 0;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								    return( status );
							 | 
						||
| 
								 | 
							
								}
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								/* Derive the intermediate keys, using the list of labels provided on
							 | 
						||
| 
								 | 
							
								 * the command line. On input, *key is the master key identifier.
							 | 
						||
| 
								 | 
							
								 * This function destroys the master key. On successful output, *key
							 | 
						||
| 
								 | 
							
								 * is the identifier of the final derived key.
							 | 
						||
| 
								 | 
							
								 */
							 | 
						||
| 
								 | 
							
								static psa_status_t derive_key_ladder( const char *ladder[],
							 | 
						||
| 
								 | 
							
								                                       size_t ladder_depth,
							 | 
						||
| 
								 | 
							
								                                       psa_key_id_t *key )
							 | 
						||
| 
								 | 
							
								{
							 | 
						||
| 
								 | 
							
								    psa_status_t status = PSA_SUCCESS;
							 | 
						||
| 
								 | 
							
								    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
							 | 
						||
| 
								 | 
							
								    psa_key_derivation_operation_t operation = PSA_KEY_DERIVATION_OPERATION_INIT;
							 | 
						||
| 
								 | 
							
								    size_t i;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    psa_set_key_usage_flags( &attributes,
							 | 
						||
| 
								 | 
							
								                             PSA_KEY_USAGE_DERIVE | PSA_KEY_USAGE_EXPORT );
							 | 
						||
| 
								 | 
							
								    psa_set_key_algorithm( &attributes, KDF_ALG );
							 | 
						||
| 
								 | 
							
								    psa_set_key_type( &attributes, PSA_KEY_TYPE_DERIVE );
							 | 
						||
| 
								 | 
							
								    psa_set_key_bits( &attributes, PSA_BYTES_TO_BITS( KEY_SIZE_BYTES ) );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* For each label in turn, ... */
							 | 
						||
| 
								 | 
							
								    for( i = 0; i < ladder_depth; i++ )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        /* Start deriving material from the master key (if i=0) or from
							 | 
						||
| 
								 | 
							
								         * the current intermediate key (if i>0). */
							 | 
						||
| 
								 | 
							
								        PSA_CHECK( psa_key_derivation_setup( &operation, KDF_ALG ) );
							 | 
						||
| 
								 | 
							
								        PSA_CHECK( psa_key_derivation_input_bytes(
							 | 
						||
| 
								 | 
							
								                       &operation, PSA_KEY_DERIVATION_INPUT_SALT,
							 | 
						||
| 
								 | 
							
								                       DERIVE_KEY_SALT, DERIVE_KEY_SALT_LENGTH ) );
							 | 
						||
| 
								 | 
							
								        PSA_CHECK( psa_key_derivation_input_key(
							 | 
						||
| 
								 | 
							
								                       &operation, PSA_KEY_DERIVATION_INPUT_SECRET,
							 | 
						||
| 
								 | 
							
								                       *key ) );
							 | 
						||
| 
								 | 
							
								        PSA_CHECK( psa_key_derivation_input_bytes(
							 | 
						||
| 
								 | 
							
								                       &operation, PSA_KEY_DERIVATION_INPUT_INFO,
							 | 
						||
| 
								 | 
							
								                       (uint8_t*) ladder[i], strlen( ladder[i] ) ) );
							 | 
						||
| 
								 | 
							
								        /* When the parent key is not the master key, destroy it,
							 | 
						||
| 
								 | 
							
								         * since it is no longer needed. */
							 | 
						||
| 
								 | 
							
								        PSA_CHECK( psa_destroy_key( *key ) );
							 | 
						||
| 
								 | 
							
								        *key = 0;
							 | 
						||
| 
								 | 
							
								        /* Derive the next intermediate key from the parent key. */
							 | 
						||
| 
								 | 
							
								        PSA_CHECK( psa_key_derivation_output_key( &attributes, &operation,
							 | 
						||
| 
								 | 
							
								                                                  key ) );
							 | 
						||
| 
								 | 
							
								        PSA_CHECK( psa_key_derivation_abort( &operation ) );
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								exit:
							 | 
						||
| 
								 | 
							
								    psa_key_derivation_abort( &operation );
							 | 
						||
| 
								 | 
							
								    if( status != PSA_SUCCESS )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        psa_destroy_key( *key );
							 | 
						||
| 
								 | 
							
								        *key = 0;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								    return( status );
							 | 
						||
| 
								 | 
							
								}
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								/* Derive a wrapping key from the last intermediate key. */
							 | 
						||
| 
								 | 
							
								static psa_status_t derive_wrapping_key( psa_key_usage_t usage,
							 | 
						||
| 
								 | 
							
								                                         psa_key_id_t derived_key,
							 | 
						||
| 
								 | 
							
								                                         psa_key_id_t *wrapping_key )
							 | 
						||
| 
								 | 
							
								{
							 | 
						||
| 
								 | 
							
								    psa_status_t status = PSA_SUCCESS;
							 | 
						||
| 
								 | 
							
								    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
							 | 
						||
| 
								 | 
							
								    psa_key_derivation_operation_t operation = PSA_KEY_DERIVATION_OPERATION_INIT;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    *wrapping_key = 0;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Set up a key derivation operation from the key derived from
							 | 
						||
| 
								 | 
							
								     * the master key. */
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_key_derivation_setup( &operation, KDF_ALG ) );
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_key_derivation_input_bytes(
							 | 
						||
| 
								 | 
							
								                   &operation, PSA_KEY_DERIVATION_INPUT_SALT,
							 | 
						||
| 
								 | 
							
								                   WRAPPING_KEY_SALT, WRAPPING_KEY_SALT_LENGTH ) );
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_key_derivation_input_key(
							 | 
						||
| 
								 | 
							
								                   &operation, PSA_KEY_DERIVATION_INPUT_SECRET,
							 | 
						||
| 
								 | 
							
								                   derived_key ) );
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_key_derivation_input_bytes(
							 | 
						||
| 
								 | 
							
								                   &operation, PSA_KEY_DERIVATION_INPUT_INFO,
							 | 
						||
| 
								 | 
							
								                   NULL, 0 ) );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Create the wrapping key. */
							 | 
						||
| 
								 | 
							
								    psa_set_key_usage_flags( &attributes, usage );
							 | 
						||
| 
								 | 
							
								    psa_set_key_algorithm( &attributes, WRAPPING_ALG );
							 | 
						||
| 
								 | 
							
								    psa_set_key_type( &attributes, PSA_KEY_TYPE_AES );
							 | 
						||
| 
								 | 
							
								    psa_set_key_bits( &attributes, WRAPPING_KEY_BITS );
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_key_derivation_output_key( &attributes, &operation,
							 | 
						||
| 
								 | 
							
								                                              wrapping_key ) );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								exit:
							 | 
						||
| 
								 | 
							
								    psa_key_derivation_abort( &operation );
							 | 
						||
| 
								 | 
							
								    return( status );
							 | 
						||
| 
								 | 
							
								}
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								static psa_status_t wrap_data( const char *input_file_name,
							 | 
						||
| 
								 | 
							
								                               const char *output_file_name,
							 | 
						||
| 
								 | 
							
								                               psa_key_id_t wrapping_key )
							 | 
						||
| 
								 | 
							
								{
							 | 
						||
| 
								 | 
							
								    psa_status_t status;
							 | 
						||
| 
								 | 
							
								    FILE *input_file = NULL;
							 | 
						||
| 
								 | 
							
								    FILE *output_file = NULL;
							 | 
						||
| 
								 | 
							
								    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
							 | 
						||
| 
								 | 
							
								    psa_key_type_t key_type;
							 | 
						||
| 
								 | 
							
								    long input_position;
							 | 
						||
| 
								 | 
							
								    size_t input_size;
							 | 
						||
| 
								 | 
							
								    size_t buffer_size = 0;
							 | 
						||
| 
								 | 
							
								    unsigned char *buffer = NULL;
							 | 
						||
| 
								 | 
							
								    size_t ciphertext_size;
							 | 
						||
| 
								 | 
							
								    wrapped_data_header_t header;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Find the size of the data to wrap. */
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( ( input_file = fopen( input_file_name, "rb" ) ) != NULL );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fseek( input_file, 0, SEEK_END ) == 0 );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( ( input_position = ftell( input_file ) ) != -1 );
							 | 
						||
| 
								 | 
							
								#if LONG_MAX > SIZE_MAX
							 | 
						||
| 
								 | 
							
								    if( input_position > SIZE_MAX )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "Input file too large.\n" );
							 | 
						||
| 
								 | 
							
								        status = DEMO_ERROR;
							 | 
						||
| 
								 | 
							
								        goto exit;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								#endif
							 | 
						||
| 
								 | 
							
								    input_size = input_position;
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_get_key_attributes( wrapping_key, &attributes ) );
							 | 
						||
| 
								 | 
							
								    key_type = psa_get_key_type( &attributes );
							 | 
						||
| 
								 | 
							
								    buffer_size =
							 | 
						||
| 
								 | 
							
								        PSA_AEAD_ENCRYPT_OUTPUT_SIZE( key_type, WRAPPING_ALG, input_size );
							 | 
						||
| 
								 | 
							
								    /* Check for integer overflow. */
							 | 
						||
| 
								 | 
							
								    if( buffer_size < input_size )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "Input file too large.\n" );
							 | 
						||
| 
								 | 
							
								        status = DEMO_ERROR;
							 | 
						||
| 
								 | 
							
								        goto exit;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Load the data to wrap. */
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fseek( input_file, 0, SEEK_SET ) == 0 );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( ( buffer = calloc( 1, buffer_size ) ) != NULL );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fread( buffer, 1, input_size, input_file ) == input_size );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fclose( input_file ) == 0 );
							 | 
						||
| 
								 | 
							
								    input_file = NULL;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Construct a header. */
							 | 
						||
| 
								 | 
							
								    memcpy( &header.magic, WRAPPED_DATA_MAGIC, WRAPPED_DATA_MAGIC_LENGTH );
							 | 
						||
| 
								 | 
							
								    header.ad_size = sizeof( header );
							 | 
						||
| 
								 | 
							
								    header.payload_size = input_size;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Wrap the data. */
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_generate_random( header.iv, WRAPPING_IV_SIZE ) );
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_aead_encrypt( wrapping_key, WRAPPING_ALG,
							 | 
						||
| 
								 | 
							
								                                 header.iv, WRAPPING_IV_SIZE,
							 | 
						||
| 
								 | 
							
								                                 (uint8_t *) &header, sizeof( header ),
							 | 
						||
| 
								 | 
							
								                                 buffer, input_size,
							 | 
						||
| 
								 | 
							
								                                 buffer, buffer_size,
							 | 
						||
| 
								 | 
							
								                                 &ciphertext_size ) );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Write the output. */
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( ( output_file = fopen( output_file_name, "wb" ) ) != NULL );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fwrite( &header, 1, sizeof( header ),
							 | 
						||
| 
								 | 
							
								                       output_file ) == sizeof( header ) );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fwrite( buffer, 1, ciphertext_size,
							 | 
						||
| 
								 | 
							
								                       output_file ) == ciphertext_size );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fclose( output_file ) == 0 );
							 | 
						||
| 
								 | 
							
								    output_file = NULL;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								exit:
							 | 
						||
| 
								 | 
							
								    if( input_file != NULL )
							 | 
						||
| 
								 | 
							
								        fclose( input_file );
							 | 
						||
| 
								 | 
							
								    if( output_file != NULL )
							 | 
						||
| 
								 | 
							
								        fclose( output_file );
							 | 
						||
| 
								 | 
							
								    if( buffer != NULL )
							 | 
						||
| 
								 | 
							
								        mbedtls_platform_zeroize( buffer, buffer_size );
							 | 
						||
| 
								 | 
							
								    free( buffer );
							 | 
						||
| 
								 | 
							
								    return( status );
							 | 
						||
| 
								 | 
							
								}
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								static psa_status_t unwrap_data( const char *input_file_name,
							 | 
						||
| 
								 | 
							
								                                 const char *output_file_name,
							 | 
						||
| 
								 | 
							
								                                 psa_key_id_t wrapping_key )
							 | 
						||
| 
								 | 
							
								{
							 | 
						||
| 
								 | 
							
								    psa_status_t status;
							 | 
						||
| 
								 | 
							
								    FILE *input_file = NULL;
							 | 
						||
| 
								 | 
							
								    FILE *output_file = NULL;
							 | 
						||
| 
								 | 
							
								    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
							 | 
						||
| 
								 | 
							
								    psa_key_type_t key_type;
							 | 
						||
| 
								 | 
							
								    unsigned char *buffer = NULL;
							 | 
						||
| 
								 | 
							
								    size_t ciphertext_size = 0;
							 | 
						||
| 
								 | 
							
								    size_t plaintext_size;
							 | 
						||
| 
								 | 
							
								    wrapped_data_header_t header;
							 | 
						||
| 
								 | 
							
								    unsigned char extra_byte;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Load and validate the header. */
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( ( input_file = fopen( input_file_name, "rb" ) ) != NULL );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fread( &header, 1, sizeof( header ),
							 | 
						||
| 
								 | 
							
								                      input_file ) == sizeof( header ) );
							 | 
						||
| 
								 | 
							
								    if( memcmp( &header.magic, WRAPPED_DATA_MAGIC,
							 | 
						||
| 
								 | 
							
								                WRAPPED_DATA_MAGIC_LENGTH ) != 0 )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "The input does not start with a valid magic header.\n" );
							 | 
						||
| 
								 | 
							
								        status = DEMO_ERROR;
							 | 
						||
| 
								 | 
							
								        goto exit;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								    if( header.ad_size != sizeof( header ) )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "The header size is not correct.\n" );
							 | 
						||
| 
								 | 
							
								        status = DEMO_ERROR;
							 | 
						||
| 
								 | 
							
								        goto exit;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_get_key_attributes( wrapping_key, &attributes) );
							 | 
						||
| 
								 | 
							
								    key_type = psa_get_key_type( &attributes);
							 | 
						||
| 
								 | 
							
								    ciphertext_size =
							 | 
						||
| 
								 | 
							
								        PSA_AEAD_ENCRYPT_OUTPUT_SIZE( key_type, WRAPPING_ALG, header.payload_size );
							 | 
						||
| 
								 | 
							
								    /* Check for integer overflow. */
							 | 
						||
| 
								 | 
							
								    if( ciphertext_size < header.payload_size )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "Input file too large.\n" );
							 | 
						||
| 
								 | 
							
								        status = DEMO_ERROR;
							 | 
						||
| 
								 | 
							
								        goto exit;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Load the payload data. */
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( ( buffer = calloc( 1, ciphertext_size ) ) != NULL );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fread( buffer, 1, ciphertext_size,
							 | 
						||
| 
								 | 
							
								                      input_file ) == ciphertext_size );
							 | 
						||
| 
								 | 
							
								    if( fread( &extra_byte, 1, 1, input_file ) != 0 )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "Extra garbage after ciphertext\n" );
							 | 
						||
| 
								 | 
							
								        status = DEMO_ERROR;
							 | 
						||
| 
								 | 
							
								        goto exit;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fclose( input_file ) == 0 );
							 | 
						||
| 
								 | 
							
								    input_file = NULL;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Unwrap the data. */
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_aead_decrypt( wrapping_key, WRAPPING_ALG,
							 | 
						||
| 
								 | 
							
								                                 header.iv, WRAPPING_IV_SIZE,
							 | 
						||
| 
								 | 
							
								                                 (uint8_t *) &header, sizeof( header ),
							 | 
						||
| 
								 | 
							
								                                 buffer, ciphertext_size,
							 | 
						||
| 
								 | 
							
								                                 buffer, ciphertext_size,
							 | 
						||
| 
								 | 
							
								                                 &plaintext_size ) );
							 | 
						||
| 
								 | 
							
								    if( plaintext_size != header.payload_size )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "Incorrect payload size in the header.\n" );
							 | 
						||
| 
								 | 
							
								        status = DEMO_ERROR;
							 | 
						||
| 
								 | 
							
								        goto exit;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Write the output. */
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( ( output_file = fopen( output_file_name, "wb" ) ) != NULL );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fwrite( buffer, 1, plaintext_size,
							 | 
						||
| 
								 | 
							
								                       output_file ) == plaintext_size );
							 | 
						||
| 
								 | 
							
								    SYS_CHECK( fclose( output_file ) == 0 );
							 | 
						||
| 
								 | 
							
								    output_file = NULL;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								exit:
							 | 
						||
| 
								 | 
							
								    if( input_file != NULL )
							 | 
						||
| 
								 | 
							
								        fclose( input_file );
							 | 
						||
| 
								 | 
							
								    if( output_file != NULL )
							 | 
						||
| 
								 | 
							
								        fclose( output_file );
							 | 
						||
| 
								 | 
							
								    if( buffer != NULL )
							 | 
						||
| 
								 | 
							
								        mbedtls_platform_zeroize( buffer, ciphertext_size );
							 | 
						||
| 
								 | 
							
								    free( buffer );
							 | 
						||
| 
								 | 
							
								    return( status );
							 | 
						||
| 
								 | 
							
								}
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								static psa_status_t run( enum program_mode mode,
							 | 
						||
| 
								 | 
							
								                         const char *key_file_name,
							 | 
						||
| 
								 | 
							
								                         const char *ladder[], size_t ladder_depth,
							 | 
						||
| 
								 | 
							
								                         const char *input_file_name,
							 | 
						||
| 
								 | 
							
								                         const char *output_file_name )
							 | 
						||
| 
								 | 
							
								{
							 | 
						||
| 
								 | 
							
								    psa_status_t status = PSA_SUCCESS;
							 | 
						||
| 
								 | 
							
								    psa_key_id_t derivation_key = 0;
							 | 
						||
| 
								 | 
							
								    psa_key_id_t wrapping_key = 0;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Initialize the PSA crypto library. */
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( psa_crypto_init( ) );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Generate mode is unlike the others. Generate the master key and exit. */
							 | 
						||
| 
								 | 
							
								    if( mode == MODE_GENERATE )
							 | 
						||
| 
								 | 
							
								        return( generate( key_file_name ) );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Read the master key. */
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( import_key_from_file( PSA_KEY_USAGE_DERIVE | PSA_KEY_USAGE_EXPORT,
							 | 
						||
| 
								 | 
							
								                                     KDF_ALG,
							 | 
						||
| 
								 | 
							
								                                     key_file_name,
							 | 
						||
| 
								 | 
							
								                                     &derivation_key ) );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    /* Calculate the derived key for this session. */
							 | 
						||
| 
								 | 
							
								    PSA_CHECK( derive_key_ladder( ladder, ladder_depth,
							 | 
						||
| 
								 | 
							
								                                  &derivation_key ) );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    switch( mode )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        case MODE_SAVE:
							 | 
						||
| 
								 | 
							
								            PSA_CHECK( save_key( derivation_key, output_file_name ) );
							 | 
						||
| 
								 | 
							
								            break;
							 | 
						||
| 
								 | 
							
								        case MODE_UNWRAP:
							 | 
						||
| 
								 | 
							
								            PSA_CHECK( derive_wrapping_key( PSA_KEY_USAGE_DECRYPT,
							 | 
						||
| 
								 | 
							
								                                            derivation_key,
							 | 
						||
| 
								 | 
							
								                                            &wrapping_key ) );
							 | 
						||
| 
								 | 
							
								            PSA_CHECK( unwrap_data( input_file_name, output_file_name,
							 | 
						||
| 
								 | 
							
								                                    wrapping_key ) );
							 | 
						||
| 
								 | 
							
								            break;
							 | 
						||
| 
								 | 
							
								        case MODE_WRAP:
							 | 
						||
| 
								 | 
							
								            PSA_CHECK( derive_wrapping_key( PSA_KEY_USAGE_ENCRYPT,
							 | 
						||
| 
								 | 
							
								                                            derivation_key,
							 | 
						||
| 
								 | 
							
								                                            &wrapping_key ) );
							 | 
						||
| 
								 | 
							
								            PSA_CHECK( wrap_data( input_file_name, output_file_name,
							 | 
						||
| 
								 | 
							
								                                  wrapping_key ) );
							 | 
						||
| 
								 | 
							
								            break;
							 | 
						||
| 
								 | 
							
								        default:
							 | 
						||
| 
								 | 
							
								            /* Unreachable but some compilers don't realize it. */
							 | 
						||
| 
								 | 
							
								            break;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								exit:
							 | 
						||
| 
								 | 
							
								    /* Destroy any remaining key. Deinitializing the crypto library would do
							 | 
						||
| 
								 | 
							
								     * this anyway since they are volatile keys, but explicitly destroying
							 | 
						||
| 
								 | 
							
								     * keys makes the code easier to reuse. */
							 | 
						||
| 
								 | 
							
								    (void) psa_destroy_key( derivation_key );
							 | 
						||
| 
								 | 
							
								    (void) psa_destroy_key( wrapping_key );
							 | 
						||
| 
								 | 
							
								    /* Deinitialize the PSA crypto library. */
							 | 
						||
| 
								 | 
							
								    mbedtls_psa_crypto_free( );
							 | 
						||
| 
								 | 
							
								    return( status );
							 | 
						||
| 
								 | 
							
								}
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								static void usage( void )
							 | 
						||
| 
								 | 
							
								{
							 | 
						||
| 
								 | 
							
								    printf( "Usage: key_ladder_demo MODE [OPTION=VALUE]...\n" );
							 | 
						||
| 
								 | 
							
								    printf( "Demonstrate the usage of a key derivation ladder.\n" );
							 | 
						||
| 
								 | 
							
								    printf( "\n" );
							 | 
						||
| 
								 | 
							
								    printf( "Modes:\n" );
							 | 
						||
| 
								 | 
							
								    printf( "  generate  Generate the master key\n" );
							 | 
						||
| 
								 | 
							
								    printf( "  save      Save the derived key\n" );
							 | 
						||
| 
								 | 
							
								    printf( "  unwrap    Unwrap (decrypt) input with the derived key\n" );
							 | 
						||
| 
								 | 
							
								    printf( "  wrap      Wrap (encrypt) input with the derived key\n" );
							 | 
						||
| 
								 | 
							
								    printf( "\n" );
							 | 
						||
| 
								 | 
							
								    printf( "Options:\n" );
							 | 
						||
| 
								 | 
							
								    printf( "  input=FILENAME    Input file (required for wrap/unwrap)\n" );
							 | 
						||
| 
								 | 
							
								    printf( "  master=FILENAME   File containing the master key (default: master.key)\n" );
							 | 
						||
| 
								 | 
							
								    printf( "  output=FILENAME   Output file (required for save/wrap/unwrap)\n" );
							 | 
						||
| 
								 | 
							
								    printf( "  label=TEXT        Label for the key derivation.\n" );
							 | 
						||
| 
								 | 
							
								    printf( "                    This may be repeated multiple times.\n" );
							 | 
						||
| 
								 | 
							
								    printf( "                    To get the same key, you must use the same master key\n" );
							 | 
						||
| 
								 | 
							
								    printf( "                    and the same sequence of labels.\n" );
							 | 
						||
| 
								 | 
							
								}
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								int main( int argc, char *argv[] )
							 | 
						||
| 
								 | 
							
								{
							 | 
						||
| 
								 | 
							
								    const char *key_file_name = "master.key";
							 | 
						||
| 
								 | 
							
								    const char *input_file_name = NULL;
							 | 
						||
| 
								 | 
							
								    const char *output_file_name = NULL;
							 | 
						||
| 
								 | 
							
								    const char *ladder[MAX_LADDER_DEPTH];
							 | 
						||
| 
								 | 
							
								    size_t ladder_depth = 0;
							 | 
						||
| 
								 | 
							
								    int i;
							 | 
						||
| 
								 | 
							
								    enum program_mode mode;
							 | 
						||
| 
								 | 
							
								    psa_status_t status;
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    if( argc <= 1 ||
							 | 
						||
| 
								 | 
							
								        strcmp( argv[1], "help" ) == 0 ||
							 | 
						||
| 
								 | 
							
								        strcmp( argv[1], "-help" ) == 0 ||
							 | 
						||
| 
								 | 
							
								        strcmp( argv[1], "--help" ) == 0 )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        usage( );
							 | 
						||
| 
								 | 
							
								        return( EXIT_SUCCESS );
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    for( i = 2; i < argc; i++ )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        char *q = strchr( argv[i], '=' );
							 | 
						||
| 
								 | 
							
								        if( q == NULL )
							 | 
						||
| 
								 | 
							
								        {
							 | 
						||
| 
								 | 
							
								            printf( "Missing argument to option %s\n", argv[i] );
							 | 
						||
| 
								 | 
							
								            goto usage_failure;
							 | 
						||
| 
								 | 
							
								        }
							 | 
						||
| 
								 | 
							
								        *q = 0;
							 | 
						||
| 
								 | 
							
								        ++q;
							 | 
						||
| 
								 | 
							
								        if( strcmp( argv[i], "input" ) == 0 )
							 | 
						||
| 
								 | 
							
								            input_file_name = q;
							 | 
						||
| 
								 | 
							
								        else if( strcmp( argv[i], "label" ) == 0 )
							 | 
						||
| 
								 | 
							
								        {
							 | 
						||
| 
								 | 
							
								            if( ladder_depth == MAX_LADDER_DEPTH )
							 | 
						||
| 
								 | 
							
								            {
							 | 
						||
| 
								 | 
							
								                printf( "Maximum ladder depth %u exceeded.\n",
							 | 
						||
| 
								 | 
							
								                                (unsigned) MAX_LADDER_DEPTH );
							 | 
						||
| 
								 | 
							
								                return( EXIT_FAILURE );
							 | 
						||
| 
								 | 
							
								            }
							 | 
						||
| 
								 | 
							
								            ladder[ladder_depth] = q;
							 | 
						||
| 
								 | 
							
								            ++ladder_depth;
							 | 
						||
| 
								 | 
							
								        }
							 | 
						||
| 
								 | 
							
								        else if( strcmp( argv[i], "master" ) == 0 )
							 | 
						||
| 
								 | 
							
								            key_file_name = q;
							 | 
						||
| 
								 | 
							
								        else if( strcmp( argv[i], "output" ) == 0 )
							 | 
						||
| 
								 | 
							
								            output_file_name = q;
							 | 
						||
| 
								 | 
							
								        else
							 | 
						||
| 
								 | 
							
								        {
							 | 
						||
| 
								 | 
							
								            printf( "Unknown option: %s\n", argv[i] );
							 | 
						||
| 
								 | 
							
								            goto usage_failure;
							 | 
						||
| 
								 | 
							
								        }
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    if( strcmp( argv[1], "generate" ) == 0 )
							 | 
						||
| 
								 | 
							
								        mode = MODE_GENERATE;
							 | 
						||
| 
								 | 
							
								    else if( strcmp( argv[1], "save" ) == 0 )
							 | 
						||
| 
								 | 
							
								        mode = MODE_SAVE;
							 | 
						||
| 
								 | 
							
								    else if( strcmp( argv[1], "unwrap" ) == 0 )
							 | 
						||
| 
								 | 
							
								        mode = MODE_UNWRAP;
							 | 
						||
| 
								 | 
							
								    else if( strcmp( argv[1], "wrap" ) == 0 )
							 | 
						||
| 
								 | 
							
								        mode = MODE_WRAP;
							 | 
						||
| 
								 | 
							
								    else
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "Unknown action: %s\n", argv[1] );
							 | 
						||
| 
								 | 
							
								        goto usage_failure;
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    if( input_file_name == NULL &&
							 | 
						||
| 
								 | 
							
								        ( mode == MODE_WRAP || mode == MODE_UNWRAP ) )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "Required argument missing: input\n" );
							 | 
						||
| 
								 | 
							
								        return( DEMO_ERROR );
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								    if( output_file_name == NULL &&
							 | 
						||
| 
								 | 
							
								        ( mode == MODE_SAVE || mode == MODE_WRAP || mode == MODE_UNWRAP ) )
							 | 
						||
| 
								 | 
							
								    {
							 | 
						||
| 
								 | 
							
								        printf( "Required argument missing: output\n" );
							 | 
						||
| 
								 | 
							
								        return( DEMO_ERROR );
							 | 
						||
| 
								 | 
							
								    }
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								    status = run( mode, key_file_name,
							 | 
						||
| 
								 | 
							
								                  ladder, ladder_depth,
							 | 
						||
| 
								 | 
							
								                  input_file_name, output_file_name );
							 | 
						||
| 
								 | 
							
								    return( status == PSA_SUCCESS ?
							 | 
						||
| 
								 | 
							
								            EXIT_SUCCESS :
							 | 
						||
| 
								 | 
							
								            EXIT_FAILURE );
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								usage_failure:
							 | 
						||
| 
								 | 
							
								    usage( );
							 | 
						||
| 
								 | 
							
								    return( EXIT_FAILURE );
							 | 
						||
| 
								 | 
							
								}
							 | 
						||
| 
								 | 
							
								#endif /* MBEDTLS_SHA256_C && MBEDTLS_MD_C && MBEDTLS_AES_C && MBEDTLS_CCM_C && MBEDTLS_PSA_CRYPTO_C && MBEDTLS_FS_IO */
							 |