/*
 * aes_calc.c
 *
 * A simple AES calculator for generating AES encryption values
 *
 * David A. McGrew
 * Cisco Systems, Inc.
 */

/*
 *
 * Copyright (c) 2001-2017, Cisco Systems, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 *   Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 *   Neither the name of the Cisco Systems, Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

/*

 Example usage (with first NIST FIPS 197 test case):

 [sh]$ test/aes_calc 000102030405060708090a0b0c0d0e0f \
       00112233445566778899aabbccddeeff -v

 plaintext:      00112233445566778899aabbccddeeff
 key:            000102030405060708090a0b0c0d0e0f
 ciphertext:     69c4e0d86a7b0430d8cdb78070b4c55a

 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "aes.h"
#include <stdio.h>
#include <string.h>
#include "util.h"

void usage(char *prog_name)
{
    printf("usage: %s <key> <plaintext> [<ciphertext>] [-v]\n", prog_name);
    exit(255);
}

#define AES_MAX_KEY_LEN 32

int main(int argc, char *argv[])
{
    const char *expected_ciphertext = NULL;
    const char *ciphertext = NULL;
    v128_t data;
    uint8_t key[AES_MAX_KEY_LEN];
    srtp_aes_expanded_key_t exp_key;
    int key_len, len;
    int verbose = 0;
    srtp_err_status_t status;

    /* -v must be last if it's passed */
    if (argc > 0 && strncmp(argv[argc - 1], "-v", 2) == 0) {
        /* we're in verbose mode */
        verbose = 1;
        --argc;
    }

    if (argc < 3 || argc > 4) {
        /* we've been fed the wrong number of arguments - compain and exit */
        usage(argv[0]);
    }

    if (argc == 4) {
        /* we're being passed the ciphertext to check (in unit test mode) */
        expected_ciphertext = argv[3];
        if (strlen(expected_ciphertext) != 16 * 2) {
            usage(argv[0]);
        }
    }

    /* read in key, checking length */
    if (strlen(argv[1]) > AES_MAX_KEY_LEN * 2) {
        fprintf(stderr, "error: too many digits in key "
                        "(should be at most %d hexadecimal digits, found %u)\n",
                AES_MAX_KEY_LEN * 2, (unsigned)strlen(argv[1]));
        exit(1);
    }
    len = hex_string_to_octet_string((char *)key, argv[1], AES_MAX_KEY_LEN * 2);
    /* check that hex string is the right length */
    if (len != 32 && len != 48 && len != 64) {
        fprintf(stderr, "error: bad number of digits in key "
                        "(should be 32/48/64 hexadecimal digits, found %d)\n",
                len);
        exit(1);
    }
    key_len = len / 2;

    /* read in plaintext, checking length */
    if (strlen(argv[2]) > 16 * 2) {
        fprintf(stderr, "error: too many digits in plaintext "
                        "(should be %d hexadecimal digits, found %u)\n",
                16 * 2, (unsigned)strlen(argv[2]));
        exit(1);
    }
    len = hex_string_to_octet_string((char *)(&data), argv[2], 16 * 2);
    /* check that hex string is the right length */
    if (len < 16 * 2) {
        fprintf(stderr, "error: too few digits in plaintext "
                        "(should be %d hexadecimal digits, found %d)\n",
                16 * 2, len);
        exit(1);
    }

    if (verbose) {
        /* print out plaintext */
        printf("plaintext:\t%s\n",
               octet_string_hex_string((uint8_t *)&data, 16));
    }

    /* encrypt plaintext */
    status = srtp_aes_expand_encryption_key(key, key_len, &exp_key);
    if (status) {
        fprintf(stderr, "error: AES key expansion failed.\n");
        exit(1);
    }

    srtp_aes_encrypt(&data, &exp_key);

    /* write ciphertext to output */
    if (verbose) {
        printf("key:\t\t%s\n", octet_string_hex_string(key, key_len));
        printf("ciphertext:\t");
    }

    ciphertext = v128_hex_string(&data);
    printf("%s\n", ciphertext);

    if (expected_ciphertext && strcmp(ciphertext, expected_ciphertext) != 0) {
        fprintf(stderr, "error: calculated ciphertext %s does not match "
                        "expected ciphertext %s\n",
                ciphertext, expected_ciphertext);
        exit(1);
    }

    return 0;
}
