/*
 * 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> [-v]\n", prog_name);
  exit(255);
}

#define AES_MAX_KEY_LEN 32

int
main (int argc, char *argv[]) {
  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;

  if (argc == 3) {
    /* we're not in verbose mode */
    verbose = 0;
  } else if (argc == 4) {
    if (strncmp(argv[3], "-v", 2) == 0) {
      /* we're in verbose mode */
      verbose = 1;
    } else {
      /* unrecognized flag, complain and exit */
      usage(argv[0]);
    }
  } else {
    /* we've been fed the wrong number of arguments - compain and exit */
    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");
  }
  printf("%s\n", v128_hex_string(&data));

  return 0;
}