text: /*
   * cipher.c
   *
   * cipher meta-functions
   *
   * 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.
   *
   */
  
  #ifdef HAVE_CONFIG_H
  #include <config.h>
  #endif
  
  #include "cipher.h"
  #include "cipher_priv.h"
  #include "crypto_types.h"
  #include "err.h"   /* for srtp_debug */
  #include "alloc.h" /* for crypto_alloc(), crypto_free()  */
  
  srtp_debug_module_t srtp_mod_cipher = {
      0,       /* debugging is off by default */
      "cipher" /* printable module name       */
  };
  
  srtp_err_status_t srtp_cipher_type_alloc(const srtp_cipher_type_t *ct,
                                           srtp_cipher_t **c,
                                           int key_len,
                                           int tlen)
  {
      if (!ct || !ct->alloc) {
          return (srtp_err_status_bad_param);
      }
      return ((ct)->alloc((c), (key_len), (tlen)));
  }
  
  srtp_err_status_t srtp_cipher_dealloc(srtp_cipher_t *c)
  {
      if (!c || !c->type) {
          return (srtp_err_status_bad_param);
      }
      return (((c)->type)->dealloc(c));
  }
  
  srtp_err_status_t srtp_cipher_init(srtp_cipher_t *c, const uint8_t *key)
  {
      if (!c || !c->type || !c->state) {
          return (srtp_err_status_bad_param);
      }
      return (((c)->type)->init(((c)->state), (key)));
  }
  
  srtp_err_status_t srtp_cipher_set_iv(srtp_cipher_t *c,
                                       uint8_t *iv,
                                       int direction)
  {
      if (!c || !c->type || !c->state) {
          return (srtp_err_status_bad_param);
      }
  
      return (((c)->type)->set_iv(((c)->state), iv, direction));
  }
  
  srtp_err_status_t srtp_cipher_output(srtp_cipher_t *c,
                                       uint8_t *buffer,
                                       uint32_t *num_octets_to_output)
  {
      /* zeroize the buffer */
      octet_string_set_to_zero(buffer, *num_octets_to_output);
  
      /* exor keystream into buffer */
      return (((c)->type)->encrypt(((c)->state), buffer, num_octets_to_output));
  }
  
  srtp_err_status_t srtp_cipher_encrypt(srtp_cipher_t *c,
                                        uint8_t *buffer,
                                        uint32_t *num_octets_to_output)
  {
      if (!c || !c->type || !c->state) {
          return (srtp_err_status_bad_param);
      }
  
      return (((c)->type)->encrypt(((c)->state), buffer, num_octets_to_output));
  }
  
  srtp_err_status_t srtp_cipher_decrypt(srtp_cipher_t *c,
                                        uint8_t *buffer,
                                        uint32_t *num_octets_to_output)
  {
      if (!c || !c->type || !c->state) {
          return (srtp_err_status_bad_param);
      }
  
      return (((c)->type)->decrypt(((c)->state), buffer, num_octets_to_output));
  }
  
  srtp_err_status_t srtp_cipher_get_tag(srtp_cipher_t *c,
                                        uint8_t *buffer,
                                        uint32_t *tag_len)
  {
      if (!c || !c->type || !c->state) {
          return (srtp_err_status_bad_param);
      }
      if (!((c)->type)->get_tag) {
          return (srtp_err_status_no_such_op);
      }
  
      return (((c)->type)->get_tag(((c)->state), buffer, tag_len));
  }
  
  srtp_err_status_t srtp_cipher_set_aad(srtp_cipher_t *c,
                                        const uint8_t *aad,
                                        uint32_t aad_len)
  {
      if (!c || !c->type || !c->state) {
          return (srtp_err_status_bad_param);
      }
      if (!((c)->type)->set_aad) {
          return (srtp_err_status_no_such_op);
      }
  
      return (((c)->type)->set_aad(((c)->state), aad, aad_len));
  }
  
  /* some bookkeeping functions */
  
  int srtp_cipher_get_key_length(const srtp_cipher_t *c)
  {
      return c->key_len;
  }
  
  /*
   * A trivial platform independent random source.
   * For use in test only.
   */
  void srtp_cipher_rand_for_tests(void *dest, uint32_t len)
  {
      /* Generic C-library (rand()) version */
      /* This is a random source of last resort */
      uint8_t *dst = (uint8_t *)dest;
      while (len) {
          int val = rand();
          /* rand() returns 0-32767 (ugh) */
          /* Is this a good enough way to get random bytes?
             It is if it passes FIPS-140... */
          *dst++ = val & 0xff;
          len--;
      }
  }
  
  /*
   * A trivial platform independent 32 bit random number.
   * For use in test only.
   */
  uint32_t srtp_cipher_rand_u32_for_tests(void)
  {
      uint32_t r;
      srtp_cipher_rand_for_tests(&r, sizeof(r));
      return r;
  }
  
  #define SELF_TEST_BUF_OCTETS 128
  #define NUM_RAND_TESTS 128
  #define MAX_KEY_LEN 64
  /*
   * srtp_cipher_type_test(ct, test_data) tests a cipher of type ct against
   * test cases provided in a list test_data of values of key, salt, iv,
   * plaintext, and ciphertext that is known to be good
   */
  srtp_err_status_t srtp_cipher_type_test(
      const srtp_cipher_type_t *ct,
      const srtp_cipher_test_case_t *test_data)
  {
      const srtp_cipher_test_case_t *test_case = test_data;
      srtp_cipher_t *c;
      srtp_err_status_t status;
      uint8_t buffer[SELF_TEST_BUF_OCTETS];
      uint8_t buffer2[SELF_TEST_BUF_OCTETS];
      uint32_t tag_len;
      unsigned int len;
      int i, j, case_num = 0;
      unsigned k = 0;
  
      debug_print(srtp_mod_cipher, "running self-test for cipher %s",
                  ct->description);
  
      /*
       * check to make sure that we have at least one test case, and
       * return an error if we don't - we need to be paranoid here
       */
      if (test_case == NULL) {
          return srtp_err_status_cant_check;
      }
  
      /*
       * loop over all test cases, perform known-answer tests of both the
       * encryption and decryption functions
       */
      while (test_case != NULL) {
          /* allocate cipher */
          status = srtp_cipher_type_alloc(ct, &c, test_case->key_length_octets,
                                          test_case->tag_length_octets);
          if (status) {
              return status;
          }
  
          /*
           * test the encrypt function
           */
          debug_print(srtp_mod_cipher, "testing encryption", NULL);
  
          /* initialize cipher */
          status = srtp_cipher_init(c, test_case->key);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          /* copy plaintext into test buffer */
          if (test_case->ciphertext_length_octets > SELF_TEST_BUF_OCTETS) {
              srtp_cipher_dealloc(c);
              return srtp_err_status_bad_param;
          }
          for (k = 0; k < test_case->plaintext_length_octets; k++) {
              buffer[k] = test_case->plaintext[k];
          }
  
          debug_print(srtp_mod_cipher, "plaintext:    %s",
                      srtp_octet_string_hex_string(
                          buffer, test_case->plaintext_length_octets));
  
          /* set the initialization vector */
          status = srtp_cipher_set_iv(c, (uint8_t *)test_case->idx,
                                      srtp_direction_encrypt);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          if (c->algorithm == SRTP_AES_GCM_128 ||
              c->algorithm == SRTP_AES_GCM_256) {
              debug_print(srtp_mod_cipher, "IV:    %s",
                          srtp_octet_string_hex_string(test_case->idx, 12));
  
              /*
               * Set the AAD
               */
              status = srtp_cipher_set_aad(c, test_case->aad,
                                           test_case->aad_length_octets);
              if (status) {
                  srtp_cipher_dealloc(c);
                  return status;
              }
              debug_print(srtp_mod_cipher, "AAD:    %s",
                          srtp_octet_string_hex_string(
                              test_case->aad, test_case->aad_length_octets));
          }
  
          /* encrypt */
          len = test_case->plaintext_length_octets;
          status = srtp_cipher_encrypt(c, buffer, &len);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          if (c->algorithm == SRTP_AES_GCM_128 ||
              c->algorithm == SRTP_AES_GCM_256) {
              /*
               * Get the GCM tag
               */
              status = srtp_cipher_get_tag(c, buffer + len, &tag_len);
              if (status) {
                  srtp_cipher_dealloc(c);
                  return status;
              }
              len += tag_len;
          }
  
          debug_print(srtp_mod_cipher, "ciphertext:   %s",
                      srtp_octet_string_hex_string(
                          buffer, test_case->ciphertext_length_octets));
  
          /* compare the resulting ciphertext with that in the test case */
          if (len != test_case->ciphertext_length_octets) {
              srtp_cipher_dealloc(c);
              return srtp_err_status_algo_fail;
          }
          status = srtp_err_status_ok;
          for (k = 0; k < test_case->ciphertext_length_octets; k++) {
              if (buffer[k] != test_case->ciphertext[k]) {
                  status = srtp_err_status_algo_fail;
                  debug_print(srtp_mod_cipher, "test case %d failed", case_num);
                  debug_print(srtp_mod_cipher, "(failure at byte %u)", k);
                  break;
              }
          }
          if (status) {
              debug_print(srtp_mod_cipher, "c computed: %s",
                          srtp_octet_string_hex_string(
                              buffer, 2 * test_case->plaintext_length_octets));
              debug_print(srtp_mod_cipher, "c expected: %s",
                          srtp_octet_string_hex_string(
                              test_case->ciphertext,
                              2 * test_case->plaintext_length_octets));
  
              srtp_cipher_dealloc(c);
              return srtp_err_status_algo_fail;
          }
  
          /*
           * test the decrypt function
           */
          debug_print(srtp_mod_cipher, "testing decryption", NULL);
  
          /* re-initialize cipher for decryption */
          status = srtp_cipher_init(c, test_case->key);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          /* copy ciphertext into test buffer */
          if (test_case->ciphertext_length_octets > SELF_TEST_BUF_OCTETS) {
              srtp_cipher_dealloc(c);
              return srtp_err_status_bad_param;
          }
          for (k = 0; k < test_case->ciphertext_length_octets; k++) {
              buffer[k] = test_case->ciphertext[k];
          }
  
          debug_print(srtp_mod_cipher, "ciphertext:    %s",
                      srtp_octet_string_hex_string(
                          buffer, test_case->plaintext_length_octets));
  
          /* set the initialization vector */
          status = srtp_cipher_set_iv(c, (uint8_t *)test_case->idx,
                                      srtp_direction_decrypt);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          if (c->algorithm == SRTP_AES_GCM_128 ||
              c->algorithm == SRTP_AES_GCM_256) {
              /*
               * Set the AAD
               */
              status = srtp_cipher_set_aad(c, test_case->aad,
                                           test_case->aad_length_octets);
              if (status) {
                  srtp_cipher_dealloc(c);
                  return status;
              }
              debug_print(srtp_mod_cipher, "AAD:    %s",
                          srtp_octet_string_hex_string(
                              test_case->aad, test_case->aad_length_octets));
          }
  
          /* decrypt */
          len = test_case->ciphertext_length_octets;
          status = srtp_cipher_decrypt(c, buffer, &len);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          debug_print(srtp_mod_cipher, "plaintext:   %s",
                      srtp_octet_string_hex_string(
                          buffer, test_case->plaintext_length_octets));
  
          /* compare the resulting plaintext with that in the test case */
          if (len != test_case->plaintext_length_octets) {
              srtp_cipher_dealloc(c);
              return srtp_err_status_algo_fail;
          }
          status = srtp_err_status_ok;
          for (k = 0; k < test_case->plaintext_length_octets; k++) {
              if (buffer[k] != test_case->plaintext[k]) {
                  status = srtp_err_status_algo_fail;
                  debug_print(srtp_mod_cipher, "test case %d failed", case_num);
                  debug_print(srtp_mod_cipher, "(failure at byte %u)", k);
              }
          }
          if (status) {
              debug_print(srtp_mod_cipher, "p computed: %s",
                          srtp_octet_string_hex_string(
                              buffer, 2 * test_case->plaintext_length_octets));
              debug_print(srtp_mod_cipher, "p expected: %s",
                          srtp_octet_string_hex_string(
                              test_case->plaintext,
                              2 * test_case->plaintext_length_octets));
  
              srtp_cipher_dealloc(c);
              return srtp_err_status_algo_fail;
          }
  
          /* deallocate the cipher */
          status = srtp_cipher_dealloc(c);
          if (status) {
              return status;
          }
  
          /*
           * the cipher passed the test case, so move on to the next test
           * case in the list; if NULL, we'l proceed to the next test
           */
          test_case = test_case->next_test_case;
          ++case_num;
      }
  
      /* now run some random invertibility tests */
  
      /* allocate cipher, using paramaters from the first test case */
      test_case = test_data;
      status = srtp_cipher_type_alloc(ct, &c, test_case->key_length_octets,
                                      test_case->tag_length_octets);
      if (status) {
          return status;
      }
  
      for (j = 0; j < NUM_RAND_TESTS; j++) {
          unsigned int length;
          unsigned int plaintext_len;
          uint8_t key[MAX_KEY_LEN];
          uint8_t iv[MAX_KEY_LEN];
  
          /* choose a length at random (leaving room for IV and padding) */
          length = srtp_cipher_rand_u32_for_tests() % (SELF_TEST_BUF_OCTETS - 64);
          debug_print(srtp_mod_cipher, "random plaintext length %d\n", length);
          srtp_cipher_rand_for_tests(buffer, length);
  
          debug_print(srtp_mod_cipher, "plaintext:    %s",
                      srtp_octet_string_hex_string(buffer, length));
  
          /* copy plaintext into second buffer */
          for (i = 0; (unsigned int)i < length; i++) {
              buffer2[i] = buffer[i];
          }
  
          /* choose a key at random */
          if (test_case->key_length_octets > MAX_KEY_LEN) {
              srtp_cipher_dealloc(c);
              return srtp_err_status_cant_check;
          }
          srtp_cipher_rand_for_tests(key, test_case->key_length_octets);
  
          /* chose a random initialization vector */
          srtp_cipher_rand_for_tests(iv, MAX_KEY_LEN);
  
          /* initialize cipher */
          status = srtp_cipher_init(c, key);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          /* set initialization vector */
          status = srtp_cipher_set_iv(c, (uint8_t *)test_case->idx,
                                      srtp_direction_encrypt);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          if (c->algorithm == SRTP_AES_GCM_128 ||
              c->algorithm == SRTP_AES_GCM_256) {
              /*
               * Set the AAD
               */
              status = srtp_cipher_set_aad(c, test_case->aad,
                                           test_case->aad_length_octets);
              if (status) {
                  srtp_cipher_dealloc(c);
                  return status;
              }
              debug_print(srtp_mod_cipher, "AAD:    %s",
                          srtp_octet_string_hex_string(
                              test_case->aad, test_case->aad_length_octets));
          }
  
          /* encrypt buffer with cipher */
          plaintext_len = length;
          status = srtp_cipher_encrypt(c, buffer, &length);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
          if (c->algorithm == SRTP_AES_GCM_128 ||
              c->algorithm == SRTP_AES_GCM_256) {
              /*
               * Get the GCM tag
               */
              status = srtp_cipher_get_tag(c, buffer + length, &tag_len);
              if (status) {
                  srtp_cipher_dealloc(c);
                  return status;
              }
              length += tag_len;
          }
          debug_print(srtp_mod_cipher, "ciphertext:   %s",
                      srtp_octet_string_hex_string(buffer, length));
  
          /*
           * re-initialize cipher for decryption, re-set the iv, then
           * decrypt the ciphertext
           */
          status = srtp_cipher_init(c, key);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
          status = srtp_cipher_set_iv(c, (uint8_t *)test_case->idx,
                                      srtp_direction_decrypt);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
          if (c->algorithm == SRTP_AES_GCM_128 ||
              c->algorithm == SRTP_AES_GCM_256) {
              /*
               * Set the AAD
               */
              status = srtp_cipher_set_aad(c, test_case->aad,
                                           test_case->aad_length_octets);
              if (status) {
                  srtp_cipher_dealloc(c);
                  return status;
              }
              debug_print(srtp_mod_cipher, "AAD:    %s",
                          srtp_octet_string_hex_string(
                              test_case->aad, test_case->aad_length_octets));
          }
          status = srtp_cipher_decrypt(c, buffer, &length);
          if (status) {
              srtp_cipher_dealloc(c);
              return status;
          }
  
          debug_print(srtp_mod_cipher, "plaintext[2]: %s",
                      srtp_octet_string_hex_string(buffer, length));
  
          /* compare the resulting plaintext with the original one */
          if (length != plaintext_len) {
              srtp_cipher_dealloc(c);
              return srtp_err_status_algo_fail;
          }
          status = srtp_err_status_ok;
          for (k = 0; k < plaintext_len; k++) {
              if (buffer[k] != buffer2[k]) {
                  status = srtp_err_status_algo_fail;
                  debug_print(srtp_mod_cipher, "random test case %d failed",
                              case_num);
                  debug_print(srtp_mod_cipher, "(failure at byte %u)", k);
              }
          }
          if (status) {
              srtp_cipher_dealloc(c);
              return srtp_err_status_algo_fail;
          }
      }
  
      status = srtp_cipher_dealloc(c);
      if (status) {
          return status;
      }
  
      return srtp_err_status_ok;
  }
  
  /*
   * srtp_cipher_type_self_test(ct) performs srtp_cipher_type_test on ct's
   * internal list of test data.
   */
  srtp_err_status_t srtp_cipher_type_self_test(const srtp_cipher_type_t *ct)
  {
      return srtp_cipher_type_test(ct, ct->test_data);
  }
  
  /*
   * cipher_bits_per_second(c, l, t) computes (an estimate of) the
   * number of bits that a cipher implementation can encrypt in a second
   *
   * c is a cipher (which MUST be allocated and initialized already), l
   * is the length in octets of the test data to be encrypted, and t is
   * the number of trials
   *
   * if an error is encountered, the value 0 is returned
   */
  uint64_t srtp_cipher_bits_per_second(srtp_cipher_t *c,
                                       int octets_in_buffer,
                                       int num_trials)
  {
      int i;
      v128_t nonce;
      clock_t timer;
      unsigned char *enc_buf;
      unsigned int len = octets_in_buffer;
  
      enc_buf = (unsigned char *)srtp_crypto_alloc(octets_in_buffer);
      if (enc_buf == NULL) {
          return 0; /* indicate bad parameters by returning null */
      }
      /* time repeated trials */
      v128_set_to_zero(&nonce);
      timer = clock();
      for (i = 0; i < num_trials; i++, nonce.v32[3] = i) {
          if (srtp_cipher_set_iv(c, (uint8_t *)&nonce, srtp_direction_encrypt) !=
              srtp_err_status_ok) {
              srtp_crypto_free(enc_buf);
              return 0;
          }
          if (srtp_cipher_encrypt(c, enc_buf, &len) != srtp_err_status_ok) {
              srtp_crypto_free(enc_buf);
              return 0;
          }
      }
      timer = clock() - timer;
  
      srtp_crypto_free(enc_buf);
  
      if (timer == 0) {
          /* Too fast! */
          return 0;
      }
  
      return (uint64_t)CLOCKS_PER_SEC * num_trials * 8 * octets_in_buffer / timer;
  }
  