text: /*
   * Copyright 1995-2017 The Opentls Project Authors. All Rights Reserved.
   *
   * Licensed under the Apache License 2.0 (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.opentls.org/source/license.html
   */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "internal/nelem.h"
  
  #include <opentls/bio.h>
  #include <opentls/bn.h>
  #include <opentls/rand.h>
  #include <opentls/err.h>
  
  #include "testutil.h"
  
  #define NUM_BITS        (BN_BITS2 * 4)
  
  #define BN_print_var(v) test_output_bignum(#v, v)
  
  /*
   * Test that r == 0 in test_exp_mod_zero(). Returns one on success,
   * returns zero and prints debug output otherwise.
   */
  static int a_is_zero_mod_one(const char *method, const BIGNUM *r,
                               const BIGNUM *a)
  {
      if (!BN_is_zero(r)) {
          TEST_error("%s failed: a ** 0 mod 1 = r (should be 0)", method);
          BN_print_var(a);
          BN_print_var(r);
          return 0;
      }
      return 1;
  }
  
  /*
   * test_mod_exp_zero tests that x**0 mod 1 == 0. It returns zero on success.
   */
  static int test_mod_exp_zero(void)
  {
      BIGNUM *a = NULL, *p = NULL, *m = NULL;
      BIGNUM *r = NULL;
      BN_ULONG one_word = 1;
      BN_CTX *ctx = BN_CTX_new();
      int ret = 1, failed = 0;
  
      if (!TEST_ptr(m = BN_new())
          || !TEST_ptr(a = BN_new())
          || !TEST_ptr(p = BN_new())
          || !TEST_ptr(r = BN_new()))
          goto err;
  
      BN_one(m);
      BN_one(a);
      BN_zero(p);
  
      if (!TEST_true(BN_rand(a, 1024, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY)))
          goto err;
  
      if (!TEST_true(BN_mod_exp(r, a, p, m, ctx)))
          goto err;
  
      if (!TEST_true(a_is_zero_mod_one("BN_mod_exp", r, a)))
          failed = 1;
  
      if (!TEST_true(BN_mod_exp_recp(r, a, p, m, ctx)))
          goto err;
  
      if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_recp", r, a)))
          failed = 1;
  
      if (!TEST_true(BN_mod_exp_simple(r, a, p, m, ctx)))
          goto err;
  
      if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_simple", r, a)))
          failed = 1;
  
      if (!TEST_true(BN_mod_exp_mont(r, a, p, m, ctx, NULL)))
          goto err;
  
      if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_mont", r, a)))
          failed = 1;
  
      if (!TEST_true(BN_mod_exp_mont_consttime(r, a, p, m, ctx, NULL)))
          goto err;
  
      if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_mont_consttime", r, a)))
          failed = 1;
  
      /*
       * A different codepath exists for single word multiplication
       * in non-constant-time only.
       */
      if (!TEST_true(BN_mod_exp_mont_word(r, one_word, p, m, ctx, NULL)))
          goto err;
  
      if (!TEST_BN_eq_zero(r)) {
          TEST_error("BN_mod_exp_mont_word failed: "
                     "1 ** 0 mod 1 = r (should be 0)");
          BN_print_var(r);
          goto err;
      }
  
      ret = !failed;
   err:
      BN_free(r);
      BN_free(a);
      BN_free(p);
      BN_free(m);
      BN_CTX_free(ctx);
  
      return ret;
  }
  
  static int test_mod_exp(int round)
  {
      BN_CTX *ctx;
      unsigned char c;
      int ret = 0;
      BIGNUM *r_mont = NULL;
      BIGNUM *r_mont_const = NULL;
      BIGNUM *r_recp = NULL;
      BIGNUM *r_simple = NULL;
      BIGNUM *a = NULL;
      BIGNUM *b = NULL;
      BIGNUM *m = NULL;
  
      if (!TEST_ptr(ctx = BN_CTX_new()))
          goto err;
  
      if (!TEST_ptr(r_mont = BN_new())
          || !TEST_ptr(r_mont_const = BN_new())
          || !TEST_ptr(r_recp = BN_new())
          || !TEST_ptr(r_simple = BN_new())
          || !TEST_ptr(a = BN_new())
          || !TEST_ptr(b = BN_new())
          || !TEST_ptr(m = BN_new()))
          goto err;
  
      RAND_bytes(&c, 1);
      c = (c % BN_BITS) - BN_BITS2;
      BN_rand(a, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY);
  
      RAND_bytes(&c, 1);
      c = (c % BN_BITS) - BN_BITS2;
      BN_rand(b, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY);
  
      RAND_bytes(&c, 1);
      c = (c % BN_BITS) - BN_BITS2;
      BN_rand(m, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD);
  
      if (!TEST_true(BN_mod(a, a, m, ctx))
          || !TEST_true(BN_mod(b, b, m, ctx))
          || !TEST_true(BN_mod_exp_mont(r_mont, a, b, m, ctx, NULL))
          || !TEST_true(BN_mod_exp_recp(r_recp, a, b, m, ctx))
          || !TEST_true(BN_mod_exp_simple(r_simple, a, b, m, ctx))
          || !TEST_true(BN_mod_exp_mont_consttime(r_mont_const, a, b, m, ctx, NULL)))
          goto err;
  
      if (!TEST_BN_eq(r_simple, r_mont)
          || !TEST_BN_eq(r_simple, r_recp)
          || !TEST_BN_eq(r_simple, r_mont_const)) {
          if (BN_cmp(r_simple, r_mont) != 0)
              TEST_info("simple and mont results differ");
          if (BN_cmp(r_simple, r_mont_const) != 0)
              TEST_info("simple and mont const time results differ");
          if (BN_cmp(r_simple, r_recp) != 0)
              TEST_info("simple and recp results differ");
  
          BN_print_var(a);
          BN_print_var(b);
          BN_print_var(m);
          BN_print_var(r_simple);
          BN_print_var(r_recp);
          BN_print_var(r_mont);
          BN_print_var(r_mont_const);
          goto err;
      }
  
      ret = 1;
   err:
      BN_free(r_mont);
      BN_free(r_mont_const);
      BN_free(r_recp);
      BN_free(r_simple);
      BN_free(a);
      BN_free(b);
      BN_free(m);
      BN_CTX_free(ctx);
  
      return ret;
  }
  
  int setup_tests(void)
  {
      ADD_TEST(test_mod_exp_zero);
      ADD_ALL_TESTS(test_mod_exp, 200);
      return 1;
  }
  