1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "absl/random/seed_sequences.h"
16
17 #include <iterator>
18 #include <random>
19
20 #include "gmock/gmock.h"
21 #include "gtest/gtest.h"
22 #include "absl/random/internal/nonsecure_base.h"
23 #include "absl/random/random.h"
24 namespace {
25
TEST(SeedSequences,Examples)26 TEST(SeedSequences, Examples) {
27 {
28 absl::SeedSeq seed_seq({1, 2, 3});
29 absl::BitGen bitgen(seed_seq);
30
31 EXPECT_NE(0, bitgen());
32 }
33 {
34 absl::BitGen engine;
35 auto seed_seq = absl::CreateSeedSeqFrom(&engine);
36 absl::BitGen bitgen(seed_seq);
37
38 EXPECT_NE(engine(), bitgen());
39 }
40 {
41 auto seed_seq = absl::MakeSeedSeq();
42 std::mt19937 random(seed_seq);
43
44 EXPECT_NE(0, random());
45 }
46 }
47
TEST(CreateSeedSeqFrom,CompatibleWithStdTypes)48 TEST(CreateSeedSeqFrom, CompatibleWithStdTypes) {
49 using ExampleNonsecureURBG =
50 absl::random_internal::NonsecureURBGBase<std::minstd_rand0>;
51
52 // Construct a URBG instance.
53 ExampleNonsecureURBG rng;
54
55 // Construct a Seed Sequence from its variates.
56 auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
57
58 // Ensure that another URBG can be validly constructed from the Seed Sequence.
59 std::mt19937_64{seq_from_rng};
60 }
61
TEST(CreateSeedSeqFrom,CompatibleWithBitGenerator)62 TEST(CreateSeedSeqFrom, CompatibleWithBitGenerator) {
63 // Construct a URBG instance.
64 absl::BitGen rng;
65
66 // Construct a Seed Sequence from its variates.
67 auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
68
69 // Ensure that another URBG can be validly constructed from the Seed Sequence.
70 std::mt19937_64{seq_from_rng};
71 }
72
TEST(CreateSeedSeqFrom,CompatibleWithInsecureBitGen)73 TEST(CreateSeedSeqFrom, CompatibleWithInsecureBitGen) {
74 // Construct a URBG instance.
75 absl::InsecureBitGen rng;
76
77 // Construct a Seed Sequence from its variates.
78 auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
79
80 // Ensure that another URBG can be validly constructed from the Seed Sequence.
81 std::mt19937_64{seq_from_rng};
82 }
83
TEST(CreateSeedSeqFrom,CompatibleWithRawURBG)84 TEST(CreateSeedSeqFrom, CompatibleWithRawURBG) {
85 // Construct a URBG instance.
86 std::random_device urandom;
87
88 // Construct a Seed Sequence from its variates, using 64b of seed-material.
89 auto seq_from_rng = absl::CreateSeedSeqFrom(&urandom);
90
91 // Ensure that another URBG can be validly constructed from the Seed Sequence.
92 std::mt19937_64{seq_from_rng};
93 }
94
95 template <typename URBG>
TestReproducibleVariateSequencesForNonsecureURBG()96 void TestReproducibleVariateSequencesForNonsecureURBG() {
97 const size_t kNumVariates = 1000;
98
99 // Master RNG instance.
100 URBG rng;
101 // Reused for both RNG instances.
102 auto reusable_seed = absl::CreateSeedSeqFrom(&rng);
103
104 typename URBG::result_type variates[kNumVariates];
105 {
106 URBG child(reusable_seed);
107 for (auto& variate : variates) {
108 variate = child();
109 }
110 }
111 // Ensure that variate-sequence can be "replayed" by identical RNG.
112 {
113 URBG child(reusable_seed);
114 for (auto& variate : variates) {
115 ASSERT_EQ(variate, child());
116 }
117 }
118 }
119
TEST(CreateSeedSeqFrom,ReproducesVariateSequencesForInsecureBitGen)120 TEST(CreateSeedSeqFrom, ReproducesVariateSequencesForInsecureBitGen) {
121 TestReproducibleVariateSequencesForNonsecureURBG<absl::InsecureBitGen>();
122 }
123
TEST(CreateSeedSeqFrom,ReproducesVariateSequencesForBitGenerator)124 TEST(CreateSeedSeqFrom, ReproducesVariateSequencesForBitGenerator) {
125 TestReproducibleVariateSequencesForNonsecureURBG<absl::BitGen>();
126 }
127 } // namespace
128