1 // Copyright 2016 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/unguessable_token.h"
6
7 #include <ostream>
8 #include <string_view>
9
10 #include "base/check.h"
11 #include "base/format_macros.h"
12 #include "base/rand_util.h"
13 #include "build/build_config.h"
14
15 #if !BUILDFLAG(IS_NACL)
16 #include "third_party/boringssl/src/include/openssl/mem.h"
17 #endif
18
19 namespace base {
20
UnguessableToken(const base::Token & token)21 UnguessableToken::UnguessableToken(const base::Token& token) : token_(token) {}
22
23 // static
Create()24 UnguessableToken UnguessableToken::Create() {
25 Token token = Token::CreateRandom();
26 DCHECK(!token.is_zero());
27 return UnguessableToken(token);
28 }
29
30 // static
Null()31 const UnguessableToken& UnguessableToken::Null() {
32 static const UnguessableToken null_token{};
33 return null_token;
34 }
35
36 // static
Deserialize(uint64_t high,uint64_t low)37 std::optional<UnguessableToken> UnguessableToken::Deserialize(uint64_t high,
38 uint64_t low) {
39 // Receiving a zeroed out UnguessableToken from another process means that it
40 // was never initialized via Create(). Since this method might also be used to
41 // create an UnguessableToken from data on disk, we will handle this case more
42 // gracefully since data could have been corrupted.
43 if (high == 0 && low == 0) {
44 return std::nullopt;
45 }
46 return UnguessableToken(Token{high, low});
47 }
48
49 // static
DeserializeFromString(std::string_view string_representation)50 std::optional<UnguessableToken> UnguessableToken::DeserializeFromString(
51 std::string_view string_representation) {
52 auto token = Token::FromString(string_representation);
53 // A zeroed out token means that it's not initialized via Create().
54 if (!token.has_value() || token.value().is_zero()) {
55 return std::nullopt;
56 }
57 return UnguessableToken(token.value());
58 }
59
operator ==(const UnguessableToken & lhs,const UnguessableToken & rhs)60 bool operator==(const UnguessableToken& lhs, const UnguessableToken& rhs) {
61 #if BUILDFLAG(IS_NACL)
62 // BoringSSL is unavailable for NaCl builds so it remains timing dependent.
63 return lhs.token_ == rhs.token_;
64 #else
65 auto bytes = lhs.token_.AsBytes();
66 auto other_bytes = rhs.token_.AsBytes();
67 return CRYPTO_memcmp(bytes.data(), other_bytes.data(), bytes.size()) == 0;
68 #endif
69 }
70
operator <<(std::ostream & out,const UnguessableToken & token)71 std::ostream& operator<<(std::ostream& out, const UnguessableToken& token) {
72 return out << "(" << token.ToString() << ")";
73 }
74
75 } // namespace base
76