tguilbert | 76e690d | 2016-09-20 06:11:25 +0900 | [diff] [blame] | 1 | // Copyright 2016 The Chromium Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef BASE_UNGUESSABLE_TOKEN_H_ |
| 6 | #define BASE_UNGUESSABLE_TOKEN_H_ |
| 7 | |
| 8 | #include <stdint.h> |
| 9 | #include <string.h> |
tguilbert | 84d2d03 | 2016-09-20 11:04:50 +0900 | [diff] [blame] | 10 | #include <iosfwd> |
tguilbert | 76e690d | 2016-09-20 06:11:25 +0900 | [diff] [blame] | 11 | #include <tuple> |
| 12 | |
| 13 | #include "base/base_export.h" |
| 14 | #include "base/hash.h" |
| 15 | #include "base/logging.h" |
| 16 | |
| 17 | namespace base { |
| 18 | |
| 19 | struct UnguessableTokenHash; |
| 20 | |
| 21 | // A UnguessableToken is an 128-bit token generated from a cryptographically |
| 22 | // strong random source. |
| 23 | // |
| 24 | // UnguessableToken should be used when a sensitive ID needs to be unguessable, |
| 25 | // and is shared across processes. It can be used as part of a larger aggregate |
| 26 | // type, or as an ID in and of itself. |
| 27 | // |
| 28 | // Use Create() for creating new UnguessableTokens. |
| 29 | // |
| 30 | // NOTE: It is illegal to send empty UnguessableTokens across processes, and |
| 31 | // sending/receiving empty tokens should be treated as a security issue. |
| 32 | // If there is a valid scenario for sending "no token" across processes, |
| 33 | // base::Optional should be used instead of an empty token. |
| 34 | class BASE_EXPORT UnguessableToken { |
| 35 | public: |
| 36 | // Create a unique UnguessableToken. |
| 37 | static UnguessableToken Create(); |
| 38 | |
| 39 | // Return a UnguessableToken built from the high/low bytes provided. |
| 40 | // It should only be used in deserialization scenarios. |
| 41 | // |
| 42 | // NOTE: If the deserialized token is empty, it means that it was never |
| 43 | // initialized via Create(). This is a security issue, and should be handled. |
| 44 | static UnguessableToken Deserialize(uint64_t high, uint64_t low); |
| 45 | |
| 46 | // Creates an empty UnguessableToken. |
| 47 | // Assign to it with Create() before using it. |
staraz | 905dffe | 2016-11-11 09:19:17 +0900 | [diff] [blame] | 48 | constexpr UnguessableToken() = default; |
tguilbert | 76e690d | 2016-09-20 06:11:25 +0900 | [diff] [blame] | 49 | |
| 50 | // NOTE: Serializing an empty UnguessableToken is an illegal operation. |
| 51 | uint64_t GetHighForSerialization() const { |
| 52 | DCHECK(!is_empty()); |
| 53 | return high_; |
yucliu | 1d06b83 | 2017-08-01 15:06:30 +0900 | [diff] [blame] | 54 | } |
tguilbert | 76e690d | 2016-09-20 06:11:25 +0900 | [diff] [blame] | 55 | |
| 56 | // NOTE: Serializing an empty UnguessableToken is an illegal operation. |
| 57 | uint64_t GetLowForSerialization() const { |
| 58 | DCHECK(!is_empty()); |
| 59 | return low_; |
| 60 | } |
| 61 | |
| 62 | bool is_empty() const { return high_ == 0 && low_ == 0; } |
| 63 | |
| 64 | std::string ToString() const; |
| 65 | |
| 66 | explicit operator bool() const { return !is_empty(); } |
| 67 | |
| 68 | bool operator<(const UnguessableToken& other) const { |
| 69 | return std::tie(high_, low_) < std::tie(other.high_, other.low_); |
| 70 | } |
| 71 | |
| 72 | bool operator==(const UnguessableToken& other) const { |
| 73 | return high_ == other.high_ && low_ == other.low_; |
| 74 | } |
| 75 | |
| 76 | bool operator!=(const UnguessableToken& other) const { |
| 77 | return !(*this == other); |
| 78 | } |
| 79 | |
| 80 | private: |
| 81 | friend struct UnguessableTokenHash; |
| 82 | UnguessableToken(uint64_t high, uint64_t low); |
| 83 | |
| 84 | // Note: Two uint64_t are used instead of uint8_t[16], in order to have a |
| 85 | // simpler ToString() and is_empty(). |
| 86 | uint64_t high_ = 0; |
| 87 | uint64_t low_ = 0; |
| 88 | }; |
| 89 | |
tguilbert | 84d2d03 | 2016-09-20 11:04:50 +0900 | [diff] [blame] | 90 | BASE_EXPORT std::ostream& operator<<(std::ostream& out, |
| 91 | const UnguessableToken& token); |
| 92 | |
tguilbert | 76e690d | 2016-09-20 06:11:25 +0900 | [diff] [blame] | 93 | // For use in std::unordered_map. |
| 94 | struct UnguessableTokenHash { |
| 95 | size_t operator()(const base::UnguessableToken& token) const { |
| 96 | DCHECK(token); |
| 97 | return base::HashInts64(token.high_, token.low_); |
| 98 | } |
| 99 | }; |
| 100 | |
| 101 | } // namespace base |
| 102 | |
| 103 | #endif // BASE_UNGUESSABLE_TOKEN_H_ |