Thai Duong | 7689ed6 | 2015-03-20 16:50:18 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2015 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef SYSTEM_KEYMASTER_HMAC_H_ |
| 18 | #define SYSTEM_KEYMASTER_HMAC_H_ |
| 19 | |
| 20 | #include <keymaster/serializable.h> |
| 21 | |
| 22 | namespace keymaster { |
| 23 | |
Thai Duong | 7689ed6 | 2015-03-20 16:50:18 -0700 | [diff] [blame] | 24 | // Only HMAC-SHA256 is supported. |
| 25 | class HmacSha256 { |
| 26 | public: |
Thai Duong | 60eebdc | 2015-03-25 17:20:24 -0700 | [diff] [blame] | 27 | HmacSha256(){}; |
Thai Duong | 7689ed6 | 2015-03-20 16:50:18 -0700 | [diff] [blame] | 28 | |
| 29 | // DigestLength returns the length, in bytes, of the resulting digest. |
| 30 | size_t DigestLength() const; |
| 31 | |
| 32 | // Initializes this instance using |key|. Call Init only once. It returns |
| 33 | // false on the second of later calls. |
| 34 | bool Init(const uint8_t* key, size_t key_length); |
| 35 | bool Init(const Buffer& key); |
| 36 | |
| 37 | // Sign calculates the HMAC of |data| with the key supplied to the Init |
| 38 | // method. At most |digest_len| bytes of the resulting digest are written |
| 39 | // to |digest|. |
| 40 | bool Sign(const Buffer& data, uint8_t* digest, size_t digest_len) const; |
| 41 | bool Sign(const uint8_t* data, size_t data_len, uint8_t* digest, size_t digest_len) const; |
| 42 | |
| 43 | // Verify returns true if |digest| is a valid HMAC of |data| using the key |
| 44 | // supplied to Init. |digest| must be exactly |DigestLength()| bytes long. |
| 45 | // Use of this method is strongly recommended over using Sign() with a manual |
| 46 | // comparison (such as memcmp), as such comparisons may result in |
| 47 | // side-channel disclosures, such as timing, that undermine the cryptographic |
| 48 | // integrity. |
| 49 | bool Verify(const Buffer& data, const Buffer& digest) const; |
| 50 | bool Verify(const uint8_t* data, size_t data_len, const uint8_t* digest, |
| 51 | size_t digest_len) const; |
| 52 | |
| 53 | private: |
Thai Duong | 60eebdc | 2015-03-25 17:20:24 -0700 | [diff] [blame] | 54 | UniquePtr<uint8_t[]> key_; |
| 55 | size_t key_len_; |
Thai Duong | 7689ed6 | 2015-03-20 16:50:18 -0700 | [diff] [blame] | 56 | }; |
| 57 | |
| 58 | } // namespace keymaster |
| 59 | |
| 60 | #endif // SYSTEM_KEYMASTER_HMAC_H_ |