| /* |
| * Copyright 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef SYSTEM_KEYMASTER_HMAC_H_ |
| #define SYSTEM_KEYMASTER_HMAC_H_ |
| |
| #include <keymaster/serializable.h> |
| |
| namespace keymaster { |
| |
| // Only HMAC-SHA256 is supported. |
| class HmacSha256 { |
| public: |
| HmacSha256(){}; |
| |
| // DigestLength returns the length, in bytes, of the resulting digest. |
| size_t DigestLength() const; |
| |
| // Initializes this instance using |key|. Call Init only once. It returns |
| // false on the second of later calls. |
| bool Init(const uint8_t* key, size_t key_length); |
| bool Init(const Buffer& key); |
| |
| // Sign calculates the HMAC of |data| with the key supplied to the Init |
| // method. At most |digest_len| bytes of the resulting digest are written |
| // to |digest|. |
| bool Sign(const Buffer& data, uint8_t* digest, size_t digest_len) const; |
| bool Sign(const uint8_t* data, size_t data_len, uint8_t* digest, size_t digest_len) const; |
| |
| // Verify returns true if |digest| is a valid HMAC of |data| using the key |
| // supplied to Init. |digest| must be exactly |DigestLength()| bytes long. |
| // Use of this method is strongly recommended over using Sign() with a manual |
| // comparison (such as memcmp), as such comparisons may result in |
| // side-channel disclosures, such as timing, that undermine the cryptographic |
| // integrity. |
| bool Verify(const Buffer& data, const Buffer& digest) const; |
| bool Verify(const uint8_t* data, size_t data_len, const uint8_t* digest, |
| size_t digest_len) const; |
| |
| private: |
| UniquePtr<uint8_t[]> key_; |
| size_t key_len_; |
| }; |
| |
| } // namespace keymaster |
| |
| #endif // SYSTEM_KEYMASTER_HMAC_H_ |