upload android base code part6

android/system/keymaster/hmac.h

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+/*
+ * 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_