| /* |
| * 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_ISO18033KDF_H_ |
| #define SYSTEM_KEYMASTER_ISO18033KDF_H_ |
| |
| #include "kdf.h" |
| |
| #include <hardware/keymaster_defs.h> |
| |
| #include <keymaster/serializable.h> |
| |
| #include <keymaster/UniquePtr.h> |
| |
| namespace keymaster { |
| |
| /** |
| * A light implementation of ISO18033KDF as defined by ISO-18033-2 (www.shoup.net/iso/std6.pdf) and |
| * its slightly different variant ANSI-X9-42. |
| */ |
| class Iso18033Kdf : public Kdf { |
| public: |
| ~Iso18033Kdf() {} |
| |
| bool Init(keymaster_digest_t digest_type, const uint8_t* secret, size_t secret_len) { |
| return Kdf::Init(digest_type, secret, secret_len, nullptr /* salt */, 0 /* salt_len */); |
| } |
| |
| /** |
| * Generates ISO18033's derived key, as defined in ISO-18033-2 and ANSI-X9-42. In ISO 18033-2, |
| * KDF takes a secret and outputs: |
| * |
| * hash(secret || start_counter) || hash(secret|| start_counter + 1) || ... |
| * |
| * In ANSI-X9-42, KDF takes a secret and additional info, and outputs: |
| * |
| * hash(secret || start_counter || info) || hash(secret || start_counter + 1 || info) || ... |
| * |
| * Note that the KDFs are the same if the info field is considered optional. In both cases the |
| * length of the output is specified by the caller, and the counter is encoded as a 4-element |
| * byte array. |
| */ |
| bool GenerateKey(const uint8_t* info, size_t info_len, uint8_t* output, |
| size_t output_len) override; |
| |
| protected: |
| explicit Iso18033Kdf(uint32_t start_counter) : start_counter_(start_counter) {} |
| |
| private: |
| uint32_t start_counter_; |
| }; |
| |
| } // namespace keymaster |
| |
| #endif // SYSTEM_KEYMASTER_ISO18033KDF_H_ |