/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_ML_NN_COMMON_TOKEN_HASHER_H
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#define ANDROID_ML_NN_COMMON_TOKEN_HASHER_H
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#include <cstring>
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#include <vector>
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#include <android-base/macros.h>
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#include <openssl/sha.h>
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namespace android {
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namespace nn {
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class TokenHasher {
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DISALLOW_COPY_AND_ASSIGN(TokenHasher);
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public:
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// Initializes the hasher with token. If token is nullptr, the hasher is set to be empty;
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// otherwise, it must be of length ANEURALNETWORKS_BYTE_SIZE_OF_CACHE_TOKEN.
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TokenHasher(const uint8_t* token);
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// Updates with a byte array. Returns false and sets to be empty on fail.
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// The client must check if the hasher is valid before invoking this method.
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bool update(const void* bytes, size_t length);
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// Updates with a string ended with '\0'. Returns false and sets to be empty on fail.
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// The client must check if the hasher is valid before invoking this method.
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bool updateFromString(const char* s) { return update(s, strlen(s)); }
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// Finishes the hasher, and writes re-hashed token to mToken.
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// Returns false and sets to be empty on fail.
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// The client must check if the hasher is valid before invoking this method.
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bool finish();
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// Returns a pointer to the transformed token if the hasher is successfully finished.
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// Returns nullptr if the hasher is initialized with a nullptr, or some call on the
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// hasher failed.
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// Aborts if the hasher is valid but finish has not been called.
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const uint8_t* getCacheToken() const;
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bool ok() const { return !mIsError; }
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private:
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// Stores the transformed token, non-empty iff the hasher is not initialized
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// with nullptr and finish is called.
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std::vector<uint8_t> mToken;
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SHA256_CTX mHasher;
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// Indicates that either the hasher is initialized with a nullptr, or some call on
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// the hasher failed.
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bool mIsError;
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};
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} // namespace nn
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} // namespace android
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#endif // ANDROID_ML_NN_COMMON_TOKEN_HASHER_H
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