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hai007
05ae5583f8
them with chromium ::crypto symbols of the same names. PiperOrigin-RevId: 684566882
111 lines
4.0 KiB
C++
111 lines
4.0 KiB
C++
// Copyright 2020 Google LLC
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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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// https://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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#ifndef THIRD_PARTY_NEARBY_INTERNAL_CRYPTO_ENCRYPTOR_H_
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#define THIRD_PARTY_NEARBY_INTERNAL_CRYPTO_ENCRYPTOR_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <memory>
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#include <optional>
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#include <string>
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#include <vector>
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#include "absl/strings/string_view.h"
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#include "absl/types/optional.h"
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#include "absl/types/span.h"
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#include "internal/crypto_cros/crypto_export.h"
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namespace nearby::crypto {
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class SymmetricKey;
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// This class implements encryption without authentication, which is usually
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// unsafe. Prefer crypto::Aead for new code. If using this class, prefer the
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// absl::Span and std::vector overloads over the absl::string_view and
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// std::string overloads.
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class CRYPTO_EXPORT Encryptor {
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public:
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enum Mode {
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CBC,
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CTR,
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};
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Encryptor();
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~Encryptor();
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// Initializes the encryptor using |key| and |iv|. Returns false if either the
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// key or the initialization vector cannot be used.
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//
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// If |mode| is CBC, |iv| must not be empty; if it is CTR, then |iv| must be
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// empty.
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bool Init(const SymmetricKey* key, Mode mode, absl::string_view iv);
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bool Init(const SymmetricKey* key, Mode mode, absl::Span<const uint8_t> iv);
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// Encrypts |plaintext| into |ciphertext|. |plaintext| may only be empty if
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// the mode is CBC.
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bool Encrypt(absl::string_view plaintext, std::string* ciphertext);
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bool Encrypt(absl::Span<const uint8_t> plaintext,
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std::vector<uint8_t>* ciphertext);
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// Decrypts |ciphertext| into |plaintext|. |ciphertext| must not be empty.
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//
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// WARNING: In CBC mode, Decrypt() returns false if it detects the padding
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// in the decrypted plaintext is wrong. Padding errors can result from
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// tampered ciphertext or a wrong decryption key. But successful decryption
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// does not imply the authenticity of the data. The caller of Decrypt()
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// must either authenticate the ciphertext before decrypting it, or take
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// care to not report decryption failure. Otherwise it could inadvertently
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// be used as a padding oracle to attack the crypto system.
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bool Decrypt(absl::string_view ciphertext, std::string* plaintext);
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bool Decrypt(absl::Span<const uint8_t> ciphertext,
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std::vector<uint8_t>* plaintext);
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// Sets the counter value when in CTR mode. Currently only 128-bits
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// counter value is supported.
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//
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// Returns true only if update was successful.
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bool SetCounter(absl::string_view counter);
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bool SetCounter(absl::Span<const uint8_t> counter);
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// TODO(albertb): Support streaming encryption.
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private:
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const SymmetricKey* key_;
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Mode mode_;
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bool CryptString(bool do_encrypt, absl::string_view input,
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std::string* output);
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bool CryptBytes(bool do_encrypt, absl::Span<const uint8_t> input,
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std::vector<uint8_t>* output);
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// On success, these helper functions return the number of bytes written to
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// |output|.
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size_t MaxOutput(bool do_encrypt, size_t length);
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absl::optional<size_t> Crypt(bool do_encrypt, absl::Span<const uint8_t> input,
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absl::Span<uint8_t> output);
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absl::optional<size_t> CryptCTR(bool do_encrypt,
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absl::Span<const uint8_t> input,
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absl::Span<uint8_t> output);
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// In CBC mode, the IV passed to Init(). In CTR mode, the counter value passed
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// to SetCounter().
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std::vector<uint8_t> iv_;
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};
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} // namespace nearby::crypto
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#endif // THIRD_PARTY_NEARBY_INTERNAL_CRYPTO_ENCRYPTOR_H_
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