66 lines
2.4 KiB
C++
66 lines
2.4 KiB
C++
//
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// Copyright (C) 2020 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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#pragma once
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#include <optional>
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#include <vector>
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#include <keymaster/serializable.h>
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#include "host/commands/secure_env/tpm_resource_manager.h"
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namespace cuttlefish {
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/**
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* A keymaster::Serializable that wraps another keymaster::Serializable,
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* protecting it from tampering while it is stored elsewhere. This stores
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* the serialized data of the other type together with a signature over that
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* serialized data. When deserializing, it will attempt to make the same
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* signature over the data. If the signature or data has been tampered with,
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* the signatures won't match and it won't attempt to deserialize the wrapped
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* type.
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*
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* The serialization format is:
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* [uint32_t: wrapped_size] [wrapped_data]
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* [uint32_t: signature_size] [signature_data]
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*
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* While this class currently assumes all signatures will use the same key
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* and algorithm and therefore be the same size, the serialization format is
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* future-proof to accommodate signature changes.
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*/
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class HmacSerializable : public keymaster::Serializable {
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public:
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HmacSerializable(TpmResourceManager&,
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std::function<TpmObjectSlot(TpmResourceManager&)>,
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uint32_t digest_size, Serializable*, const Serializable* aad);
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size_t SerializedSize() const override;
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uint8_t* Serialize(uint8_t* buf, const uint8_t* end) const override;
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bool Deserialize(const uint8_t** buf_ptr, const uint8_t* end) override;
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private:
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TpmResourceManager& resource_manager_;
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std::function<TpmObjectSlot(TpmResourceManager&)> signing_key_fn_;
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uint32_t digest_size_;
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Serializable* wrapped_;
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const Serializable* aad_;
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std::optional<std::vector<uint8_t>> AppendAad(const uint8_t* sensitive,
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size_t sensitive_size) const;
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};
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} // namespace cuttlefish
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