64 lines
2.5 KiB
C++
64 lines
2.5 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 <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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* encrypting the data with a TPM to ensure privacy.
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*
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* This implementation randomly generates a unique key which only exists inside
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* the TPM, and uses it to encrypt the data from the other Serializable
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* instance. The encrypted data, together with information about the unique key
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* is stored in the output data. The unique key information is something that
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* can only be decoded using a TPM, which will detect if the key is corrupted.
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* However, this implementation will not detect if the encrypted data is
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* corrupted, which could break the other Serializable instance on
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* deserialization. This class should be used with something else to verify
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* that the data hasn't been tampered with.
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*
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* The serialization format is:
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* [tpm key public data] [tpm key private data]
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* [uint32_t: block_size]
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* [uint32_t: encrypted_length] [encrypted_data]
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*
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* The actual length of [encrypted_data] in the serialized format is
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* [encrypted_length] rounded up to the nearest multiple of [block_size].
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* [encrypted_length] is the true length of the data before encryption, without
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* padding.
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*/
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class EncryptedSerializable : public keymaster::Serializable {
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public:
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EncryptedSerializable(TpmResourceManager&,
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std::function<TpmObjectSlot(TpmResourceManager&)>,
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Serializable&);
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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&)> parent_key_fn_;
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keymaster::Serializable& wrapped_;
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};
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} // namespace cuttlefish
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