| /* |
| * 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_KEYMASTER_CONTEXT_H_ |
| #define SYSTEM_KEYMASTER_KEYMASTER_CONTEXT_H_ |
| |
| #include <assert.h> |
| |
| #include <hardware/keymaster_defs.h> |
| |
| namespace keymaster { |
| |
| class AuthorizationSet; |
| class KeyFactory; |
| class OperationFactory; |
| struct KeymasterKeyBlob; |
| |
| /** |
| * KeymasterContext provides a singleton abstract interface that encapsulates various |
| * environment-dependent elements of AndroidKeymaster. |
| * |
| * AndroidKeymaster runs in multiple contexts. Primarily: |
| * |
| * - In a trusted execution environment (TEE) as a "secure hardware" implementation. In this |
| * context keys are wrapped with an master key that never leaves the TEE, TEE-specific routines |
| * are used for random number generation, all AndroidKeymaster-enforced authorizations are |
| * considered hardware-enforced, and there's a bootloader-provided root of trust. |
| * |
| * - In the non-secure world as a software-only implementation. In this context keys are not |
| * encrypted (though they are integrity-checked) because there is no place to securely store a |
| * key, OpenSSL is used for random number generation, no AndroidKeymaster-enforced authorizations |
| * are considered hardware enforced and the root of trust is a static string. |
| * |
| * - In the non-secure world as a hybrid implementation fronting a less-capable hardware |
| * implementation. For example, a keymaster0 hardware implementation. In this context keys are |
| * not encrypted by AndroidKeymaster, but some may be opaque blobs provided by the backing |
| * hardware, but blobs that lack the extended authorization lists of keymaster1. In addition, |
| * keymaster0 lacks many features of keymaster1, including modes of operation related to the |
| * backing keymaster0 keys. AndroidKeymaster must extend the blobs to add authorization lists, |
| * and must provide the missing operation mode implementations in software, which means that |
| * authorization lists are partially hardware-enforced (the bits that are enforced by the |
| * underlying keymaster0) and partially software-enforced (the rest). OpenSSL is used for number |
| * generation and the root of trust is a static string. |
| * |
| * More contexts are possible. |
| */ |
| class KeymasterContext { |
| public: |
| KeymasterContext() {} |
| virtual ~KeymasterContext(){}; |
| |
| virtual KeyFactory* GetKeyFactory(keymaster_algorithm_t algorithm) const = 0; |
| virtual OperationFactory* GetOperationFactory(keymaster_algorithm_t algorithm, |
| keymaster_purpose_t purpose) const = 0; |
| virtual keymaster_algorithm_t* GetSupportedAlgorithms(size_t* algorithms_count) const = 0; |
| |
| /** |
| * CreateKeyBlob takes authorization sets and key material and produces a key blob and hardware |
| * and software authorization lists ready to be returned to the AndroidKeymaster client |
| * (Keystore, generally). The blob is integrity-checked and may be encrypted, depending on the |
| * needs of the context. |
| * |
| * This method is generally called only by KeyFactory subclassses. |
| */ |
| virtual keymaster_error_t CreateKeyBlob(const AuthorizationSet& key_description, |
| keymaster_key_origin_t origin, |
| const KeymasterKeyBlob& key_material, |
| KeymasterKeyBlob* blob, AuthorizationSet* hw_enforced, |
| AuthorizationSet* sw_enforced) const = 0; |
| |
| /** |
| * ParseKeyBlob takes a blob and extracts authorization sets and key material, returning an |
| * error if the blob fails integrity checking or decryption. Note that the returned key |
| * material may itself be an opaque blob usable only by secure hardware (in the hybrid case). |
| * |
| * This method is called by AndroidKeymaster. |
| */ |
| virtual keymaster_error_t ParseKeyBlob(const KeymasterKeyBlob& blob, |
| const AuthorizationSet& additional_params, |
| KeymasterKeyBlob* key_material, |
| AuthorizationSet* hw_enforced, |
| AuthorizationSet* sw_enforced) const = 0; |
| |
| /** |
| * Take whatever environment-specific action is appropriate (if any) to delete the specified |
| * key. |
| */ |
| virtual keymaster_error_t DeleteKey(const KeymasterKeyBlob& /* blob */) const { |
| return KM_ERROR_OK; |
| } |
| |
| /** |
| * Take whatever environment-specific action is appropriate to delete all keys. |
| */ |
| virtual keymaster_error_t DeleteAllKeys() const { return KM_ERROR_OK; } |
| |
| /** |
| * Adds entropy to the Cryptographic Pseudo Random Number Generator used to generate key |
| * material, and other cryptographic protocol elements. Note that if the underlying CPRNG |
| * tracks the size of its entropy pool, it should not assume that the provided data contributes |
| * any entropy, and it should also ensure that data provided through this interface cannot |
| * "poison" the CPRNG outputs, making them predictable. |
| */ |
| virtual keymaster_error_t AddRngEntropy(const uint8_t* buf, size_t length) const = 0; |
| |
| /** |
| * Generates \p length random bytes, placing them in \p buf. |
| */ |
| virtual keymaster_error_t GenerateRandom(uint8_t* buf, size_t length) const = 0; |
| |
| private: |
| // Uncopyable. |
| KeymasterContext(const KeymasterContext&); |
| void operator=(const KeymasterContext&); |
| }; |
| |
| } // namespace keymaster |
| |
| #endif // SYSTEM_KEYMASTER_KEYMASTER_CONTEXT_H_ |