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1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ANDROID_VOLD_KEYSTORAGE_H
18 #define ANDROID_VOLD_KEYSTORAGE_H
19 
20 #include "KeyBuffer.h"
21 
22 #include <cstdint>
23 #include <string>
24 #include <vector>
25 
26 namespace android {
27 namespace vold {
28 
29 // Represents the information needed to decrypt a disk encryption key.
30 class KeyAuthentication {
31   public:
KeyAuthentication(const std::string & s)32     KeyAuthentication(const std::string& s) : secret{s} {};
33 
usesKeymaster()34     bool usesKeymaster() const { return secret.empty(); };
35 
36     const std::string secret;
37 };
38 
39 extern const KeyAuthentication kEmptyAuthentication;
40 
41 bool createSecdiscardable(const std::string& path, std::string* hash);
42 bool readSecdiscardable(const std::string& path, std::string* hash);
43 
44 // Create a directory at the named path, and store "key" in it,
45 // in such a way that it can only be retrieved via Keymaster and
46 // can be securely deleted.
47 // It's safe to move/rename the directory after creation.
48 bool storeKey(const std::string& dir, const KeyAuthentication& auth, const KeyBuffer& key);
49 
50 // Create a directory at the named path, and store "key" in it as storeKey
51 // This version creates the key in "tmp_path" then atomically renames "tmp_path"
52 // to "key_path" thereby ensuring that the key is either stored entirely or
53 // not at all.  All the needed files and directories are also fsync'ed to ensure
54 // that the key is actually persisted to disk.
55 bool storeKeyAtomically(const std::string& key_path, const std::string& tmp_path,
56                         const KeyAuthentication& auth, const KeyBuffer& key);
57 
58 // Retrieve the key from the named directory.
59 bool retrieveKey(const std::string& dir, const KeyAuthentication& auth, KeyBuffer* key);
60 
61 // Securely destroy the key stored in the named directory and delete the directory.
62 bool destroyKey(const std::string& dir);
63 
64 bool runSecdiscardSingle(const std::string& file);
65 
66 // Generate wrapped storage key using keymaster. Uses STORAGE_KEY tag in keymaster.
67 bool generateWrappedStorageKey(KeyBuffer* key);
68 // Export the per-boot boot wrapped storage key using keymaster.
69 bool exportWrappedStorageKey(const KeyBuffer& kmKey, KeyBuffer* key);
70 
71 // Set a seed to be mixed into all key storage encryption keys.
72 bool setKeyStorageBindingSeed(const std::vector<uint8_t>& seed);
73 }  // namespace vold
74 }  // namespace android
75 
76 #endif
77