| /* |
| * Copyright (C) 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 KEYSTORE_BLOB_H_ |
| #define KEYSTORE_BLOB_H_ |
| |
| #include <stdint.h> |
| |
| #include <openssl/aes.h> |
| #include <openssl/md5.h> |
| |
| #include <keystore/keystore.h> |
| |
| #define VALUE_SIZE 32768 |
| |
| /* Here is the file format. There are two parts in blob.value, the secret and |
| * the description. The secret is stored in ciphertext, and its original size |
| * can be found in blob.length. The description is stored after the secret in |
| * plaintext, and its size is specified in blob.info. The total size of the two |
| * parts must be no more than VALUE_SIZE bytes. The first field is the version, |
| * the second is the blob's type, and the third byte is flags. Fields other |
| * than blob.info, blob.length, and blob.value are modified by encryptBlob() |
| * and decryptBlob(). Thus they should not be accessed from outside. */ |
| |
| /* ** Note to future implementors of encryption: ** |
| * Currently this is the construction: |
| * metadata || Enc(MD5(data) || data) |
| * |
| * This should be the construction used for encrypting if re-implementing: |
| * |
| * Derive independent keys for encryption and MAC: |
| * Kenc = AES_encrypt(masterKey, "Encrypt") |
| * Kmac = AES_encrypt(masterKey, "MAC") |
| * |
| * Store this: |
| * metadata || AES_CTR_encrypt(Kenc, rand_IV, data) || |
| * HMAC(Kmac, metadata || Enc(data)) |
| */ |
| struct __attribute__((packed)) blob { |
| uint8_t version; |
| uint8_t type; |
| uint8_t flags; |
| uint8_t info; |
| uint8_t vector[AES_BLOCK_SIZE]; |
| uint8_t encrypted[0]; // Marks offset to encrypted data. |
| uint8_t digest[MD5_DIGEST_LENGTH]; |
| uint8_t digested[0]; // Marks offset to digested data. |
| int32_t length; // in network byte order when encrypted |
| uint8_t value[VALUE_SIZE + AES_BLOCK_SIZE]; |
| }; |
| |
| static const uint8_t CURRENT_BLOB_VERSION = 2; |
| |
| typedef enum { |
| TYPE_ANY = 0, // meta type that matches anything |
| TYPE_GENERIC = 1, |
| TYPE_MASTER_KEY = 2, |
| TYPE_KEY_PAIR = 3, |
| TYPE_KEYMASTER_10 = 4, |
| } BlobType; |
| |
| class Entropy; |
| |
| class Blob { |
| public: |
| Blob(const uint8_t* value, size_t valueLength, const uint8_t* info, uint8_t infoLength, |
| BlobType type); |
| explicit Blob(blob b); |
| |
| Blob(); |
| |
| const uint8_t* getValue() const { return mBlob.value; } |
| |
| int32_t getLength() const { return mBlob.length; } |
| |
| const uint8_t* getInfo() const { return mBlob.value + mBlob.length; } |
| uint8_t getInfoLength() const { return mBlob.info; } |
| |
| uint8_t getVersion() const { return mBlob.version; } |
| |
| bool isEncrypted() const; |
| void setEncrypted(bool encrypted); |
| |
| bool isFallback() const { return mBlob.flags & KEYSTORE_FLAG_FALLBACK; } |
| void setFallback(bool fallback); |
| |
| void setVersion(uint8_t version) { mBlob.version = version; } |
| BlobType getType() const { return BlobType(mBlob.type); } |
| void setType(BlobType type) { mBlob.type = uint8_t(type); } |
| |
| ResponseCode writeBlob(const char* filename, AES_KEY* aes_key, State state, Entropy* entropy); |
| ResponseCode readBlob(const char* filename, AES_KEY* aes_key, State state); |
| |
| private: |
| struct blob mBlob; |
| }; |
| |
| #endif // KEYSTORE_BLOB_H_ |