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/*
* 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/keymaster_types.h>
#include <keystore/keystore.h>
#include <vector>
constexpr size_t kValueSize = 32768;
constexpr size_t kAesKeySize = 128 / 8;
constexpr size_t kGcmTagLength = 128 / 8;
constexpr size_t kGcmIvLength = 96 / 8;
constexpr size_t kAes128KeySizeBytes = 128 / 8;
/* 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 kValueSize 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. */
struct __attribute__((packed)) blobv3 {
uint8_t version;
uint8_t type;
uint8_t flags;
uint8_t info;
uint8_t initialization_vector[AES_BLOCK_SIZE]; // Only 96 bits is used, rest is zeroed.
uint8_t aead_tag[kGcmTagLength];
int32_t length; // in network byte order, only for backward compatibility
uint8_t value[kValueSize + AES_BLOCK_SIZE];
};
struct __attribute__((packed)) blobv2 {
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
uint8_t value[kValueSize + AES_BLOCK_SIZE];
};
static_assert(sizeof(blobv3) == sizeof(blobv2) &&
offsetof(blobv3, initialization_vector) == offsetof(blobv2, vector) &&
offsetof(blobv3, aead_tag) == offsetof(blobv2, digest) &&
offsetof(blobv3, aead_tag) == offsetof(blobv2, encrypted) &&
offsetof(blobv3, length) == offsetof(blobv2, length) &&
offsetof(blobv3, value) == offsetof(blobv2, value),
"Oops. Blob layout changed.");
static const uint8_t CURRENT_BLOB_VERSION = 3;
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,
TYPE_KEY_CHARACTERISTICS = 5,
TYPE_MASTER_KEY_AES256 = 7,
} BlobType;
class Blob {
public:
Blob(const uint8_t* value, size_t valueLength, const uint8_t* info, uint8_t infoLength,
BlobType type);
explicit Blob(blobv3 b);
Blob();
~Blob() { mBlob = {}; }
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 isSuperEncrypted() const;
void setSuperEncrypted(bool superEncrypted);
bool isCriticalToDeviceEncryption() const;
void setCriticalToDeviceEncryption(bool critical);
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); }
keystore::SecurityLevel getSecurityLevel() const;
void setSecurityLevel(keystore::SecurityLevel);
ResponseCode writeBlob(const std::string& filename, const std::vector<uint8_t>& aes_key,
State state);
ResponseCode readBlob(const std::string& filename, const std::vector<uint8_t>& aes_key,
State state);
private:
blobv3 mBlob;
};
#endif // KEYSTORE_BLOB_H_
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