Refactor keystore.
This CL isn't nearly as big as it looks. It doesn't change keystore
functionality, it just moves all of the classes out of the former
keystore.cpp into their own .h and .cpp files.
Note that this is a cherry-pick from:
https://android-review.googlesource.com/#/c/194971
Change-Id: Ide326c4f1d03984994d1bd9a76fa68d37da230dc
diff --git a/keystore/blob.h b/keystore/blob.h
new file mode 100644
index 0000000..584e312
--- /dev/null
+++ b/keystore/blob.h
@@ -0,0 +1,111 @@
+/*
+ * 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);
+ 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_