Support File Based Encryption
Change-Id: Ib688ddd0c32d3999590cacd86b6d9b18eac336e9
diff --git a/crypto/ext4crypt/HashPassword.cpp b/crypto/ext4crypt/HashPassword.cpp
new file mode 100644
index 0000000..86e067e
--- /dev/null
+++ b/crypto/ext4crypt/HashPassword.cpp
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2016 Team Win Recovery 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.
+ */
+
+/*
+ * This computes the "secret" used by Android as one of the parameters
+ * to decrypt File Based Encryption. The secret is prefixed with
+ * "Android FBE credential hash" padded with 0s to 128 bytes then the
+ * user's password is appended to the end of the 128 bytes. This string
+ * is then hashed with sha512 and the sha512 value is then converted to
+ * hex with upper-case characters.
+ */
+
+#include <stdio.h>
+#include <string>
+#include <stdlib.h>
+#include <openssl/sha.h>
+
+#define PASS_PADDING_SIZE 128
+#define SHA512_HEX_SIZE SHA512_DIGEST_LENGTH * 2
+
+std::string HashPassword(const std::string& Password) {
+ size_t size = PASS_PADDING_SIZE + Password.size();
+ unsigned char* buffer = (unsigned char*)calloc(1, size);
+ const char* prefix = "Android FBE credential hash";
+ memcpy((void*)buffer, (void*)prefix, strlen(prefix));
+ unsigned char* ptr = buffer + PASS_PADDING_SIZE;
+ memcpy((void*)ptr, Password.c_str(), Password.size());
+ unsigned char hash[SHA512_DIGEST_LENGTH];
+ SHA512_CTX sha512;
+ SHA512_Init(&sha512);
+ SHA512_Update(&sha512, buffer, size);
+ SHA512_Final(hash, &sha512);
+ int index = 0;
+ char hex_hash[SHA512_HEX_SIZE + 1];
+ for(index = 0; index < SHA512_DIGEST_LENGTH; index++)
+ sprintf(hex_hash + (index * 2), "%02X", hash[index]);
+ hex_hash[128] = 0;
+ std::string ret = hex_hash;
+ return ret;
+}