1 files changed, 53 insertions, 0 deletions

diff --git a/crypto/ext4crypt/HashPassword.cpp b/crypto/ext4crypt/HashPassword.cpp
new file mode 100644
index 000000000..86e067ebb
--- /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;
+}