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diff --git a/crypto/ext4crypt/Keymaster4.h b/crypto/ext4crypt/Keymaster4.h
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+++ b/crypto/ext4crypt/Keymaster4.h
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+/*
+ * Copyright (C) 2016 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 ANDROID_TWRP_KEYMASTER_H
+#define ANDROID_TWRP_KEYMASTER_H
+
+#include "KeyBuffer.h"
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include <android-base/macros.h>
+#include <keymasterV4_0/Keymaster.h>
+#include <keymasterV4_0/authorization_set.h>
+
+namespace android {
+namespace vold {
+
+namespace km = ::android::hardware::keymaster::V4_0;
+using KmDevice = km::support::Keymaster;
+
+// C++ wrappers to the Keymaster hidl interface.
+// This is tailored to the needs of KeyStorage, but could be extended to be
+// a more general interface.
+
+// Wrapper for a Keymaster operation handle representing an
+// ongoing Keymaster operation.  Aborts the operation
+// in the destructor if it is unfinished. Methods log failures
+// to LOG(ERROR).
+class KeymasterOperation {
+  public:
+    ~KeymasterOperation();
+    // Is this instance valid? This is false if creation fails, and becomes
+    // false on finish or if an update fails.
+    explicit operator bool() { return mError == km::ErrorCode::OK; }
+    km::ErrorCode errorCode() { return mError; }
+    // Call "update" repeatedly until all of the input is consumed, and
+    // concatenate the output. Return true on success.
+    template <class TI, class TO>
+    bool updateCompletely(TI& input, TO* output) {
+        if (output) output->clear();
+        return updateCompletely(input.data(), input.size(), [&](const char* b, size_t n) {
+            if (output) std::copy(b, b + n, std::back_inserter(*output));
+        });
+    }
+
+    // Finish and write the output to this string, unless pointer is null.
+    bool finish(std::string* output);
+    // Move constructor
+    KeymasterOperation(KeymasterOperation&& rhs) { *this = std::move(rhs); }
+    // Construct an object in an error state for error returns
+    KeymasterOperation() : mDevice{nullptr}, mOpHandle{0}, mError{km::ErrorCode::UNKNOWN_ERROR} {}
+    // Move Assignment
+    KeymasterOperation& operator=(KeymasterOperation&& rhs) {
+        mDevice = rhs.mDevice;
+        rhs.mDevice = nullptr;
+
+        mOpHandle = rhs.mOpHandle;
+        rhs.mOpHandle = 0;
+
+        mError = rhs.mError;
+        rhs.mError = km::ErrorCode::UNKNOWN_ERROR;
+
+        return *this;
+    }
+
+  private:
+    KeymasterOperation(KmDevice* d, uint64_t h)
+        : mDevice{d}, mOpHandle{h}, mError{km::ErrorCode::OK} {}
+    KeymasterOperation(km::ErrorCode error) : mDevice{nullptr}, mOpHandle{0}, mError{error} {}
+
+    bool updateCompletely(const char* input, size_t inputLen,
+                          const std::function<void(const char*, size_t)> consumer);
+
+    KmDevice* mDevice;
+    uint64_t mOpHandle;
+    km::ErrorCode mError;
+    DISALLOW_COPY_AND_ASSIGN(KeymasterOperation);
+    friend class Keymaster;
+};
+
+// Wrapper for a Keymaster device for methods that start a KeymasterOperation or are not
+// part of one.
+class Keymaster {
+  public:
+    Keymaster();
+    // false if we failed to open the keymaster device.
+    explicit operator bool() { return mDevice.get() != nullptr; }
+    // Generate a key in the keymaster from the given params.
+    bool generateKey(const km::AuthorizationSet& inParams, std::string* key);
+    // If the keymaster supports it, permanently delete a key.
+    bool deleteKey(const std::string& key);
+    // Replace stored key blob in response to KM_ERROR_KEY_REQUIRES_UPGRADE.
+    bool upgradeKey(const std::string& oldKey, const km::AuthorizationSet& inParams,
+                    std::string* newKey);
+    // Begin a new cryptographic operation, collecting output parameters if pointer is non-null
+    KeymasterOperation begin(km::KeyPurpose purpose, const std::string& key,
+                             const km::AuthorizationSet& inParams,
+                             const km::HardwareAuthToken& authToken,
+                             km::AuthorizationSet* outParams);
+    bool isSecure();
+
+  private:
+    std::unique_ptr<KmDevice> mDevice;
+    DISALLOW_COPY_AND_ASSIGN(Keymaster);
+    static bool hmacKeyGenerated;
+};
+
+}  // namespace vold
+}  // namespace android
+
+// FIXME no longer needed now cryptfs is in C++.
+
+/*
+ * The following functions provide C bindings to keymaster services
+ * needed by cryptfs scrypt. The compatibility check checks whether
+ * the keymaster implementation is considered secure, i.e., TEE backed.
+ * The create_key function generates an RSA key for signing.
+ * The sign_object function signes an object with the given keymaster
+ * key.
+ */
+
+/* Return values for keymaster_sign_object_for_cryptfs_scrypt */
+
+enum class KeymasterSignResult {
+    ok = 0,
+    error = -1,
+    upgrade = -2,
+};
+
+int keymaster_compatibility_cryptfs_scrypt();
+int keymaster_create_key_for_cryptfs_scrypt(uint32_t rsa_key_size, uint64_t rsa_exponent,
+                                            uint32_t ratelimit, uint8_t* key_buffer,
+                                            uint32_t key_buffer_size, uint32_t* key_out_size);
+
+int keymaster_upgrade_key_for_cryptfs_scrypt(uint32_t rsa_key_size, uint64_t rsa_exponent,
+                                             uint32_t ratelimit, const uint8_t* key_blob,
+                                             size_t key_blob_size, uint8_t* key_buffer,
+                                             uint32_t key_buffer_size, uint32_t* key_out_size);
+
+KeymasterSignResult keymaster_sign_object_for_cryptfs_scrypt(
+    const uint8_t* key_blob, size_t key_blob_size, uint32_t ratelimit, const uint8_t* object,
+    const size_t object_size, uint8_t** signature_buffer, size_t* signature_buffer_size);
+
+#endif