diff --git a/gatekeeper/aidl/software/SharedSecret.h b/gatekeeper/aidl/software/SharedSecret.h
new file mode 100644
index 0000000..1b804e7
--- /dev/null
+++ b/gatekeeper/aidl/software/SharedSecret.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2020, 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.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <mutex>
+
+#include <aidl/android/hardware/security/sharedsecret/BnSharedSecret.h>
+#include <aidl/android/hardware/security/sharedsecret/SharedSecretParameters.h>
+#include <keymaster/km_openssl/soft_keymaster_enforcement.h>
+
+namespace aidl::android::hardware::security::sharedsecret {
+
+class SoftSharedSecret : public BnSharedSecret {
+  public:
+    ::ndk::ScopedAStatus getSharedSecretParameters(SharedSecretParameters* params) override;
+    ::ndk::ScopedAStatus computeSharedSecret(const std::vector<SharedSecretParameters>& params,
+                                             std::vector<uint8_t>* sharingCheck) override;
+
+    keymaster::KeymasterKeyBlob HmacKey() const;
+
+  private:
+    mutable std::mutex mutex_;
+    std::vector<std::uint8_t> seed_;
+    std::vector<std::uint8_t> nonce_;
+    keymaster::KeymasterKeyBlob hmac_key_;
+};
+
+}  // namespace aidl::android::hardware::security::sharedsecret