diff --git a/library/psa_crypto_invasive.h b/library/psa_crypto_invasive.h
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+/**
+ * \file psa_crypto_invasive.h
+ *
+ * \brief PSA cryptography module: invasive interfaces for test only.
+ *
+ * The interfaces in this file are intended for testing purposes only.
+ * They MUST NOT be made available to clients over IPC in integrations
+ * with isolation, and they SHOULD NOT be made available in library
+ * integrations except when building the library for testing.
+ */
+/*
+ *  Copyright (C) 2018, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  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 file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+#ifndef PSA_CRYPTO_INVASIVE_H
+#define PSA_CRYPTO_INVASIVE_H
+
+#if defined(MBEDTLS_CONFIG_FILE)
+#include MBEDTLS_CONFIG_FILE
+#else
+#include "mbedtls/config.h"
+#endif
+
+#include "psa/crypto.h"
+
+#include "mbedtls/entropy.h"
+
+/** \brief Configure entropy sources.
+ *
+ * This function may only be called before a call to psa_crypto_init(),
+ * or after a call to mbedtls_psa_crypto_free() and before any
+ * subsequent call to psa_crypto_init().
+ *
+ * This function is only intended for test purposes. The functionality
+ * it provides is also useful for system integrators, but
+ * system integrators should configure entropy drivers instead of
+ * breaking through to the Mbed TLS API.
+ *
+ * \param entropy_init  Function to initialize the entropy context
+ *                      and set up the desired entropy sources.
+ *                      It is called by psa_crypto_init().
+ *                      By default this is mbedtls_entropy_init().
+ *                      This function cannot report failures directly.
+ *                      To indicate a failure, set the entropy context
+ *                      to a state where mbedtls_entropy_func() will
+ *                      return an error.
+ * \param entropy_free  Function to free the entropy context
+ *                      and associated resources.
+ *                      It is called by mbedtls_psa_crypto_free().
+ *                      By default this is mbedtls_entropy_free().
+ *
+ * \retval PSA_SUCCESS
+ *         Success.
+ * \retval PSA_ERROR_NOT_PERMITTED
+ *         The caller does not have the permission to configure
+ *         entropy sources.
+ * \retval PSA_ERROR_BAD_STATE
+ *         The library has already been initialized.
+ */
+psa_status_t mbedtls_psa_crypto_configure_entropy_sources(
+    void (* entropy_init )( mbedtls_entropy_context *ctx ),
+    void (* entropy_free )( mbedtls_entropy_context *ctx ) );
+
+#endif /* PSA_CRYPTO_INVASIVE_H */