diff --git a/include/psa/crypto_struct.h b/include/psa/crypto_struct.h
new file mode 100644
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+++ b/include/psa/crypto_struct.h
@@ -0,0 +1,177 @@
+/**
+ * \file psa/crypto_struct.h
+ *
+ * \brief PSA cryptography module: Mbed Crypto structured type implementations
+ *
+ * \note This file may not be included directly. Applications must
+ * include psa/crypto.h.
+ *
+ * This file contains the definitions of some data structures with
+ * implementation-specific definitions.
+ *
+ * In implementations with isolation between the application and the
+ * cryptography module, it is expected that the front-end and the back-end
+ * would have different versions of this file.
+ */
+/*
+ *  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 Crypto (https://tls.mbed.org)
+ */
+
+#ifndef PSA_CRYPTO_STRUCT_H
+#define PSA_CRYPTO_STRUCT_H
+
+/* Include the Mbed Crypto configuration file, the way Mbed Crypto does it
+ * in each of its header files. */
+#if !defined(MBEDCRYPTO_CONFIG_FILE)
+#include "../mbedcrypto/config.h"
+#else
+#include MBEDCRYPTO_CONFIG_FILE
+#endif
+
+#include "mbedcrypto/cipher.h"
+#include "mbedcrypto/cmac.h"
+#include "mbedcrypto/gcm.h"
+#include "mbedcrypto/md.h"
+#include "mbedcrypto/md2.h"
+#include "mbedcrypto/md4.h"
+#include "mbedcrypto/md5.h"
+#include "mbedcrypto/ripemd160.h"
+#include "mbedcrypto/sha1.h"
+#include "mbedcrypto/sha256.h"
+#include "mbedcrypto/sha512.h"
+
+struct psa_hash_operation_s
+{
+    psa_algorithm_t alg;
+    union
+    {
+        unsigned dummy; /* Make the union non-empty even with no supported algorithms. */
+#if defined(MBEDCRYPTO_MD2_C)
+        mbedcrypto_md2_context md2;
+#endif
+#if defined(MBEDCRYPTO_MD4_C)
+        mbedcrypto_md4_context md4;
+#endif
+#if defined(MBEDCRYPTO_MD5_C)
+        mbedcrypto_md5_context md5;
+#endif
+#if defined(MBEDCRYPTO_RIPEMD160_C)
+        mbedcrypto_ripemd160_context ripemd160;
+#endif
+#if defined(MBEDCRYPTO_SHA1_C)
+        mbedcrypto_sha1_context sha1;
+#endif
+#if defined(MBEDCRYPTO_SHA256_C)
+        mbedcrypto_sha256_context sha256;
+#endif
+#if defined(MBEDCRYPTO_SHA512_C)
+        mbedcrypto_sha512_context sha512;
+#endif
+    } ctx;
+};
+
+
+typedef struct
+{
+        /** The hash context. */
+        struct psa_hash_operation_s hash_ctx;
+        /** The HMAC part of the context. */
+        uint8_t opad[PSA_HMAC_MAX_HASH_BLOCK_SIZE];
+} psa_hmac_internal_data;
+
+
+struct psa_mac_operation_s
+{
+    psa_algorithm_t alg;
+    unsigned int key_set : 1;
+    unsigned int iv_required : 1;
+    unsigned int iv_set : 1;
+    unsigned int has_input : 1;
+    unsigned int is_sign : 1;
+    uint8_t mac_size;
+    union
+    {
+        unsigned dummy; /* Make the union non-empty even with no supported algorithms. */
+#if defined(MBEDCRYPTO_MD_C)
+        psa_hmac_internal_data hmac;
+#endif
+#if defined(MBEDCRYPTO_CMAC_C)
+        mbedcrypto_cipher_context_t cmac;
+#endif
+    } ctx;
+};
+
+struct psa_cipher_operation_s
+{
+    psa_algorithm_t alg;
+    unsigned int key_set : 1;
+    unsigned int iv_required : 1;
+    unsigned int iv_set : 1;
+    uint8_t iv_size;
+    uint8_t block_size;
+    union
+    {
+        mbedcrypto_cipher_context_t cipher;
+    } ctx;
+};
+
+typedef struct
+{
+    uint8_t *info;
+    size_t info_length;
+    psa_hmac_internal_data hmac;
+    uint8_t prk[PSA_HASH_MAX_SIZE];
+    uint8_t output_block[PSA_HASH_MAX_SIZE];
+#if PSA_HASH_MAX_SIZE > 0xff
+#error "PSA_HASH_MAX_SIZE does not fit in uint8_t"
+#endif
+    uint8_t offset_in_block;
+    uint8_t block_number;
+} psa_hkdf_generator_t;
+
+struct psa_crypto_generator_s
+{
+    psa_algorithm_t alg;
+    size_t capacity;
+    union
+    {
+        struct
+        {
+            uint8_t *data;
+            size_t size;
+        } buffer;
+#if defined(MBEDCRYPTO_MD_C)
+        psa_hkdf_generator_t hkdf;
+#endif
+    } ctx;
+};
+
+#define PSA_CRYPTO_GENERATOR_INIT {0, 0, {{0, 0}}}
+static inline struct psa_crypto_generator_s psa_crypto_generator_init( void )
+{
+    const struct psa_crypto_generator_s v = PSA_CRYPTO_GENERATOR_INIT;
+    return( v );
+}
+
+struct psa_key_policy_s
+{
+    psa_key_usage_t usage;
+    psa_algorithm_t alg;
+};
+
+#endif /* PSA_CRYPTO_STRUCT_H */