Add SHA-3 module.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
diff --git a/ChangeLog.d/sha3.txt b/ChangeLog.d/sha3.txt
new file mode 100644
index 0000000..dafff74
--- /dev/null
+++ b/ChangeLog.d/sha3.txt
@@ -0,0 +1,3 @@
+Features
+    * Add SHA3 family hash functions.
+
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 8b2b9ea..b23b749 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -78,6 +78,7 @@
  * SHA1      1                  0x0035-0x0035 0x0073-0x0073
  * SHA256    1                  0x0037-0x0037 0x0074-0x0074
  * SHA512    1                  0x0039-0x0039 0x0075-0x0075
+ * SHA-3    1 0x0076-0x0076
  * CHACHA20  3                  0x0051-0x0055
  * POLY1305  3                  0x0057-0x005B
  * CHACHAPOLY 2 0x0054-0x0056
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 2d32f67..35a4a0c 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -328,6 +328,7 @@
 //#define MBEDTLS_SHA1_ALT
 //#define MBEDTLS_SHA256_ALT
 //#define MBEDTLS_SHA512_ALT
+//#define MBEDTLS_SHA3_ALT
 
 /*
  * When replacing the elliptic curve module, pleace consider, that it is
@@ -2864,6 +2865,17 @@
 #define MBEDTLS_SHA512_C
 
 /**
+ * \def MBEDTLS_SHA3_C
+ *
+ * Enable the SHA3 cryptographic hash algorithm.
+ *
+ * Module:  library/sha3.c
+ *
+ * This module adds support for SHA3.
+ */
+#define MBEDTLS_SHA3_C
+
+/**
  * \def MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
  *
  * Enable acceleration of the SHA-512 cryptographic hash algorithm with the
diff --git a/include/mbedtls/sha3.h b/include/mbedtls/sha3.h
new file mode 100644
index 0000000..adecdc7
--- /dev/null
+++ b/include/mbedtls/sha3.h
@@ -0,0 +1,198 @@
+/**
+ * \file sha3.h
+ *
+ * \brief This file contains SHA3 definitions and functions.
+ *
+ * The Secure Hash Algorithms cryptographic
+ * hash functions are defined in <em>FIPS 202: SHA-3 Standard:
+ * Permutation-Based Hash and Extendable-Output Functions </em>.
+ */
+/*
+ *  Copyright The Mbed TLS Contributors
+ *  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.
+ */
+
+#ifndef MBEDTLS_SHA3_H
+#define MBEDTLS_SHA3_H
+#include "mbedtls/private_access.h"
+
+#include "mbedtls/build_info.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** SHA3 input data was malformed. */
+#define MBEDTLS_ERR_SHA3_BAD_INPUT_DATA                 -0x0076
+
+/**
+ * SHA-3 family id.
+ *
+ * It identifies the family (SHA3-256, SHA3-512, etc.)
+ */
+
+typedef enum
+{
+    MBEDTLS_SHA3_NONE = 0, /*!< Operation not defined. */
+    MBEDTLS_SHA3_224, /*!< SHA3-224 */
+    MBEDTLS_SHA3_256, /*!< SHA3-256 */
+    MBEDTLS_SHA3_384, /*!< SHA3-384 */
+    MBEDTLS_SHA3_512, /*!< SHA3-512 */
+} mbedtls_sha3_id;
+
+#if !defined(MBEDTLS_SHA3_ALT)
+// Regular implementation
+//
+
+struct mbedtls_sha3_context;
+typedef struct mbedtls_sha3_family_functions
+{
+    mbedtls_sha3_id id;
+
+    uint16_t r;
+    uint16_t olen;
+    uint8_t xor_byte;
+}
+mbedtls_sha3_family_functions;
+
+/**
+ * \brief          The SHA-3 context structure.
+ *
+ *                 The structure is used SHA-3 checksum calculations.
+ */
+typedef struct mbedtls_sha3_context {
+    uint64_t state[25];
+    uint8_t index;
+    uint8_t id;
+
+    uint16_t r;
+    uint16_t olen;
+    uint8_t xor_byte;
+    uint16_t max_block_size;
+}
+mbedtls_sha3_context;
+
+#else  /* MBEDTLS_SHA3_ALT */
+#include "sha3_alt.h"
+#endif /* MBEDTLS_SHA3_ALT */
+
+/**
+ * \brief          This function initializes a SHA-3 context.
+ *
+ * \param ctx      The SHA-3 context to initialize. This must not be \c NULL.
+ */
+void mbedtls_sha3_init( mbedtls_sha3_context *ctx );
+
+/**
+ * \brief          This function clears a SHA-3 context.
+ *
+ * \param ctx      The SHA-3 context to clear. This may be \c NULL, in which
+ *                 case this function returns immediately. If it is not \c NULL,
+ *                 it must point to an initialized SHA-3 context.
+ */
+void mbedtls_sha3_free( mbedtls_sha3_context *ctx );
+
+/**
+ * \brief          This function clones the state of a SHA-3 context.
+ *
+ * \param dst      The destination context. This must be initialized.
+ * \param src      The context to clone. This must be initialized.
+ */
+void mbedtls_sha3_clone( mbedtls_sha3_context *dst,
+                           const mbedtls_sha3_context *src );
+
+/**
+ * \brief          This function starts a SHA-3 checksum
+ *                 calculation.
+ *
+ * \param ctx      The context to use. This must be initialized.
+ * \param id       The id of the SHA-3 family.
+ *
+ * \return         \c 0 on success.
+ * \return         A negative error code on failure.
+ */
+int mbedtls_sha3_starts( mbedtls_sha3_context *ctx, mbedtls_sha3_id id );
+
+/**
+ * \brief          This function feeds an input buffer into an ongoing
+ *                 SHA-3 checksum calculation.
+ *
+ * \param ctx      The SHA-3 context. This must be initialized
+ *                 and have a hash operation started.
+ * \param input    The buffer holding the data. This must be a readable
+ *                 buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data in Bytes.
+ *
+ * \return         \c 0 on success.
+ * \return         A negative error code on failure.
+ */
+int mbedtls_sha3_update( mbedtls_sha3_context *ctx,
+                           const uint8_t *input,
+                           size_t ilen );
+
+/**
+ * \brief          This function finishes the SHA-3 operation, and writes
+ *                 the result to the output buffer.
+ *
+ * \param ctx      The SHA-3 context. This must be initialized
+ *                 and have a hash operation started.
+ * \param output   The SHA-3 checksum result.
+ *                 This must be a writable buffer of length \c olen bytes.
+ * \param olen     Defines a variable output length (in bytes). \c output must be
+ *                 \c olen bytes length. For SHA-3 224, SHA-3 256, SHA-3 384 and
+ *                 SHA-3 512 must equal to 28, 32, 48 and 64, respectively.
+ *
+ * \return         \c 0 on success.
+ * \return         A negative error code on failure.
+ */
+int mbedtls_sha3_finish( mbedtls_sha3_context *ctx,
+                           uint8_t *output, size_t olen );
+
+/**
+ * \brief          This function calculates the SHA-3
+ *                 checksum of a buffer.
+ *
+ *                 The function allocates the context, performs the
+ *                 calculation, and frees the context.
+ *
+ *                 The SHA-3 result is calculated as
+ *                 output = SHA-3(id, input buffer, d).
+ *
+ * \param id       The id of the SHA-3 family.
+ * \param input    The buffer holding the data. This must be a readable
+ *                 buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data in Bytes.
+ * \param output   The SHA-3 checksum result.
+ *                 This must be a writable buffer of length \c olen bytes.
+ * \param olen     Determines the length (in bytes) of the output. \c output
+ *                 must be \c olen bytes length.
+ *
+ * \return         \c 0 on success.
+ * \return         A negative error code on failure.
+ */
+int mbedtls_sha3( mbedtls_sha3_id id, const uint8_t *input,
+                    size_t ilen,
+                    uint8_t *output,
+                    size_t olen );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* mbedtls_sha3.h */
+
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 6bb2ad3..f1b0d76 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -77,6 +77,7 @@
     sha1.c
     sha256.c
     sha512.c
+    sha3.c
     ssl_debug_helpers_generated.c
     threading.c
     timing.c
diff --git a/library/Makefile b/library/Makefile
index d267e05..79ea185 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -142,6 +142,7 @@
 	     sha1.o \
 	     sha256.o \
 	     sha512.o \
+	     sha3.o \
 	     ssl_debug_helpers_generated.o \
 	     threading.o \
 	     timing.o \
diff --git a/library/sha3.c b/library/sha3.c
new file mode 100644
index 0000000..d5db165
--- /dev/null
+++ b/library/sha3.c
@@ -0,0 +1,305 @@
+/*
+ *  FIPS-202 compliant SHA3 implementation
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  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.
+ */
+/*
+ *  The SHA-3 Secure Hash Standard was published by NIST in 2015.
+ *
+ *  https://nvlpubs.nist.gov/nistpubs/fips/nist.fips.202.pdf
+ */
+
+#include "common.h"
+
+#if defined(MBEDTLS_SHA3_C)
+
+#include "mbedtls/sha3.h"
+#include "mbedtls/platform_util.h"
+#include "mbedtls/error.h"
+
+#include <string.h>
+
+#if defined(MBEDTLS_SELF_TEST)
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdio.h>
+#include <stdlib.h>
+#define mbedtls_printf printf
+#define mbedtls_calloc    calloc
+#define mbedtls_free       free
+#endif /* MBEDTLS_PLATFORM_C */
+#endif /* MBEDTLS_SELF_TEST */
+
+#if !defined(MBEDTLS_SHA3_ALT)
+
+/*
+ * List of supported SHA-3 families
+ */
+static mbedtls_sha3_family_functions sha3_families[] = {
+    { MBEDTLS_SHA3_224,      1152, 224, 0x06 },
+    { MBEDTLS_SHA3_256,      1088, 256, 0x06 },
+    { MBEDTLS_SHA3_384,       832, 384, 0x06 },
+    { MBEDTLS_SHA3_512,       576, 512, 0x06 },
+    { MBEDTLS_SHA3_NONE, 0, 0, 0 }
+};
+
+static const uint64_t rc[24] = {
+    0x0000000000000001, 0x0000000000008082, 0x800000000000808a, 0x8000000080008000,
+    0x000000000000808b, 0x0000000080000001, 0x8000000080008081, 0x8000000000008009,
+    0x000000000000008a, 0x0000000000000088, 0x0000000080008009, 0x000000008000000a,
+    0x000000008000808b, 0x800000000000008b, 0x8000000000008089, 0x8000000000008003,
+    0x8000000000008002, 0x8000000000000080, 0x000000000000800a, 0x800000008000000a,
+    0x8000000080008081, 0x8000000000008080, 0x0000000080000001, 0x8000000080008008,
+};
+
+static const uint8_t rho[24] = {
+    1, 62, 28, 27, 36, 44,  6, 55, 20,
+    3, 10, 43, 25, 39, 41, 45, 15,
+    21,  8, 18,  2, 61, 56, 14
+};
+
+static const uint8_t pi[24] = {
+    10,  7, 11, 17, 18, 3,  5, 16,  8, 21, 24, 4,
+    15, 23, 19, 13, 12, 2, 20, 14, 22,  9,  6, 1,
+};
+
+#define ROT64( x , y ) ( ( ( x ) << ( y ) ) | ( ( x ) >> ( 64U - ( y ) ) ) )
+#define ABSORB( ctx, idx, v ) do { ctx->state[( idx ) >> 3] ^= ( ( uint64_t ) ( v ) ) << ( ( ( idx ) & 0x7 ) << 3 ); } while( 0 )
+#define SQUEEZE( ctx, idx ) ( ( uint8_t )( ctx->state[( idx ) >> 3] >> ( ( ( idx ) & 0x7 ) << 3 ) ) )
+#define SWAP( x, y ) do { uint64_t tmp = ( x ); ( x ) = ( y ); ( y ) = tmp; } while( 0 )
+
+/* The permutation function.  */
+static void keccak_f1600(mbedtls_sha3_context *ctx)
+{
+    uint64_t lane[5];
+    uint64_t *s = ctx->state;
+    int i;
+
+    for( int round = 0; round < 24; round++ )
+    {
+        uint64_t t;
+
+        /* Theta */
+        lane[0] = s[0] ^ s[5] ^ s[10] ^ s[15] ^ s[20];
+        lane[1] = s[1] ^ s[6] ^ s[11] ^ s[16] ^ s[21];
+        lane[2] = s[2] ^ s[7] ^ s[12] ^ s[17] ^ s[22];
+        lane[3] = s[3] ^ s[8] ^ s[13] ^ s[18] ^ s[23];
+        lane[4] = s[4] ^ s[9] ^ s[14] ^ s[19] ^ s[24];
+
+        t = lane[4] ^ ROT64( lane[1], 1 );
+        s[0] ^= t; s[5] ^= t; s[10] ^= t; s[15] ^= t; s[20] ^= t;
+
+        t = lane[0] ^ ROT64( lane[2], 1 );
+        s[1] ^= t; s[6] ^= t; s[11] ^= t; s[16] ^= t; s[21] ^= t;
+
+        t = lane[1] ^ ROT64( lane[3], 1 );
+        s[2] ^= t; s[7] ^= t; s[12] ^= t; s[17] ^= t; s[22] ^= t;
+
+        t = lane[2] ^ ROT64( lane[4], 1 );
+        s[3] ^= t; s[8] ^= t; s[13] ^= t; s[18] ^= t; s[23] ^= t;
+
+        t = lane[3] ^ ROT64( lane[0], 1 );
+        s[4] ^= t; s[9] ^= t; s[14] ^= t; s[19] ^= t; s[24] ^= t;
+
+        /* Rho */
+        for( i = 1; i < 25; i++ )
+            s[i] = ROT64( s[i], rho[i-1] );
+
+        /* Pi */
+        t = s[1];
+        for( i = 0; i < 24; i++ )
+            SWAP( s[pi[i]], t );
+
+        /* Chi */
+        lane[0] = s[0]; lane[1] = s[1]; lane[2] = s[2]; lane[3] = s[3]; lane[4] = s[4];
+        s[0] ^= (~lane[1]) & lane[2];
+        s[1] ^= (~lane[2]) & lane[3];
+        s[2] ^= (~lane[3]) & lane[4];
+        s[3] ^= (~lane[4]) & lane[0];
+        s[4] ^= (~lane[0]) & lane[1];
+
+        lane[0] = s[5]; lane[1] = s[6]; lane[2] = s[7]; lane[3] = s[8]; lane[4] = s[9];
+        s[5] ^= (~lane[1]) & lane[2];
+        s[6] ^= (~lane[2]) & lane[3];
+        s[7] ^= (~lane[3]) & lane[4];
+        s[8] ^= (~lane[4]) & lane[0];
+        s[9] ^= (~lane[0]) & lane[1];
+
+        lane[0] = s[10]; lane[1] = s[11]; lane[2] = s[12]; lane[3] = s[13]; lane[4] = s[14];
+        s[10] ^= (~lane[1]) & lane[2];
+        s[11] ^= (~lane[2]) & lane[3];
+        s[12] ^= (~lane[3]) & lane[4];
+        s[13] ^= (~lane[4]) & lane[0];
+        s[14] ^= (~lane[0]) & lane[1];
+
+        lane[0] = s[15]; lane[1] = s[16]; lane[2] = s[17]; lane[3] = s[18]; lane[4] = s[19];
+        s[15] ^= (~lane[1]) & lane[2];
+        s[16] ^= (~lane[2]) & lane[3];
+        s[17] ^= (~lane[3]) & lane[4];
+        s[18] ^= (~lane[4]) & lane[0];
+        s[19] ^= (~lane[0]) & lane[1];
+
+        lane[0] = s[20]; lane[1] = s[21]; lane[2] = s[22]; lane[3] = s[23]; lane[4] = s[24];
+        s[20] ^= (~lane[1]) & lane[2];
+        s[21] ^= (~lane[2]) & lane[3];
+        s[22] ^= (~lane[3]) & lane[4];
+        s[23] ^= (~lane[4]) & lane[0];
+        s[24] ^= (~lane[0]) & lane[1];
+
+        /* Iota */
+        s[0] ^= rc[round];
+    }
+}
+
+void mbedtls_sha3_init( mbedtls_sha3_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    memset( ctx, 0, sizeof( mbedtls_sha3_context ) );
+}
+
+void mbedtls_sha3_free( mbedtls_sha3_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_sha3_context ) );
+}
+
+void mbedtls_sha3_clone( mbedtls_sha3_context *dst,
+                                    const mbedtls_sha3_context *src )
+{
+    if ( dst == NULL || src == NULL )
+        return;
+
+    *dst = *src;
+}
+
+/*
+ * SHA-3 context setup
+ */
+int mbedtls_sha3_starts( mbedtls_sha3_context *ctx, mbedtls_sha3_id id )
+{
+    mbedtls_sha3_family_functions *p = NULL;
+    if( ctx == NULL )
+        return( MBEDTLS_ERR_SHA3_BAD_INPUT_DATA );
+
+    for( p = sha3_families; p->id != MBEDTLS_SHA3_NONE; p++ )
+    {
+        if( p->id == id )
+            break;
+    }
+
+    if( p == NULL )
+        return( MBEDTLS_ERR_SHA3_BAD_INPUT_DATA );
+
+    ctx->id = id;
+    ctx->r = p->r;
+    ctx->olen = p->olen / 8;
+    ctx->xor_byte = p->xor_byte;
+    ctx->max_block_size = ctx->r / 8;
+
+    return( 0 );
+}
+
+/*
+ * SHA-3 process buffer
+ */
+int mbedtls_sha3_update( mbedtls_sha3_context *ctx,
+                                   const uint8_t *input,
+                                   size_t ilen )
+{
+    if( ctx == NULL )
+        return( MBEDTLS_ERR_SHA3_BAD_INPUT_DATA );
+
+    if( ilen == 0 || input == NULL )
+        return( 0 );
+
+    while( ilen-- > 0 )
+    {
+        ABSORB( ctx, ctx->index, *input++ );
+        if( ( ctx->index = ( ctx->index + 1) % ctx->max_block_size ) == 0 )
+            keccak_f1600( ctx );
+    }
+
+    return( 0 );
+}
+
+int mbedtls_sha3_finish( mbedtls_sha3_context *ctx,
+                              uint8_t *output, size_t olen )
+{
+    if( ctx == NULL )
+        return( MBEDTLS_ERR_SHA3_BAD_INPUT_DATA );
+
+    if( olen == 0 )
+        return( 0 );
+
+    if( ctx->olen > 0 && ctx->olen != olen )
+        return( MBEDTLS_ERR_SHA3_BAD_INPUT_DATA );
+
+    ABSORB( ctx, ctx->index, ctx->xor_byte );
+    ABSORB( ctx, ctx->max_block_size - 1, 0x80 );
+    keccak_f1600( ctx );
+    ctx->index = 0;
+
+    while( olen-- > 0 )
+    {
+        *output++ = SQUEEZE( ctx, ctx->index );
+
+        if( ( ctx->index = ( ctx->index + 1) % ctx->max_block_size ) == 0 )
+            keccak_f1600( ctx );
+    }
+
+    return( 0 );
+}
+
+#endif /* !MBEDTLS_SHA3_ALT */
+
+/*
+ * output = SHA3( input buffer )
+ */
+int mbedtls_sha3( mbedtls_sha3_id id, const uint8_t *input,
+                                size_t ilen, uint8_t *output, size_t olen )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    mbedtls_sha3_context ctx;
+
+    if( ilen != 0 && input == NULL )
+        return( MBEDTLS_ERR_SHA3_BAD_INPUT_DATA );
+
+    if( output == NULL )
+        return( MBEDTLS_ERR_SHA3_BAD_INPUT_DATA );
+
+    mbedtls_sha3_init( &ctx );
+
+    if( ( ret = mbedtls_sha3_starts( &ctx, id ) ) != 0 )
+        goto exit;
+
+    if( ( ret = mbedtls_sha3_update( &ctx, input, ilen ) ) != 0 )
+        goto exit;
+
+    if( ( ret = mbedtls_sha3_finish( &ctx, output, olen ) ) != 0 )
+        goto exit;
+
+exit:
+    mbedtls_sha3_free( &ctx );
+
+    return( ret );
+}
+
+#endif /* MBEDTLS_SHA3_C */
diff --git a/scripts/generate_errors.pl b/scripts/generate_errors.pl
index 0a03f02..a0808ca 100755
--- a/scripts/generate_errors.pl
+++ b/scripts/generate_errors.pl
@@ -49,7 +49,7 @@
                             CAMELLIA CCM CHACHA20 CHACHAPOLY CMAC CTR_DRBG DES
                             ENTROPY ERROR GCM HKDF HMAC_DRBG MD5
                             NET OID PADLOCK PBKDF2 PLATFORM POLY1305 RIPEMD160
-                            SHA1 SHA256 SHA512 THREADING );
+                            SHA1 SHA256 SHA512 SHA3 THREADING );
 my @high_level_modules = qw( CIPHER DHM ECP MD
                              PEM PK PKCS12 PKCS5
                              RSA SSL X509 );
diff --git a/tests/include/alt-dummy/sha3_alt.h b/tests/include/alt-dummy/sha3_alt.h
new file mode 100644
index 0000000..7f9345e
--- /dev/null
+++ b/tests/include/alt-dummy/sha3_alt.h
@@ -0,0 +1,30 @@
+/* sha3_alt.h with dummy types for MBEDTLS_SHA3_ALT */
+/*
+ *  Copyright The Mbed TLS Contributors
+ *  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.
+ */
+
+#ifndef SHA3_ALT_H
+#define SHA3_ALT_H
+
+typedef struct mbedtls_sha3_context
+{
+    int dummy;
+}
+mbedtls_sha3_context;
+
+
+#endif /* sha3_alt.h */
+