diff --git a/include/mbedcrypto/arc4.h b/include/mbedcrypto/arc4.h
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+++ b/include/mbedcrypto/arc4.h
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+/**
+ * \file arc4.h
+ *
+ * \brief The ARCFOUR stream cipher
+ *
+ * \warning   ARC4 is considered a weak cipher and its use constitutes a
+ *            security risk. We recommend considering stronger ciphers instead.
+ */
+/*
+ *  Copyright (C) 2006-2015, 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 MBEDCRYPTO_ARC4_H
+#define MBEDCRYPTO_ARC4_H
+
+#if !defined(MBEDCRYPTO_CONFIG_FILE)
+#include "config.h"
+#else
+#include MBEDCRYPTO_CONFIG_FILE
+#endif
+
+#include <stddef.h>
+
+#define MBEDCRYPTO_ERR_ARC4_HW_ACCEL_FAILED                  -0x0019  /**< ARC4 hardware accelerator failed. */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if !defined(MBEDCRYPTO_ARC4_ALT)
+// Regular implementation
+//
+
+/**
+ * \brief     ARC4 context structure
+ *
+ * \warning   ARC4 is considered a weak cipher and its use constitutes a
+ *            security risk. We recommend considering stronger ciphers instead.
+ *
+ */
+typedef struct
+{
+    int x;                      /*!< permutation index */
+    int y;                      /*!< permutation index */
+    unsigned char m[256];       /*!< permutation table */
+}
+mbedcrypto_arc4_context;
+
+#else  /* MBEDCRYPTO_ARC4_ALT */
+#include "arc4_alt.h"
+#endif /* MBEDCRYPTO_ARC4_ALT */
+
+/**
+ * \brief          Initialize ARC4 context
+ *
+ * \param ctx      ARC4 context to be initialized
+ *
+ * \warning        ARC4 is considered a weak cipher and its use constitutes a
+ *                 security risk. We recommend considering stronger ciphers
+ *                 instead.
+ *
+ */
+void mbedcrypto_arc4_init( mbedcrypto_arc4_context *ctx );
+
+/**
+ * \brief          Clear ARC4 context
+ *
+ * \param ctx      ARC4 context to be cleared
+ *
+ * \warning        ARC4 is considered a weak cipher and its use constitutes a
+ *                 security risk. We recommend considering stronger ciphers
+ *                 instead.
+ *
+ */
+void mbedcrypto_arc4_free( mbedcrypto_arc4_context *ctx );
+
+/**
+ * \brief          ARC4 key schedule
+ *
+ * \param ctx      ARC4 context to be setup
+ * \param key      the secret key
+ * \param keylen   length of the key, in bytes
+ *
+ * \warning        ARC4 is considered a weak cipher and its use constitutes a
+ *                 security risk. We recommend considering stronger ciphers
+ *                 instead.
+ *
+ */
+void mbedcrypto_arc4_setup( mbedcrypto_arc4_context *ctx, const unsigned char *key,
+                 unsigned int keylen );
+
+/**
+ * \brief          ARC4 cipher function
+ *
+ * \param ctx      ARC4 context
+ * \param length   length of the input data
+ * \param input    buffer holding the input data
+ * \param output   buffer for the output data
+ *
+ * \return         0 if successful
+ *
+ * \warning        ARC4 is considered a weak cipher and its use constitutes a
+ *                 security risk. We recommend considering stronger ciphers
+ *                 instead.
+ *
+ */
+int mbedcrypto_arc4_crypt( mbedcrypto_arc4_context *ctx, size_t length, const unsigned char *input,
+                unsigned char *output );
+
+/**
+ * \brief          Checkup routine
+ *
+ * \return         0 if successful, or 1 if the test failed
+ *
+ * \warning        ARC4 is considered a weak cipher and its use constitutes a
+ *                 security risk. We recommend considering stronger ciphers
+ *                 instead.
+ *
+ */
+int mbedcrypto_arc4_self_test( int verbose );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* arc4.h */