diff --git a/library/arc4.c b/library/arc4.c
new file mode 100644
index 0000000..9ee6dc1
--- /dev/null
+++ b/library/arc4.c
@@ -0,0 +1,201 @@
+/*
+ *  An implementation of the ARCFOUR algorithm
+ *
+ *  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)
+ */
+/*
+ *  The ARCFOUR algorithm was publicly disclosed on 94/09.
+ *
+ *  http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
+ */
+
+#if !defined(MBEDCRYPTO_CONFIG_FILE)
+#include "mbedcrypto/config.h"
+#else
+#include MBEDCRYPTO_CONFIG_FILE
+#endif
+
+#if defined(MBEDCRYPTO_ARC4_C)
+
+#include "mbedcrypto/arc4.h"
+#include "mbedcrypto/platform_util.h"
+
+#include <string.h>
+
+#if defined(MBEDCRYPTO_SELF_TEST)
+#if defined(MBEDCRYPTO_PLATFORM_C)
+#include "mbedcrypto/platform.h"
+#else
+#include <stdio.h>
+#define mbedcrypto_printf printf
+#endif /* MBEDCRYPTO_PLATFORM_C */
+#endif /* MBEDCRYPTO_SELF_TEST */
+
+#if !defined(MBEDCRYPTO_ARC4_ALT)
+
+void mbedcrypto_arc4_init( mbedcrypto_arc4_context *ctx )
+{
+    memset( ctx, 0, sizeof( mbedcrypto_arc4_context ) );
+}
+
+void mbedcrypto_arc4_free( mbedcrypto_arc4_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    mbedcrypto_platform_zeroize( ctx, sizeof( mbedcrypto_arc4_context ) );
+}
+
+/*
+ * ARC4 key schedule
+ */
+void mbedcrypto_arc4_setup( mbedcrypto_arc4_context *ctx, const unsigned char *key,
+                 unsigned int keylen )
+{
+    int i, j, a;
+    unsigned int k;
+    unsigned char *m;
+
+    ctx->x = 0;
+    ctx->y = 0;
+    m = ctx->m;
+
+    for( i = 0; i < 256; i++ )
+        m[i] = (unsigned char) i;
+
+    j = k = 0;
+
+    for( i = 0; i < 256; i++, k++ )
+    {
+        if( k >= keylen ) k = 0;
+
+        a = m[i];
+        j = ( j + a + key[k] ) & 0xFF;
+        m[i] = m[j];
+        m[j] = (unsigned char) a;
+    }
+}
+
+/*
+ * ARC4 cipher function
+ */
+int mbedcrypto_arc4_crypt( mbedcrypto_arc4_context *ctx, size_t length, const unsigned char *input,
+                unsigned char *output )
+{
+    int x, y, a, b;
+    size_t i;
+    unsigned char *m;
+
+    x = ctx->x;
+    y = ctx->y;
+    m = ctx->m;
+
+    for( i = 0; i < length; i++ )
+    {
+        x = ( x + 1 ) & 0xFF; a = m[x];
+        y = ( y + a ) & 0xFF; b = m[y];
+
+        m[x] = (unsigned char) b;
+        m[y] = (unsigned char) a;
+
+        output[i] = (unsigned char)
+            ( input[i] ^ m[(unsigned char)( a + b )] );
+    }
+
+    ctx->x = x;
+    ctx->y = y;
+
+    return( 0 );
+}
+
+#endif /* !MBEDCRYPTO_ARC4_ALT */
+
+#if defined(MBEDCRYPTO_SELF_TEST)
+/*
+ * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
+ *
+ * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
+ */
+static const unsigned char arc4_test_key[3][8] =
+{
+    { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
+    { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
+};
+
+static const unsigned char arc4_test_pt[3][8] =
+{
+    { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
+};
+
+static const unsigned char arc4_test_ct[3][8] =
+{
+    { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
+    { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
+    { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
+};
+
+/*
+ * Checkup routine
+ */
+int mbedcrypto_arc4_self_test( int verbose )
+{
+    int i, ret = 0;
+    unsigned char ibuf[8];
+    unsigned char obuf[8];
+    mbedcrypto_arc4_context ctx;
+
+    mbedcrypto_arc4_init( &ctx );
+
+    for( i = 0; i < 3; i++ )
+    {
+        if( verbose != 0 )
+            mbedcrypto_printf( "  ARC4 test #%d: ", i + 1 );
+
+        memcpy( ibuf, arc4_test_pt[i], 8 );
+
+        mbedcrypto_arc4_setup( &ctx, arc4_test_key[i], 8 );
+        mbedcrypto_arc4_crypt( &ctx, 8, ibuf, obuf );
+
+        if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
+        {
+            if( verbose != 0 )
+                mbedcrypto_printf( "failed\n" );
+
+            ret = 1;
+            goto exit;
+        }
+
+        if( verbose != 0 )
+            mbedcrypto_printf( "passed\n" );
+    }
+
+    if( verbose != 0 )
+        mbedcrypto_printf( "\n" );
+
+exit:
+    mbedcrypto_arc4_free( &ctx );
+
+    return( ret );
+}
+
+#endif /* MBEDCRYPTO_SELF_TEST */
+
+#endif /* MBEDCRYPTO_ARC4_C */