diff --git a/include/mbedtls/chachapoly.h b/include/mbedtls/chachapoly.h
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+++ b/include/mbedtls/chachapoly.h
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+/**
+ * \file chachapoly.h
+ *
+ * \brief ChaCha20-Poly1305 AEAD construction based on RFC 7539.
+ *
+ *  Copyright (C) 2006-2016, 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 MBEDTLS_CHACHAPOLY_H
+#define MBEDTLS_CHACHAPOLY_H
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#define MBEDTLS_ERR_CHACHAPOLY_BAD_INPUT_DATA -0x00047 /**< Invalid input parameter(s). */
+#define MBEDTLS_ERR_CHACHAPOLY_BAD_STATE      -0x00049 /**< The requested operation is not permitted in the current state */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum
+{
+    MBEDTLS_CHACHAPOLY_ENCRYPT,
+    MBEDTLS_CHACHAPOLY_DECRYPT
+}
+mbedtls_chachapoly_mode_t;
+
+#if !defined(MBEDTLS_CHACHAPOLY_ALT)
+
+#include "chacha20.h"
+#include "poly1305.h"
+
+typedef struct
+{
+    mbedtls_chacha20_context chacha20_ctx;      /** ChaCha20 context */
+    mbedtls_poly1305_context poly1305_ctx;      /** Poly1305 context */
+    uint64_t aad_len;                           /** Length (bytes) of the Additional Authenticated Data */
+    uint64_t ciphertext_len;                    /** Length (bytes) of the ciphertext */
+    int state;                                  /** Current state of the context */
+    mbedtls_chachapoly_mode_t mode; /** Cipher mode (encrypt or decrypt) */
+}
+mbedtls_chachapoly_context;
+
+#else /* !MBEDTLS_CHACHAPOLY_ALT */
+#include "chachapoly_alt.h"
+#endif /* !MBEDTLS_CHACHAPOLY_ALT */
+
+/**
+ * \brief               Initialize ChaCha20-Poly1305 context
+ *
+ * \param ctx           ChaCha20-Poly1305 context to be initialized
+ */
+void mbedtls_chachapoly_init( mbedtls_chachapoly_context *ctx );
+
+/**
+ * \brief               Clear ChaCha20-Poly1305 context
+ *
+ * \param ctx           ChaCha20-Poly1305 context to be cleared
+ */
+void mbedtls_chachapoly_free( mbedtls_chachapoly_context *ctx );
+
+/**
+ * \brief               Set the ChaCha20-Poly1305 symmetric encryption key.
+ *
+ * \param ctx           The ChaCha20-Poly1305 context.
+ * \param key           The 256-bit (32 bytes) key.
+ *
+ * \return              MBEDTLS_ERR_CHACHAPOLY_BAD_INPUT_DATA is returned
+ *                      if \p ctx or \p key are NULL.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_chachapoly_setkey( mbedtls_chachapoly_context *ctx,
+                               const unsigned char key[32] );
+
+/**
+ * \brief               Setup ChaCha20-Poly1305 context for encryption or decryption.
+ *
+ * \note                If the context is being used for AAD only (no data to
+ *                      encrypt or decrypt) then \p mode can be set to any value.
+ *
+ * \param ctx           The ChaCha20-Poly1305 context.
+ * \param nonce         The nonce/IV to use for the message. This must be unique
+ *                      for every message encrypted under the same key.
+ * \param mode          Specifies whether the context is used to encrypt or
+ *                      decrypt data.
+ *
+ * \return              MBEDTLS_ERR_CHACHAPOLY_BAD_INPUT_DATA is returned
+ *                      if \p ctx or \p mac are NULL.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_chachapoly_starts( mbedtls_chachapoly_context *ctx,
+                               const unsigned char nonce[12],
+                               mbedtls_chachapoly_mode_t mode );
+
+/**
+ * \brief               Process additional authenticated data (AAD).
+ *
+ *                      This function processes data that is authenticated, but
+ *                      not encrypted.
+ *
+ * \note                This function is called before data is encrypted/decrypted.
+ *                      I.e. call this function to process the AAD before calling
+ *                      mbedtls_chachapoly_update.
+ *
+ *                      You may call this function multiple times to process
+ *                      an arbitrary amount of AAD. It is permitted to call
+ *                      this function 0 times, if no AAD is used.
+ *
+ *                      This function cannot be called any more if data has
+ *                      been processed by mbedtls_chachapoly_update,
+ *                      or if the context has been finished.
+ *
+ * \param ctx           The ChaCha20-Poly1305 context.
+ * \param aad_len       The length (in bytes) of the AAD. The length has no
+ *                      restrictions.
+ * \param aad           Buffer containing the AAD.
+ *                      This pointer can be NULL if aad_len == 0.
+ *
+ * \return              MBEDTLS_ERR_CHACHAPOLY_BAD_INPUT_DATA is returned
+ *                      if \p ctx or \p aad are NULL.
+ *                      MBEDTLS_ERR_CHACHAPOLY_BAD_STATE is returned if
+ *                      the context has not been setup, the context has been
+ *                      finished, or if the AAD has been finished.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_chachapoly_update_aad( mbedtls_chachapoly_context *ctx,
+                                   size_t aad_len,
+                                   const unsigned char *aad );
+
+/**
+ * \brief               Encrypt/decrypt data.
+ *
+ *                      The direction (encryption or decryption) depends on the
+ *                      mode that was given when calling
+ *                      mbedtls_chachapoly_starts.
+ *
+ *                      You may call this function multiple times to process
+ *                      an arbitrary amount of data. It is permitted to call
+ *                      this function 0 times, if no data is to be encrypted
+ *                      or decrypted.
+ *
+ * \param ctx           The ChaCha20-Poly1305 context.
+ * \param len           The length (in bytes) of the data to encrypt or decrypt.
+ * \param input         Buffer containing the data to encrypt or decrypt.
+ *                      This pointer can be NULL if len == 0.
+ * \param output        Buffer to where the encrypted or decrypted data is written.
+ *                      This pointer can be NULL if len == 0.
+ *
+ * \return              MBEDTLS_ERR_CHACHAPOLY_BAD_INPUT_DATA is returned
+ *                      if \p ctx, \p input, or \p output are NULL.
+ *                      MBEDTLS_ERR_CHACHAPOLY_BAD_STATE is returned if
+ *                      the context has not been setup, or if the context has been
+ *                      finished.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_chachapoly_update( mbedtls_chachapoly_context *ctx,
+                               size_t len,
+                               const unsigned char *input,
+                               unsigned char *output );
+
+/**
+ * \brief               Compute the ChaCha20-Poly1305 MAC.
+ *
+ * \param ctx           The ChaCha20-Poly1305 context.
+ * \param mac           Buffer to where the 128-bit (16 bytes) MAC is written.
+ *
+ * \return              MBEDTLS_ERR_CHACHAPOLY_BAD_INPUT_DATA is returned
+ *                      if \p ctx or \p mac are NULL.
+ *                      MBEDTLS_ERR_CHACHAPOLY_BAD_STATE is returned if
+ *                      the context has not been setup.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_chachapoly_finish( mbedtls_chachapoly_context *ctx,
+                               unsigned char mac[16] );
+
+/**
+ * \brief               Encrypt or decrypt data, and produce a MAC with ChaCha20-Poly1305.
+ *
+ * \param key           The 256-bit (32 bytes) encryption key to use.
+ * \param nonce         The 96-bit (12 bytes) nonce/IV to use.
+ * \param mode          Specifies whether the data in the \p input buffer is to
+ *                      be encrypted or decrypted. If there is no data to encrypt
+ *                      or decrypt (i.e. \p ilen is 0) then the value of this
+ *                      parameter does not matter.
+ * \param aad_len       The length (in bytes) of the AAD data to process.
+ * \param aad           Buffer containing the additional authenticated data (AAD).
+ *                      This pointer can be NULL if aad_len == 0.
+ * \param ilen          The length (in bytes) of the data to encrypt or decrypt.
+ * \param input         Buffer containing the data to encrypt or decrypt.
+ *                      This pointer can be NULL if ilen == 0.
+ * \param output        Buffer to where the encrypted or decrypted data is written.
+ *                      This pointer can be NULL if ilen == 0.
+ * \param mac           Buffer to where the computed 128-bit (16 bytes) MAC is written.
+ *
+ * \return              MBEDTLS_ERR_CHACHAPOLY_BAD_INPUT_DATA is returned
+ *                      if one or more of the required parameters are NULL.
+ *                      Otherwise, 0 is returned to indicate success.
+ */
+int mbedtls_chachapoly_crypt_and_mac( const unsigned char key[32],
+                                      const unsigned char nonce[12],
+                                      mbedtls_chachapoly_mode_t mode,
+                                      size_t aad_len,
+                                      const unsigned char *aad,
+                                      size_t ilen,
+                                      const unsigned char *input,
+                                      unsigned char *output,
+                                      unsigned char mac[16] );
+
+/**
+ * \brief               Checkup routine
+ *
+ * \return              0 if successful, or 1 if the test failed
+ */
+int mbedtls_chachapoly_self_test( int verbose );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MBEDTLS_CHACHAPOLY_H */