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NAME

       EVP_chacha20, EVP_chacha20_poly1305 - EVP ChaCha20 stream cipher

SYNOPSIS

        #include <openssl/evp.h>

        const EVP_CIPHER *EVP_chacha20(void)
        const EVP_CIPHER *EVP_chacha20_poly1305(void)

DESCRIPTION

       The ChaCha20 stream cipher for EVP.

       EVP_chacha20()
           The ChaCha20 stream cipher. The key length is 256 bits, the IV is 128 bits long.  The
           first 32 bits consists of a counter in little-endian order followed by a 96 bit nonce.
           For example a nonce of:

           000000000000000000000002

           With an initial counter of 42 (2a in hex) would be expressed as:

           2a000000000000000000000000000002

       EVP_chacha20_poly1305()
           Authenticated encryption with ChaCha20-Poly1305. Like EVP_chacha20(), the key is 256
           bits and the IV is 96 bits. This supports additional authenticated data (AAD) and
           produces a 128-bit authentication tag. See the "AEAD Interface" in EVP_EncryptInit(3)
           section for more information.

RETURN VALUES

       These functions return an EVP_CIPHER structure that contains the implementation of the
       symmetric cipher. See EVP_CIPHER_meth_new(3) for details of the EVP_CIPHER structure.

SEE ALSO

       evp(7), EVP_EncryptInit(3), EVP_CIPHER_meth_new(3)

COPYRIGHT

       Copyright 2017-2019 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use this file except in
       compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.