EVP_chacha20, EVP_chacha20_poly1305 - EVP ChaCha20 stream cipher
 #include <openssl/evp.h>
 const EVP_CIPHER *EVP_chacha20(void)
 const EVP_CIPHER *EVP_chacha20_poly1305(void)
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.
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.
evp(7), EVP_EncryptInit(3), EVP_CIPHER_meth_new(3)
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
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    <https://www.openssl.org/source/license.html>.