1EVP_CHACHA20(3ossl)                 OpenSSL                EVP_CHACHA20(3ossl)
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NAME

6       EVP_chacha20, EVP_chacha20_poly1305 - EVP ChaCha20 stream cipher
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SYNOPSIS

9        #include <openssl/evp.h>
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11        const EVP_CIPHER *EVP_chacha20(void);
12        const EVP_CIPHER *EVP_chacha20_poly1305(void);
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DESCRIPTION

15       The ChaCha20 stream cipher for EVP.
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17       EVP_chacha20()
18           The ChaCha20 stream cipher. The key length is 256 bits, the IV is
19           128 bits long.  The first 32 bits consists of a counter in little-
20           endian order followed by a 96 bit nonce. For example a nonce of:
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22           000000000000000000000002
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24           With an initial counter of 42 (2a in hex) would be expressed as:
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26           2a000000000000000000000000000002
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28       EVP_chacha20_poly1305()
29           Authenticated encryption with ChaCha20-Poly1305. Like
30           EVP_chacha20(), the key is 256 bits and the IV is 96 bits. This
31           supports additional authenticated data (AAD) and produces a 128-bit
32           authentication tag. See the "AEAD Interface" in EVP_EncryptInit(3)
33           section for more information.
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NOTES

36       Developers should be aware of the negative performance implications of
37       calling these functions multiple times and should consider using
38       EVP_CIPHER_fetch(3) instead.  See "Performance" in crypto(7) for
39       further information.
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RETURN VALUES

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

47       evp(7), EVP_EncryptInit(3), EVP_CIPHER_meth_new(3)
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50       Copyright 2017-2023 The OpenSSL Project Authors. All Rights Reserved.
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52       Licensed under the Apache License 2.0 (the "License").  You may not use
53       this file except in compliance with the License.  You can obtain a copy
54       in the file LICENSE in the source distribution or at
55       <https://www.openssl.org/source/license.html>.
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593.1.1                             2023-08-31               EVP_CHACHA20(3ossl)
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