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e798248c84
Clearly document that implicit fetching is slower when using providers, and explain prefetching. Added to crypto.pod and migration_guide.pod links to it. Add a link to EVP_default_properties_enable_fips() in crypto.pod. Reviewed-by: Matt Caswell <matt@openssl.org> Reviewed-by: Paul Dale <pauli@openssl.org> (Merged from https://github.com/openssl/openssl/pull/20354)
73 lines
1.8 KiB
Plaintext
73 lines
1.8 KiB
Plaintext
=pod
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=head1 NAME
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EVP_chacha20,
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EVP_chacha20_poly1305
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- EVP ChaCha20 stream cipher
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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const EVP_CIPHER *EVP_chacha20(void);
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const EVP_CIPHER *EVP_chacha20_poly1305(void);
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=head1 DESCRIPTION
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The ChaCha20 stream cipher for EVP.
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=over 4
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=item EVP_chacha20()
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The ChaCha20 stream cipher. The key length is 256 bits, the IV is 128 bits long.
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The first 32 bits consists of a counter in little-endian order followed by a 96
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bit nonce. For example a nonce of:
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000000000000000000000002
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With an initial counter of 42 (2a in hex) would be expressed as:
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2a000000000000000000000000000002
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=item EVP_chacha20_poly1305()
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Authenticated encryption with ChaCha20-Poly1305. Like EVP_chacha20(), the key
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is 256 bits and the IV is 96 bits. This supports additional authenticated data
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(AAD) and produces a 128-bit authentication tag. See the
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L<EVP_EncryptInit(3)/AEAD Interface> section for more information.
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=back
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=head1 NOTES
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Developers should be aware of the negative performance implications of
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calling these functions multiple times and should consider using
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L<EVP_CIPHER_fetch(3)> instead.
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See L<crypto(7)/Performance> for further information.
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=head1 RETURN VALUES
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These functions return an B<EVP_CIPHER> structure that contains the
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implementation of the symmetric cipher. See L<EVP_CIPHER_meth_new(3)> for
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details of the B<EVP_CIPHER> structure.
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=head1 SEE ALSO
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L<evp(7)>,
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L<EVP_EncryptInit(3)>,
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L<EVP_CIPHER_meth_new(3)>
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=head1 COPYRIGHT
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Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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