openssl/doc/man3/EVP_CIPHER_CTX_get_iv.pod

=pod

=head1 NAME

EVP_CIPHER_CTX_get_iv, EVP_CIPHER_CTX_get_iv_state, EVP_CIPHER_CTX_iv, EVP_CIPHER_CTX_original_iv, EVP_CIPHER_CTX_iv_noconst - Routines to inspect EVP_CIPHER_CTX IV data

=head1 SYNOPSIS

 #include <openssl/evp.h>

 int EVP_CIPHER_CTX_get_iv(EVP_CIPHER_CTX *ctx, void *buf, size_t len);
 int EVP_CIPHER_CTX_get_iv_state(EVP_CIPHER_CTX *ctx, void *buf, size_t len);
 const unsigned char *EVP_CIPHER_CTX_iv(const EVP_CIPHER_CTX *ctx);
 const unsigned char *EVP_CIPHER_CTX_original_iv(const EVP_CIPHER_CTX *ctx);
 unsigned char *EVP_CIPHER_CTX_iv_noconst(EVP_CIPHER_CTX *ctx);

=head1 DESCRIPTION

EVP_CIPHER_CTX_get_iv() and EVP_CIPHER_CTX_get_iv_state() copy initialization
vector (IV) information from the B<EVP_CIPHER_CTX> into the caller-supplied
buffer.  L<EVP_CIPHER_CTX_iv_length(3)> can be used to determine an
appropriate buffer size, and if the supplied buffer is too small, an error
will be returned (and no data copied).  EVP_CIPHER_CTX_get_iv() accesses the
("original") IV that was supplied when the B<EVP_CIPHER_CTX> was created, and
EVP_CIPHER_CTX_get_iv_state() accesses the current "IV state" of the cipher,
which is updated during cipher operation for certain cipher modes (e.g., CBC
and OFB).

The functions EVP_CIPHER_CTX_iv(), EVP_CIPHER_CTX_original_iv(), and
EVP_CIPHER_CTX_iv_noconst() are deprecated functions that provide similar (at
a conceptual level) functionality.  EVP_CIPHER_CTX_iv() returns a pointer to
the beginning of the "IV state" as maintained internally in the
B<EVP_CIPHER_CTX>; EVP_CIPHER_CTX_original_iv() returns a pointer to the
beginning of the ("original") IV, as maintained by the B<EVP_CIPHER_CTX>, that
was provided when the B<EVP_CIPHER_CTX> was initialized; and
EVP_CIPHER_CTX_get_iv_noconst() is the same as EVP_CIPHER_CTX_iv() but has a
different return type for the pointer.

=head1 RETURN VALUES

EVP_CIPHER_CTX_get_iv() and EVP_CIPHER_CTX_get_iv_state() return 1 on success
and 0 on failure.

The functions EVP_CIPHER_CTX_iv(), EVP_CIPHER_CTX_original_iv(), and
EVP_CIPHER_CTX_iv_noconst() return a pointer to an IV as an array of bytes on
success, and NULL on failure.

=head1 HISTORY

EVP_CIPHER_CTX_get_iv() and EVP_CIPHER_CTX_get_iv_state() were added in
OpenSSL 3.0.0.

EVP_CIPHER_CTX_iv(), EVP_CIPHER_CTX_original_iv(), and
EVP_CIPHER_CTX_iv_noconst() were added in OpenSSL 1.1.0, and were deprecated
in OpenSSL 3.0.0.

=head1 COPYRIGHT

Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (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
L<https://www.openssl.org/source/license.html>.

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