=pod

=head1 NAME

EVP_PKEY_check, EVP_PKEY_param_check, EVP_PKEY_param_check_quick,
EVP_PKEY_public_check, EVP_PKEY_public_check_quick, EVP_PKEY_private_check,
EVP_PKEY_pairwise_check
- key and parameter validation functions

=head1 SYNOPSIS

 #include <openssl/evp.h>

 int EVP_PKEY_check(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_param_check(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_param_check_quick(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_public_check(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_public_check_quick(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_private_check(EVP_PKEY_CTX *ctx);
 int EVP_PKEY_pairwise_check(EVP_PKEY_CTX *ctx);

=head1 DESCRIPTION

EVP_PKEY_param_check() validates the parameters component of the key
given by B<ctx>. This check will always succeed for key types that do not have
parameters.

EVP_PKEY_param_check_quick() validates the parameters component of the key
given by B<ctx> like EVP_PKEY_param_check() does. However some algorithm
implementations may offer a quicker form of validation that omits some checks in
order to perform a lightweight sanity check of the key. If a quicker form is not
provided then this function call does the same thing as EVP_PKEY_param_check().

EVP_PKEY_public_check() validates the public component of the key given by B<ctx>.

EVP_PKEY_public_check_quick() validates the public component of the key
given by B<ctx> like EVP_PKEY_public_check() does. However some algorithm
implementations may offer a quicker form of validation that omits some checks in
order to perform a lightweight sanity check of the key. If a quicker form is not
provided then this function call does the same thing as EVP_PKEY_public_check().

EVP_PKEY_private_check() validates the private component of the key given by B<ctx>.

EVP_PKEY_pairwise_check() validates that the public and private components have
the correct mathematical relationship to each other for the key given by B<ctx>.

EVP_PKEY_check() is an alias for the EVP_PKEY_pairwise_check() function.

=head1 NOTES

Key validation used by the OpenSSL FIPS provider complies with the rules
within SP800-56A and SP800-56B. For backwards compatibility reasons the OpenSSL
default provider may use checks that are not as restrictive for certain key types.
For further information see L<EVP_PKEY-DSA(7)/DSA key validation>,
L<EVP_PKEY-DH(7)/DH key validation>, L<EVP_PKEY-EC(7)/EC key validation> and
L<EVP_PKEY-RSA(7)/RSA key validation>.

Refer to SP800-56A and SP800-56B for rules relating to when these functions
should be called during key establishment.
It is not necessary to call these functions after locally calling an approved key
generation method, but may be required for assurance purposes when receiving
keys from a third party.

The EVP_PKEY_pairwise_check() and EVP_PKEY_private_check() might not be bounded
by any key size limits as private keys are not expected to be supplied by
attackers. For that reason they might take an unbounded time if run on
arbitrarily large keys.

=head1 RETURN VALUES

All functions return 1 for success or others for failure.
They return -2 if the operation is not supported for the specific algorithm.

=head1 SEE ALSO

L<EVP_PKEY_CTX_new(3)>,
L<EVP_PKEY_fromdata(3)>,
L<EVP_PKEY-DH(7)>,
L<EVP_PKEY-FFC(7)>,
L<EVP_PKEY-DSA(7)>,
L<EVP_PKEY-EC(7)>,
L<EVP_PKEY-RSA(7)>,

=head1 HISTORY

EVP_PKEY_check(), EVP_PKEY_public_check() and EVP_PKEY_param_check() were added
in OpenSSL 1.1.1.

EVP_PKEY_param_check_quick(), EVP_PKEY_public_check_quick(),
EVP_PKEY_private_check() and EVP_PKEY_pairwise_check() were added in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2006-2024 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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