=pod

=head1 NAME

evp_keymgmt_export_to_provider,
evp_keymgmt_clear_pkey_cache
- key material provider export for EVP

=head1 SYNOPSIS

 #include "crypto/evp.h"

 void *evp_keymgmt_export_to_provider(EVP_PKEY *pk, EVP_KEYMGMT *keymgmt);
 void evp_keymgmt_clear_pkey_cache(EVP_PKEY *pk);

=head1 DESCRIPTION

evp_keymgmt_export_to_provider() exports the key material from the
given key I<pk> to a provider via a B<EVP_KEYMGMT> interface, if this
hasn't already been done.
It maintains a cache of provider key references in I<pk> to keep track
of all such exports.

If I<pk> has an assigned legacy key, a check is done to see if any of
its key material has changed since last export, i.e. the legacy key's
is_dirty() method returns 1.
If it has, the cache of already exported keys is cleared, and a new
export is made with the new key material.

evp_keymgmt_clear_pkey_cache() can be used to explicitly clear the
cache of provider key references.

=head1 RETURN VALUES

evp_keymgmt_export_to_provider() returns a pointer to the appropriate
provider side key (created or found again), or NULL on error.

=head1 NOTES

"Legacy key" is the term used for any key that has been assigned to an
B<EVP_PKEY> with EVP_PKEY_assign_RSA() and similar functions.

=head1 SEE ALSO

L<EVP_PKEY_ASN1_METHOD(3)>, L<EVP_PKEY_assign_RSA(3)>

=head1 COPYRIGHT

Copyright 2019 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>.

=cut
