1=pod
2
3=head1 NAME
4
5evp_pkey_export_to_provider, evp_pkey_copy_downgraded, evp_pkey_get_legacy
6- internal EVP_PKEY support functions for providers
7
8=head1 SYNOPSIS
9
10 /* Only for EVP source */
11 #include "evp_local.h"
12
13 void *evp_pkey_export_to_provider(EVP_PKEY *pk, OSSL_LIB_CTX *libctx,
14                                   EVP_KEYMGMT **keymgmt,
15                                   const char *propquery);
16 int evp_pkey_copy_downgraded(EVP_PKEY **dest, const EVP_PKEY *src);
17 void *evp_pkey_get_legacy(EVP_PKEY *pk);
18
19=head1 DESCRIPTION
20
21This manual uses the term "origin", which is explained in internal
22L<EVP_PKEY(7)>.
23
24evp_pkey_export_to_provider() exports the "origin" key contained in I<pk>
25to its operation cache to make it suitable for an B<EVP_KEYMGMT> given either
26with I<*keymgmt> or with an implicit fetch using I<libctx> (NULL means the
27default context), the name of the legacy type of I<pk>, and the I<propquery>
28(NULL means the default property query settings).
29
30If I<keymgmt> isn't NULL but I<*keymgmt> is, and the "origin" was successfully
31exported, then I<*keymgmt> is assigned the implicitly fetched B<EVP_KEYMGMT>.
32
33evp_pkey_copy_downgraded() makes a copy of I<src> in legacy form into I<*dest>,
34if there's a corresponding legacy implementation.  This should be used if the
35use of a downgraded key is temporary.
36For example, L<PEM_write_bio_PrivateKey_traditional(3)> uses this to try its
37best to get "traditional" PEM output even if the input B<EVP_PKEY> has a
38provider-native internal key.
39
40evp_pkey_get_legacy() obtains and returns a legacy key structure. If the
41EVP_PKEY already contains a legacy key then it is simply returned. If it is a
42provider based key, then a new legacy key is constructed based on the provider
43key. The legacy key is cached inside the EVP_PKEY and its value returned from
44this function. Subsequent calls to evp_pkey_get_legacy() will return the cached
45key. Subsequent changes to the provider key are not reflected back in the
46legacy key. Similarly changes to the legacy key are not reflected back in the
47provider key.
48
49=head1 RETURN VALUES
50
51evp_pkey_export_to_provider() returns the provider key data if there was any
52allocated.  It also either sets I<*keymgmt> to the B<EVP_KEYMGMT> associated
53with the returned key data, or NULL on error.
54
55evp_pkey_get_legacy() returns the legacy key or NULL on error.
56
57=head1 NOTES
58
59Some functions calling evp_pkey_export_to_provider() may have received a const
60key, and may therefore have to cast the key to non-const form to call this
61function.  Since B<EVP_PKEY> is always dynamically allocated, this is OK.
62
63=head1 SEE ALSO
64
65L<OSSL_LIB_CTX(3)>, L<EVP_KEYMGMT(3)>
66
67=head1 HISTORY
68
69The functions described here were all added in OpenSSL 3.0.
70
71=head1 COPYRIGHT
72
73Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
74
75Licensed under the Apache License 2.0 (the "License").  You may not use
76this file except in compliance with the License.  You can obtain a copy
77in the file LICENSE in the source distribution or at
78L<https://www.openssl.org/source/license.html>.
79
80=cut
81