1=pod
2
3=head1 NAME
4
5EVP_PKEY_get_default_digest_nid, EVP_PKEY_get_default_digest_name
6- get default signature digest
7
8=head1 SYNOPSIS
9
10 #include <openssl/evp.h>
11
12 int EVP_PKEY_get_default_digest_name(EVP_PKEY *pkey,
13                                      char *mdname, size_t mdname_sz);
14 int EVP_PKEY_get_default_digest_nid(EVP_PKEY *pkey, int *pnid);
15
16=head1 DESCRIPTION
17
18EVP_PKEY_get_default_digest_name() fills in the default message digest
19name for the public key signature operations associated with key
20I<pkey> into I<mdname>, up to at most I<mdname_sz> bytes including the
21ending NUL byte.  The name could be C<"UNDEF">, signifying that a digest
22must (for return value 2) or may (for return value 1) be left unspecified.
23
24EVP_PKEY_get_default_digest_nid() sets I<pnid> to the default message
25digest NID for the public key signature operations associated with key
26I<pkey>.  Note that some signature algorithms (i.e. Ed25519 and Ed448)
27do not use a digest during signing.  In this case I<pnid> will be set
28to NID_undef.  This function is only reliable for legacy keys, which
29are keys with a B<EVP_PKEY_ASN1_METHOD>; these keys have typically
30been loaded from engines, or created with L<EVP_PKEY_assign_RSA(3)> or
31similar.
32
33=head1 NOTES
34
35For all current standard OpenSSL public key algorithms SHA256 is returned.
36
37=head1 RETURN VALUES
38
39EVP_PKEY_get_default_digest_name() and EVP_PKEY_get_default_digest_nid()
40both return 1 if the message digest is advisory (that is other digests
41can be used) and 2 if it is mandatory (other digests can not be used).
42They return 0 or a negative value for failure.  In particular a return
43value of -2 indicates the operation is not supported by the public key
44algorithm.
45
46=head1 SEE ALSO
47
48L<EVP_PKEY_CTX_new(3)>,
49L<EVP_PKEY_sign(3)>,
50L<EVP_PKEY_digestsign_supports_digest(3)>,
51L<EVP_PKEY_verify(3)>,
52L<EVP_PKEY_verify_recover(3)>,
53
54=head1 HISTORY
55
56This function was added in OpenSSL 1.0.0.
57
58=head1 COPYRIGHT
59
60Copyright 2006-2023 The OpenSSL Project Authors. All Rights Reserved.
61
62Licensed under the Apache License 2.0 (the "License").  You may not use
63this file except in compliance with the License.  You can obtain a copy
64in the file LICENSE in the source distribution or at
65L<https://www.openssl.org/source/license.html>.
66
67=cut
68