xref: /openssl/doc/man3/X509_digest.pod (revision fecb3aae) 
1=pod
2
3=head1 NAME
4
5X509_digest,
6X509_digest_sig,
7X509_CRL_digest,
8X509_pubkey_digest,
9X509_NAME_digest,
10X509_REQ_digest,
11PKCS7_ISSUER_AND_SERIAL_digest
12- get digest of various objects
13
14=head1 SYNOPSIS
15
16 #include <openssl/x509.h>
17
18 int X509_digest(const X509 *data, const EVP_MD *type, unsigned char *md,
19                 unsigned int *len);
20 ASN1_OCTET_STRING *X509_digest_sig(const X509 *cert,
21                                    EVP_MD **md_used, int *md_is_fallback);
22
23 int X509_CRL_digest(const X509_CRL *data, const EVP_MD *type, unsigned char *md,
24                     unsigned int *len);
25
26 int X509_pubkey_digest(const X509 *data, const EVP_MD *type,
27                        unsigned char *md, unsigned int *len);
28
29 int X509_REQ_digest(const X509_REQ *data, const EVP_MD *type,
30                     unsigned char *md, unsigned int *len);
31
32 int X509_NAME_digest(const X509_NAME *data, const EVP_MD *type,
33                      unsigned char *md, unsigned int *len);
34
35 #include <openssl/pkcs7.h>
36
37 int PKCS7_ISSUER_AND_SERIAL_digest(PKCS7_ISSUER_AND_SERIAL *data,
38                                    const EVP_MD *type, unsigned char *md,
39                                    unsigned int *len);
40
41=head1 DESCRIPTION
42
43X509_digest_sig() calculates a digest of the given certificate I<cert>
44using the same hash algorithm as in its signature, if the digest
45is an integral part of the certificate signature algorithm identifier.
46Otherwise, a fallback hash algorithm is determined as follows:
47SHA512 if the signature algorithm is ED25519,
48SHAKE256 if it is ED448, otherwise SHA256.
49The output parameters are assigned as follows.
50Unless I<md_used> is NULL, the hash algorithm used is provided
51in I<*md_used> and must be freed by the caller (if it is not NULL).
52Unless I<md_is_fallback> is NULL,
53the I<*md_is_fallback> is set to 1 if the hash algorithm used is a fallback,
54otherwise to 0.
55
56X509_pubkey_digest() returns a digest of the DER representation of the public
57key in the specified X509 I<data> object.
58
59All other functions described here return a digest of the DER representation
60of their entire I<data> objects.
61
62The I<type> parameter specifies the digest to
63be used, such as EVP_sha1(). The I<md> is a pointer to the buffer where the
64digest will be copied and is assumed to be large enough; the constant
65B<EVP_MAX_MD_SIZE> is suggested. The I<len> parameter, if not NULL, points
66to a place where the digest size will be stored.
67
68=head1 RETURN VALUES
69
70X509_digest_sig() returns an ASN1_OCTET_STRING pointer on success, else NULL.
71
72All other functions described here return 1 for success and 0 for failure.
73
74=head1 SEE ALSO
75
76L<EVP_sha1(3)>
77
78=head1 HISTORY
79
80The X509_digest_sig() function was added in OpenSSL 3.0.
81
82=head1 COPYRIGHT
83
84Copyright 2017-2022 The OpenSSL Project Authors. All Rights Reserved.
85
86Licensed under the Apache License 2.0 (the "License").  You may not use
87this file except in compliance with the License.  You can obtain a copy
88in the file LICENSE in the source distribution or at
89L<https://www.openssl.org/source/license.html>.
90
91=cut
92