| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | X509_cmp, X509_NAME_cmp,
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| 6 | X509_issuer_and_serial_cmp, X509_issuer_name_cmp, X509_subject_name_cmp,
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| 7 | X509_CRL_cmp, X509_CRL_match
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| 8 | - compare X509 certificates and related values
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| 9 |
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| 10 | =head1 SYNOPSIS
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| 11 |
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| 12 | #include <openssl/x509.h>
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| 13 |
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| 14 | int X509_cmp(const X509 *a, const X509 *b);
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| 15 | int X509_NAME_cmp(const X509_NAME *a, const X509_NAME *b);
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| 16 | int X509_issuer_and_serial_cmp(const X509 *a, const X509 *b);
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| 17 | int X509_issuer_name_cmp(const X509 *a, const X509 *b);
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| 18 | int X509_subject_name_cmp(const X509 *a, const X509 *b);
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| 19 | int X509_CRL_cmp(const X509_CRL *a, const X509_CRL *b);
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| 20 | int X509_CRL_match(const X509_CRL *a, const X509_CRL *b);
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| 21 |
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| 22 | =head1 DESCRIPTION
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| 23 |
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| 24 | This set of functions are used to compare X509 objects, including X509
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| 25 | certificates, X509 CRL objects and various values in an X509 certificate.
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| 26 |
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| 27 | The X509_cmp() function compares two B<X509> objects indicated by parameters
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| 28 | I<a> and I<b>. The comparison is based on the B<memcmp> result of the hash
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| 29 | values of two B<X509> objects and the canonical (DER) encoding values.
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| 30 |
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| 31 | The X509_NAME_cmp() function compares two B<X509_NAME> objects indicated by
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| 32 | parameters I<a> and I<b>. The comparison is based on the B<memcmp> result of the
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| 33 | canonical (DER) encoding values of the two objects using L<i2d_X509_NAME(3)>.
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| 34 | This procedure adheres to the matching rules for Distinguished Names (DN)
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| 35 | given in RFC 4517 section 4.2.15 and RFC 5280 section 7.1.
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| 36 | In particular, the order of Relative Distinguished Names (RDNs) is relevant.
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| 37 | On the other hand, if an RDN is multi-valued, i.e., it contains a set of
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| 38 | AttributeValueAssertions (AVAs), its members are effectively not ordered.
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| 39 |
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| 40 | The X509_issuer_and_serial_cmp() function compares the serial number and issuer
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| 41 | values in the given B<X509> objects I<a> and I<b>.
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| 42 |
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| 43 | The X509_issuer_name_cmp(), X509_subject_name_cmp() and X509_CRL_cmp() functions
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| 44 | are effectively wrappers of the X509_NAME_cmp() function. These functions compare
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| 45 | issuer names and subject names of the X<509> objects, or issuers of B<X509_CRL>
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| 46 | objects, respectively.
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| 47 |
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| 48 | The X509_CRL_match() function compares two B<X509_CRL> objects. Unlike the
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| 49 | X509_CRL_cmp() function, this function compares the whole CRL content instead
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| 50 | of just the issuer name.
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| 51 |
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| 52 | =head1 RETURN VALUES
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| 53 |
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| 54 | The B<X509> comparison functions return B<-1>, B<0>, or B<1> if object I<a> is
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| 55 | found to be less than, to match, or be greater than object I<b>, respectively.
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| 56 |
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| 57 | X509_NAME_cmp(), X509_issuer_and_serial_cmp(), X509_issuer_name_cmp(),
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| 58 | X509_subject_name_cmp(), X509_CRL_cmp(), and X509_CRL_match()
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| 59 | may return B<-2> to indicate an error.
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| 60 |
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| 61 | =head1 NOTES
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| 62 |
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| 63 | These functions in fact utilize the underlying B<memcmp> of the C library to do
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| 64 | the comparison job. Data to be compared varies from DER encoding data, hash
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| 65 | value or B<ASN1_STRING>. The sign of the comparison can be used to order the
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| 66 | objects but it does not have a special meaning in some cases.
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| 67 |
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| 68 | X509_NAME_cmp() and wrappers utilize the value B<-2> to indicate errors in some
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| 69 | circumstances, which could cause confusion for the applications.
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| 70 |
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| 71 | =head1 SEE ALSO
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| 72 |
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| 73 | L<i2d_X509_NAME(3)>, L<i2d_X509(3)>
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| 74 |
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| 75 | =head1 COPYRIGHT
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| 76 |
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| 77 | Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
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| 78 |
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| 79 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 80 | this file except in compliance with the License. You can obtain a copy
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| 81 | in the file LICENSE in the source distribution or at
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| 82 | L<https://www.openssl.org/source/license.html>.
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| 83 |
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| 84 | =cut
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