1X509_CMP(3)                         OpenSSL                        X509_CMP(3)
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NAME

6       X509_cmp, X509_NAME_cmp, X509_issuer_and_serial_cmp,
7       X509_issuer_name_cmp, X509_subject_name_cmp, X509_CRL_cmp,
8       X509_CRL_match - compare X509 certificates and related values
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SYNOPSIS

11        #include <openssl/x509.h>
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13        int X509_cmp(const X509 *a, const X509 *b);
14        int X509_NAME_cmp(const X509_NAME *a, const X509_NAME *b);
15        int X509_issuer_and_serial_cmp(const X509 *a, const X509 *b);
16        int X509_issuer_name_cmp(const X509 *a, const X509 *b);
17        int X509_subject_name_cmp(const X509 *a, const X509 *b);
18        int X509_CRL_cmp(const X509_CRL *a, const X509_CRL *b);
19        int X509_CRL_match(const X509_CRL *a, const X509_CRL *b);
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DESCRIPTION

22       This set of functions are used to compare X509 objects, including X509
23       certificates, X509 CRL objects and various values in an X509
24       certificate.
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26       The X509_cmp() function compares two X509 objects indicated by
27       parameters a and b. The comparison is based on the memcmp result of the
28       hash values of two X509 objects and the canonical (DER) encoding
29       values.
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31       The X509_NAME_cmp() function compares two X509_NAME objects indicated
32       by parameters a and b. The comparison is based on the memcmp result of
33       the canonical (DER) encoding values of the two objects.
34       i2d_X509_NAME(3) has a more detailed description of the DER encoding of
35       the X509_NAME structure.
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37       The X509_issuer_and_serial_cmp() function compares the serial number
38       and issuer values in the given X509 objects a and b.
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40       The X509_issuer_name_cmp(), X509_subject_name_cmp() and X509_CRL_cmp()
41       functions are effectively wrappers of the X509_NAME_cmp() function.
42       These functions compare issuer names and subject names of the  objects,
43       or issuers of X509_CRL objects, respectively.
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45       The X509_CRL_match() function compares two X509_CRL objects. Unlike the
46       X509_CRL_cmp() function, this function compares the whole CRL content
47       instead of just the issuer name.
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RETURN VALUES

50       Like common memory comparison functions, the X509 comparison functions
51       return an integer less than, equal to, or greater than zero if object a
52       is found to be less than, to match, or be greater than object b,
53       respectively.
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55       X509_NAME_cmp(), X509_issuer_and_serial_cmp(), X509_issuer_name_cmp(),
56       X509_subject_name_cmp() and X509_CRL_cmp() may return -2 to indicate an
57       error.
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NOTES

60       These functions in fact utilize the underlying memcmp of the C library
61       to do the comparison job. Data to be compared varies from DER encoding
62       data, hash value or ASN1_STRING. The sign of the comparison can be used
63       to order the objects but it does not have a special meaning in some
64       cases.
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66       X509_NAME_cmp() and wrappers utilize the value -2 to indicate errors in
67       some circumstances, which could cause confusion for the applications.
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SEE ALSO

70       i2d_X509_NAME(3), i2d_X509(3)
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73       Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
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75       Licensed under the Apache License 2.0 (the "License").  You may not use
76       this file except in compliance with the License.  You can obtain a copy
77       in the file LICENSE in the source distribution or at
78       <https://www.openssl.org/source/license.html>.
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821.1.1q                            2023-07-20                       X509_CMP(3)
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