.\" -*- mode: troff; coding: utf-8 -*- .\" Automatically generated by Pod::Man 5.0102 (Pod::Simple 3.45) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. .ie n \{\ . ds C` "" . ds C' "" 'br\} .el\{\ . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" ======================================================================== .\" .IX Title "X509_CHECK_PURPOSE 3ssl" .TH X509_CHECK_PURPOSE 3ssl 2025-07-01 3.5.1 OpenSSL .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH NAME X509_check_purpose, X509_PURPOSE_get_count, X509_PURPOSE_get_unused_id, X509_PURPOSE_get_by_sname, X509_PURPOSE_get_by_id, X509_PURPOSE_add, X509_PURPOSE_cleanup, X509_PURPOSE_get0, X509_PURPOSE_get_id, X509_PURPOSE_get0_name, X509_PURPOSE_get0_sname, X509_PURPOSE_get_trust, X509_PURPOSE_set \- functions related to checking the purpose of a certificate .SH SYNOPSIS .IX Header "SYNOPSIS" .Vb 1 \& #include \& \& int X509_check_purpose(X509 *x, int id, int ca); \& \& int X509_PURPOSE_get_count(void); \& int X509_PURPOSE_get_unused_id(OSSL_LIB_CTX *libctx); \& int X509_PURPOSE_get_by_sname(const char *sname); \& int X509_PURPOSE_get_by_id(int id); \& int X509_PURPOSE_add(int id, int trust, int flags, \& int (*ck) (const X509_PURPOSE *, const X509 *, int), \& const char *name, const char *sname, void *arg); \& void X509_PURPOSE_cleanup(void); \& \& X509_PURPOSE *X509_PURPOSE_get0(int idx); \& int X509_PURPOSE_get_id(const X509_PURPOSE *); \& char *X509_PURPOSE_get0_name(const X509_PURPOSE *xp); \& char *X509_PURPOSE_get0_sname(const X509_PURPOSE *xp); \& int X509_PURPOSE_get_trust(const X509_PURPOSE *xp); \& int X509_PURPOSE_set(int *p, int purpose); .Ve .SH DESCRIPTION .IX Header "DESCRIPTION" \&\fBX509_check_purpose()\fR checks if certificate \fIx\fR was created with the purpose represented by \fIid\fR. If \fIca\fR is nonzero, then certificate \fIx\fR is checked to determine if it's a possible CA with various levels of certainty possibly returned. The certificate \fIx\fR must be a complete certificate otherwise the function returns an error. .PP Below are the potential ID's that can be checked: .PP .Vb 10 \& # define X509_PURPOSE_SSL_CLIENT 1 \& # define X509_PURPOSE_SSL_SERVER 2 \& # define X509_PURPOSE_NS_SSL_SERVER 3 \& # define X509_PURPOSE_SMIME_SIGN 4 \& # define X509_PURPOSE_SMIME_ENCRYPT 5 \& # define X509_PURPOSE_CRL_SIGN 6 \& # define X509_PURPOSE_ANY 7 \& # define X509_PURPOSE_OCSP_HELPER 8 \& # define X509_PURPOSE_TIMESTAMP_SIGN 9 \& # define X509_PURPOSE_CODE_SIGN 10 .Ve .PP The checks performed take into account the X.509 extensions keyUsage, extendedKeyUsage, and basicConstraints. .PP \&\fBX509_PURPOSE_get_count()\fR returns the number of currently defined purposes. .PP \&\fBX509_PURPOSE_get_unused_id()\fR returns the smallest purpose id not yet used, which is guaranteed to be unique and larger than \fBX509_PURPOSE_MAX\fR. The \fIlibctx\fR parameter should be used to provide the library context. It is currently ignored as the purpose mapping table is global. .PP \&\fBX509_PURPOSE_get_by_sname()\fR returns the index of the purpose with the given short name or \-1 if not found. .PP \&\fBX509_PURPOSE_get_by_id()\fR returns the index of the purpose with the given id or \-1 if not found. .PP \&\fBX509_PURPOSE_add()\fR adds or modifies a purpose entry identified by \fIsname\fR. Unless the id stays the same for an existing entry, \fIid\fR must be fresh, which can be achieved by using the result of \fBX509_PURPOSE_get_unused_id()\fR. The function also sets in the entry the trust id \fItrust\fR, the given \fIflags\fR, the purpose (long) name \fIname\fR, the short name \fIsname\fR, the purpose checking function \fIck\fR of type \fBint (*) (const X509_PURPOSE *, const X509 *, int)\fR, and its user data \fIarg\fR which may be retrieved via the \fBX509_PURPOSE\fR pointer. .PP \&\fBX509_PURPOSE_cleanup()\fR removes all purposes that are not pre-defined. .PP \&\fBX509_PURPOSE_get0()\fR returns an \fBX509_PURPOSE\fR pointer or NULL on error. .PP \&\fBX509_PURPOSE_get_id()\fR returns the id of the given \fBX509_PURPOSE\fR structure. .PP \&\fBX509_PURPOSE_get0_name()\fR returns the (long) name of the given \fBX509_PURPOSE\fR. .PP \&\fBX509_PURPOSE_get0_sname()\fR returns the short name of the given \fBX509_PURPOSE\fR. .PP \&\fBX509_PURPOSE_get_trust()\fR returns the trust id of the given \fBX509_PURPOSE\fR. .PP \&\fBX509_PURPOSE_set()\fR assigns the given \fIpurpose\fR id to the location pointed at by \&\fIp\fR. This resets to the any purpose if \fIpurpose\fR is \fBX509_PURPOSE_DEFAULT_ANY\fR. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBX509_check_purpose()\fR returns the following values. For non-CA checks .IP "\-1 an error condition has occurred" 4 .IX Item "-1 an error condition has occurred" .PD 0 .IP " 1 if the certificate was created to perform the purpose represented by \fIid\fR" 4 .IX Item " 1 if the certificate was created to perform the purpose represented by id" .IP " 0 if the certificate was not created to perform the purpose represented by \fIid\fR" 4 .IX Item " 0 if the certificate was not created to perform the purpose represented by id" .PD .PP For CA checks the below integers could be returned with the following meanings: .IP "\-1 an error condition has occurred" 4 .IX Item "-1 an error condition has occurred" .PD 0 .IP " 0 not a CA or does not have the purpose represented by \fIid\fR" 4 .IX Item " 0 not a CA or does not have the purpose represented by id" .IP " 1 is a CA." 4 .IX Item " 1 is a CA." .IP " 2 Only possible in old versions of openSSL when basicConstraints are absent. New versions will not return this value. May be a CA" 4 .IX Item " 2 Only possible in old versions of openSSL when basicConstraints are absent. New versions will not return this value. May be a CA" .IP " 3 basicConstraints absent but self signed V1." 4 .IX Item " 3 basicConstraints absent but self signed V1." .IP " 4 basicConstraints absent but keyUsage present and keyCertSign asserted." 4 .IX Item " 4 basicConstraints absent but keyUsage present and keyCertSign asserted." .IP " 5 legacy Netscape specific CA Flags present" 4 .IX Item " 5 legacy Netscape specific CA Flags present" .PD .PP \&\fBX509_PURPOSE_get_count()\fR returns the number of currently defined purposes. .PP \&\fBX509_PURPOSE_get_unused_id()\fR returns the smallest purpose id not yet used. .PP \&\fBX509_PURPOSE_get_by_sname()\fR returns the index of the purpose with the given short name or \-1 if not found. .PP \&\fBX509_PURPOSE_get_by_id()\fR returns the index of the purpose with the given id or \-1 if not found. .PP int \fBX509_PURPOSE_add()\fR returns 1 on success, 0 on error. .PP \&\fBX509_PURPOSE_cleanup()\fR does not return anything. .PP \&\fBX509_PURPOSE_get0()\fR returns an \fBX509_PURPOSE\fR pointer or NULL on error. .PP \&\fBX509_PURPOSE_get_id()\fR returns the id of the given \fBX509_PURPOSE\fR structure. .PP \&\fBX509_PURPOSE_get0_name()\fR returns the (long) name of the given \fBX509_PURPOSE\fR. .PP \&\fBX509_PURPOSE_get0_sname()\fR returns the short name of the given \fBX509_PURPOSE\fR. .PP \&\fBX509_PURPOSE_get_trust()\fR returns the trust id of the given \fBX509_PURPOSE\fR. .PP \&\fBX509_PURPOSE_set()\fR returns 1 on success, 0 on error. .SH BUGS .IX Header "BUGS" The X509_PURPOSE implementation so far is not thread-safe. There may be race conditions retrieving purpose information while \&\fBX509_PURPOSE_add()\fR or X509_PURPOSE_cleanup(void) is being called. .SH HISTORY .IX Header "HISTORY" \&\fBX509_PURPOSE_get_unused_id()\fR was added in OpensSL 3.5. .SH COPYRIGHT .IX Header "COPYRIGHT" Copyright 2019\-2025 The OpenSSL Project Authors. All Rights Reserved. Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at .