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.\" ========================================================================
.\"
.IX Title "X509_CHECK_PURPOSE 3ossl"
.TH X509_CHECK_PURPOSE 3ossl "2023-09-19" "3.0.11" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
X509_check_purpose \- Check the purpose of a certificate
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/x509v3.h>
\&
\& int X509_check_purpose(X509 *x, int id, int ca);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This function 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 \s-1CA\s0 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 \s-1ID\s0's that can be checked:
.PP
.Vb 9
\& # 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
.Ve
.PP
The checks performed take into account the X.509 extensions
keyUsage, extendedKeyUsage, and basicConstraints.
.SH "RETURN VALUES"
.IX Header "RETURN 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 \s-1CA\s0 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 \s-1CA\s0 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 \s-1CA.\s0" 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 \s-1CA\s0" 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 \s-1CA\s0 Flags present" 4
.IX Item " 5 legacy Netscape specific CA Flags present"
.PD
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2019\-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this
file except in compliance with the License. You can obtain a copy in the file
\&\s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.