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.\" ========================================================================
.\"
.IX Title "X509_verify_cert 3"
.TH X509_verify_cert 3 2019-12-20 1.0.2u OpenSSL
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH NAME
X509_verify_cert \- discover and verify X509 certificte chain
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/x509.h>
\&
\& int X509_verify_cert(X509_STORE_CTX *ctx);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
The \fBX509_verify_cert()\fR function attempts to discover and validate a
certificate chain based on parameters in \fBctx\fR. A complete description of
the process is contained in the \fBverify\fR\|(1) manual page.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
If a complete chain can be built and validated this function returns 1,
otherwise it return zero, in exceptional circumstances it can also
return a negative code.
.PP
If the function fails additional error information can be obtained by
examining \fBctx\fR using, for example \fBX509_STORE_CTX_get_error()\fR.
.SH NOTES
.IX Header "NOTES"
Applications rarely call this function directly but it is used by
OpenSSL internally for certificate validation, in both the S/MIME and
SSL/TLS code.
.PP
A negative return value from \fBX509_verify_cert()\fR can occur if it is invoked
incorrectly, such as with no certificate set in \fBctx\fR, or when it is called
twice in succession without reinitialising \fBctx\fR for the second call.
A negative return value can also happen due to internal resource problems or if
a retry operation is requested during internal lookups (which never happens
with standard lookup methods).
Applications must check for <= 0 return value on error.
.SH BUGS
.IX Header "BUGS"
This function uses the header \fBx509.h\fR as opposed to most chain verification
functiosn which use \fBx509_vfy.h\fR.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBX509_STORE_CTX_get_error\fR\|(3)
.SH HISTORY
.IX Header "HISTORY"
\&\fBX509_verify_cert()\fR is available in all versions of SSLeay and OpenSSL.