=pod
{- OpenSSL::safe::output_do_not_edit_headers(); -}

=head1 NAME

openssl-verify - certificate verification command

=head1 SYNOPSIS

B<openssl> B<verify>
[B<-help>]
[B<-CRLfile> I<file>]
[B<-crl_download>]
[B<-show_chain>]
[B<-verbose>]
[B<-trusted> I<file>]
[B<-untrusted> I<file>]
[B<-vfyopt> I<nm>:I<v>]
{- $OpenSSL::safe::opt_name_synopsis -}
{- $OpenSSL::safe::opt_trust_synopsis -}
{- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_v_synopsis -}
{- $OpenSSL::safe::opt_provider_synopsis -}
[B<-->]
[I<certificate> ...]

=head1 DESCRIPTION

This command verifies certificate chains. If a certificate chain has multiple
problems, this program attempts to display all of them.

=head1 OPTIONS

=over 4

=item B<-help>

Print out a usage message.

=item B<-CRLfile> I<file>

The file or URI should contain one or more CRLs in PEM or DER format.
This option can be specified more than once to include CRLs from multiple
I<file>s.

=item B<-crl_download>

Attempt to download CRL information for certificates via their CDP entries.

=item B<-show_chain>

Display information about the certificate chain that has been built (if
successful). Certificates in the chain that came from the untrusted list will be
flagged as "untrusted".

=item B<-verbose>

Print extra information about the operations being performed.

=item B<-trusted> I<file>

A file or URI of trusted certificates in PEM, DER, or PKCS#12 format.
This option can be specified more than once to load certificates from multiple
I<file>s.

=item B<-untrusted> I<file>

A file or URI of untrusted certificates in PEM, DER, or PKCS#12 format
to use for chain building.
This option can be specified more than once to load certificates from multiple
I<file>s.


=item B<-vfyopt> I<nm>:I<v>

Pass options to the signature algorithm during verify operations.
Names and values of these options are algorithm-specific.

{- $OpenSSL::safe::opt_name_item -}

{- $OpenSSL::safe::opt_engine_item -}
{- output_off() if $disabled{"deprecated-3.0"}; "" -}
To load certificates or CRLs that require engine support, specify the
B<-engine> option before any of the
B<-trusted>, B<-untrusted> or B<-CRLfile> options.
{- output_on() if $disabled{"deprecated-3.0"}; "" -}

{- $OpenSSL::safe::opt_trust_item -}

{- $OpenSSL::safe::opt_v_item -}

{- $OpenSSL::safe::opt_provider_item -}

=item B<-->

Indicates the last option. All arguments following this are assumed to be
certificate files. This is useful if the first certificate filename begins
with a B<->.

=item I<certificate> ...

One or more target certificates to verify, one per file. If no certificates are
given, this command will attempt to read a single certificate from standard
input.

=back

=head1 DIAGNOSTICS

When a verify operation fails the output messages can be somewhat cryptic. The
general form of the error message is:

 server.pem: /C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test CA (1024 bit)
 error 24 at 1 depth lookup:invalid CA certificate

The first line contains the name of the certificate being verified followed by
the subject name of the certificate. The second line contains the error number
and the depth. The depth is number of the certificate being verified when a
problem was detected starting with zero for the target ("leaf") certificate
itself then 1 for the CA that signed the target certificate and so on.
Finally a textual version of the error number is presented.

A list of the error codes and messages can be found in
L<X509_STORE_CTX_get_error(3)>; the full list is defined in the header file
F<< <openssl/x509_vfy.h> >>.

This command ignores many errors, in order to allow all the problems with a
certificate chain to be determined.

=head1 BUGS

Although the issuer checks are a considerable improvement over the old
technique they still suffer from limitations in the underlying X509_LOOKUP
API. One consequence of this is that trusted certificates with matching
subject name must either appear in a file (as specified by the B<-CAfile>
option), a directory (as specified by B<-CApath>), or a store (as specified
by B<-CAstore>). If they occur in more than one location then only the
certificates in the file will be recognised.

Previous versions of OpenSSL assume certificates with matching subject
name are identical and mishandled them.

Previous versions of this documentation swapped the meaning of the
B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT> and
B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY> error codes.

=head1 SEE ALSO

L<openssl-verification-options(1)>,
L<openssl-x509(1)>,
L<ossl_store-file(7)>

=head1 HISTORY

The B<-show_chain> option was added in OpenSSL 1.1.0.

The B<-engine option> was deprecated in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2000-2021 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
L<https://www.openssl.org/source/license.html>.

=cut