=head1 NAME
-pkcs7 - PKCS#7 utility
+verify - Utility to verify certificates.
=head1 SYNOPSIS
[B<-purpose purpose>]
[B<-untrusted file>]
[B<-help>]
+[B<-issuer_checks>]
[B<-verbose>]
[B<->]
[certificates]
print extra information about the operations being performed.
+=item B<-issuer_checks>
+
+print out diagnostics relating to searches for the issuer certificate
+of the current certificate. This shows why each candidate issuer
+certificate was rejected. However the presence of rejection messages
+does not itself imply that anything is wrong: during the normal
+verify process several rejections may take place.
+
+=item B<-check_ss_sig>
+
+Verify the signature on the self-signed root CA. This is disabled by default
+because it doesn't add any security.
+
=item B<->
marks the last option. All arguments following this are assumed to be
Firstly a certificate chain is built up starting from the supplied certificate
and ending in the root CA. It is an error if the whole chain cannot be built
-up. The chain is built up by looking up a certificate whose subject name
-matches the issuer name of the current certificate. If a certificate is found
-whose subject and issuer names are identical it is assumed to be the root CA.
+up. The chain is built up by looking up the issuers certificate of the current
+certificate. If a certificate is found which is its own issuer it is assumed
+to be the root CA.
+
+The process of 'looking up the issuers certificate' itself involves a number
+of steps. In versions of OpenSSL before 0.9.5a the first certificate whose
+subject name matched the issuer of the current certificate was assumed to be
+the issuers certificate. In OpenSSL 0.9.6 and later all certificates
+whose subject name matches the issuer name of the current certificate are
+subject to further tests. The relevant authority key identifier components
+of the current certificate (if present) must match the subject key identifier
+(if present) and issuer and serial number of the candidate issuer, in addition
+the keyUsage extension of the candidate issuer (if present) must permit
+certificate signing.
+
The lookup first looks in the list of untrusted certificates and if no match
is found the remaining lookups are from the trusted certificates. The root CA
is always looked up in the trusted certificate list: if the certificate to
=item B<2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate>
-the issuer certificate could not be found: this occurs if the issuer certificate
-of an untrusted certificate cannot be found.
+the issuer certificate of a looked up certificate could not be found. This
+normally means the list of trusted certificates is not complete.
-=item B<3 X509_V_ERR_UNABLE_TO_GET_CRL unable to get certificate CRL>
+=item B<3 X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL>
the CRL of a certificate could not be found. Unused.
the certificate is not yet valid: the notBefore date is after the current time.
-=item B<10 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid>
+=item B<10 X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired>
-the CRL is not yet valid. Unused.
+the certificate has expired: that is the notAfter date is before the current time.
-=item B<11 X509_V_ERR_CERT_HAS_EXPIRED: Certificate has expired>
+=item B<11 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid>
-the certificate has expired: that is the notAfter date is before the current time.
+the CRL is not yet valid. Unused.
=item B<12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired>
=item B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate>
-the issuer certificate of a locally looked up certificate could not be found. This normally means
-the list of trusted certificates is not complete.
+the issuer certificate could not be found: this occurs if the issuer
+certificate of an untrusted certificate cannot be found.
=item B<21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate>
the root CA is marked to reject the specified purpose.
+=item B<29 X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch>
+
+the current candidate issuer certificate was rejected because its subject name
+did not match the issuer name of the current certificate. Only displayed when
+the B<-issuer_checks> option is set.
+
+=item B<30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch>
+
+the current candidate issuer certificate was rejected because its subject key
+identifier was present and did not match the authority key identifier current
+certificate. Only displayed when the B<-issuer_checks> option is set.
+
+=item B<31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch>
+
+the current candidate issuer certificate was rejected because its issuer name
+and serial number was present and did not match the authority key identifier
+of the current certificate. Only displayed when the B<-issuer_checks> option is set.
+
+=item B<32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing>
+
+the current candidate issuer certificate was rejected because its keyUsage extension
+does not permit certificate signing.
+
=item B<50 X509_V_ERR_APPLICATION_VERIFICATION: application verification failure>
an application specific error. Unused.
=back
+=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) or a directory (as specified by B<-CApath>. If they occur in both 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<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY> error codes.
+
=head1 SEE ALSO
L<x509(1)|x509(1)>
projects / oweals / openssl.git / blobdiff