5 verify - Utility to verify certificates.
10 [B<-CApath directory>]
23 The B<verify> command verifies certificate chains.
25 =head1 COMMAND OPTIONS
29 =item B<-CApath directory>
31 A directory of trusted certificates. The certificates should have names
32 of the form: hash.0 or have symbolic links to them of this
33 form ("hash" is the hashed certificate subject name: see the B<-hash> option
34 of the B<x509> utility). Under Unix the B<c_rehash> script will automatically
35 create symbolic links to a directory of certificates.
39 A file of trusted certificates. The file should contain multiple certificates
40 in PEM format concatenated together.
42 =item B<-untrusted file>
44 A file of untrusted certificates. The file should contain multiple certificates
46 =item B<-purpose purpose>
48 the intended use for the certificate. Without this option no chain verification
49 will be done. Currently accepted uses are B<sslclient>, B<sslserver>,
50 B<nssslserver>, B<smimesign>, B<smimeencrypt>. See the B<VERIFY OPERATION>
51 section for more information.
55 prints out a usage message.
59 print extra information about the operations being performed.
61 =item B<-issuer_checks>
63 print out diagnostics relating to searches for the issuer certificate
64 of the current certificate. This shows why each candidate issuer
65 certificate was rejected. However the presence of rejection messages
66 does not itself imply that anything is wrong: during the normal
67 verify process several rejections may take place.
69 =item B<-check_ss_sig>
71 Verify the signature on the self-signed root CA. This is disabled by default
72 because it doesn't add any security.
76 marks the last option. All arguments following this are assumed to be
77 certificate files. This is useful if the first certificate filename begins
82 one or more certificates to verify. If no certificate filenames are included
83 then an attempt is made to read a certificate from standard input. They should
89 =head1 VERIFY OPERATION
91 The B<verify> program uses the same functions as the internal SSL and S/MIME
92 verification, therefore this description applies to these verify operations
95 There is one crucial difference between the verify operations performed
96 by the B<verify> program: wherever possible an attempt is made to continue
97 after an error whereas normally the verify operation would halt on the
98 first error. This allows all the problems with a certificate chain to be
101 The verify operation consists of a number of separate steps.
103 Firstly a certificate chain is built up starting from the supplied certificate
104 and ending in the root CA. It is an error if the whole chain cannot be built
105 up. The chain is built up by looking up the issuers certificate of the current
106 certificate. If a certificate is found which is its own issuer it is assumed
109 The process of 'looking up the issuers certificate' itself involves a number
110 of steps. In versions of OpenSSL before 0.9.5a the first certificate whose
111 subject name matched the issuer of the current certificate was assumed to be
112 the issuers certificate. In OpenSSL 0.9.6 and later all certificates
113 whose subject name matches the issuer name of the current certificate are
114 subject to further tests. The relevant authority key identifier components
115 of the current certificate (if present) must match the subject key identifier
116 (if present) and issuer and serial number of the candidate issuer, in addition
117 the keyUsage extension of the candidate issuer (if present) must permit
120 The lookup first looks in the list of untrusted certificates and if no match
121 is found the remaining lookups are from the trusted certificates. The root CA
122 is always looked up in the trusted certificate list: if the certificate to
123 verify is a root certificate then an exact match must be found in the trusted
126 The second operation is to check every untrusted certificate's extensions for
127 consistency with the supplied purpose. If the B<-purpose> option is not included
128 then no checks are done. The supplied or "leaf" certificate must have extensions
129 compatible with the supplied purpose and all other certificates must also be valid
130 CA certificates. The precise extensions required are described in more detail in
131 the B<CERTIFICATE EXTENSIONS> section of the B<x509> utility.
133 The third operation is to check the trust settings on the root CA. The root
134 CA should be trusted for the supplied purpose. For compatibility with previous
135 versions of SSLeay and OpenSSL a certificate with no trust settings is considered
136 to be valid for all purposes.
138 The final operation is to check the validity of the certificate chain. The validity
139 period is checked against the current system time and the notBefore and notAfter
140 dates in the certificate. The certificate signatures are also checked at this
143 If all operations complete successfully then certificate is considered valid. If
144 any operation fails then the certificate is not valid.
148 When a verify operation fails the output messages can be somewhat cryptic. The
149 general form of the error message is:
151 server.pem: /C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test CA (1024 bit)
152 error 24 at 1 depth lookup:invalid CA certificate
154 The first line contains the name of the certificate being verified followed by
155 the subject name of the certificate. The second line contains the error number
156 and the depth. The depth is number of the certificate being verified when a
157 problem was detected starting with zero for the certificate being verified itself
158 then 1 for the CA that signed the certificate and so on. Finally a text version
159 of the error number is presented.
161 An exhaustive list of the error codes and messages is shown below, this also
162 includes the name of the error code as defined in the header file x509_vfy.h
163 Some of the error codes are defined but never returned: these are described
168 =item B<0 X509_V_OK: ok>
170 the operation was successful.
172 =item B<2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate>
174 the issuer certificate of a looked up certificate could not be found. This
175 normally means the list of trusted certificates is not complete.
177 =item B<3 X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL>
179 the CRL of a certificate could not be found. Unused.
181 =item B<4 X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to decrypt certificate's signature>
183 the certificate signature could not be decrypted. This means that the actual signature value
184 could not be determined rather than it not matching the expected value, this is only
185 meaningful for RSA keys.
187 =item B<5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's signature>
189 the CRL signature could not be decrypted: this means that the actual signature value
190 could not be determined rather than it not matching the expected value. Unused.
192 =item B<6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer public key>
194 the public key in the certificate SubjectPublicKeyInfo could not be read.
196 =item B<7 X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature failure>
198 the signature of the certificate is invalid.
200 =item B<8 X509_V_ERR_CRL_SIGNATURE_FAILURE: CRL signature failure>
202 the signature of the certificate is invalid. Unused.
204 =item B<9 X509_V_ERR_CERT_NOT_YET_VALID: certificate is not yet valid>
206 the certificate is not yet valid: the notBefore date is after the current time.
208 =item B<10 X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired>
210 the certificate has expired: that is the notAfter date is before the current time.
212 =item B<11 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid>
214 the CRL is not yet valid. Unused.
216 =item B<12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired>
218 the CRL has expired. Unused.
220 =item B<13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's notBefore field>
222 the certificate notBefore field contains an invalid time.
224 =item B<14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's notAfter field>
226 the certificate notAfter field contains an invalid time.
228 =item B<15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's lastUpdate field>
230 the CRL lastUpdate field contains an invalid time. Unused.
232 =item B<16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's nextUpdate field>
234 the CRL nextUpdate field contains an invalid time. Unused.
236 =item B<17 X509_V_ERR_OUT_OF_MEM: out of memory>
238 an error occurred trying to allocate memory. This should never happen.
240 =item B<18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate>
242 the passed certificate is self signed and the same certificate cannot be found in the list of
243 trusted certificates.
245 =item B<19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain>
247 the certificate chain could be built up using the untrusted certificates but the root could not
250 =item B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate>
252 the issuer certificate could not be found: this occurs if the issuer
253 certificate of an untrusted certificate cannot be found.
255 =item B<21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate>
257 no signatures could be verified because the chain contains only one certificate and it is not
260 =item B<22 X509_V_ERR_CERT_CHAIN_TOO_LONG: certificate chain too long>
262 the certificate chain length is greater than the supplied maximum depth. Unused.
264 =item B<23 X509_V_ERR_CERT_REVOKED: certificate revoked>
266 the certificate has been revoked. Unused.
268 =item B<24 X509_V_ERR_INVALID_CA: invalid CA certificate>
270 a CA certificate is invalid. Either it is not a CA or its extensions are not consistent
271 with the supplied purpose.
273 =item B<25 X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint exceeded>
275 the basicConstraints pathlength parameter has been exceeded.
277 =item B<26 X509_V_ERR_INVALID_PURPOSE: unsupported certificate purpose>
279 the supplied certificate cannot be used for the specified purpose.
281 =item B<27 X509_V_ERR_CERT_UNTRUSTED: certificate not trusted>
283 the root CA is not marked as trusted for the specified purpose.
285 =item B<28 X509_V_ERR_CERT_REJECTED: certificate rejected>
287 the root CA is marked to reject the specified purpose.
289 =item B<29 X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch>
291 the current candidate issuer certificate was rejected because its subject name
292 did not match the issuer name of the current certificate. Only displayed when
293 the B<-issuer_checks> option is set.
295 =item B<30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch>
297 the current candidate issuer certificate was rejected because its subject key
298 identifier was present and did not match the authority key identifier current
299 certificate. Only displayed when the B<-issuer_checks> option is set.
301 =item B<31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch>
303 the current candidate issuer certificate was rejected because its issuer name
304 and serial number was present and did not match the authority key identifier
305 of the current certificate. Only displayed when the B<-issuer_checks> option is set.
307 =item B<32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing>
309 the current candidate issuer certificate was rejected because its keyUsage extension
310 does not permit certificate signing.
312 =item B<50 X509_V_ERR_APPLICATION_VERIFICATION: application verification failure>
314 an application specific error. Unused.
320 Although the issuer checks are a considerable improvement over the old technique they still
321 suffer from limitations in the underlying X509_LOOKUP API. One consequence of this is that
322 trusted certificates with matching subject name must either appear in a file (as specified by the
323 B<-CAfile> option) or a directory (as specified by B<-CApath>. If they occur in both then only
324 the certificates in the file will be recognised.
326 Previous versions of OpenSSL assume certificates with matching subject name are identical and
329 Previous versions of this documentation swapped the meaning of the
330 B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT> and
331 B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY> error codes.