verify.pod revision 296341
1=pod 2 3=head1 NAME 4 5verify - Utility to verify certificates. 6 7=head1 SYNOPSIS 8 9B<openssl> B<verify> 10[B<-CApath directory>] 11[B<-CAfile file>] 12[B<-purpose purpose>] 13[B<-policy arg>] 14[B<-ignore_critical>] 15[B<-crl_check>] 16[B<-crl_check_all>] 17[B<-policy_check>] 18[B<-explicit_policy>] 19[B<-inhibit_any>] 20[B<-inhibit_map>] 21[B<-x509_strict>] 22[B<-extended_crl>] 23[B<-use_deltas>] 24[B<-policy_print>] 25[B<-no_alt_chains>] 26[B<-untrusted file>] 27[B<-help>] 28[B<-issuer_checks>] 29[B<-attime timestamp>] 30[B<-verbose>] 31[B<->] 32[certificates] 33 34 35=head1 DESCRIPTION 36 37The B<verify> command verifies certificate chains. 38 39=head1 COMMAND OPTIONS 40 41=over 4 42 43=item B<-CApath directory> 44 45A directory of trusted certificates. The certificates should have names 46of the form: hash.0 or have symbolic links to them of this 47form ("hash" is the hashed certificate subject name: see the B<-hash> option 48of the B<x509> utility). Under Unix the B<c_rehash> script will automatically 49create symbolic links to a directory of certificates. 50 51=item B<-CAfile file> 52A file of trusted certificates. The file should contain multiple certificates 53in PEM format concatenated together. 54 55=item B<-untrusted file> 56 57A file of untrusted certificates. The file should contain multiple certificates 58in PEM format concatenated together. 59 60=item B<-purpose purpose> 61 62The intended use for the certificate. If this option is not specified, 63B<verify> will not consider certificate purpose during chain verification. 64Currently accepted uses are B<sslclient>, B<sslserver>, B<nssslserver>, 65B<smimesign>, B<smimeencrypt>. See the B<VERIFY OPERATION> section for more 66information. 67 68=item B<-help> 69 70Print out a usage message. 71 72=item B<-verbose> 73 74Print extra information about the operations being performed. 75 76=item B<-issuer_checks> 77 78Print out diagnostics relating to searches for the issuer certificate of the 79current certificate. This shows why each candidate issuer certificate was 80rejected. The presence of rejection messages does not itself imply that 81anything is wrong; during the normal verification process, several 82rejections may take place. 83 84=item B<-attime timestamp> 85 86Perform validation checks using time specified by B<timestamp> and not 87current system time. B<timestamp> is the number of seconds since 8801.01.1970 (UNIX time). 89 90=item B<-policy arg> 91 92Enable policy processing and add B<arg> to the user-initial-policy-set (see 93RFC5280). The policy B<arg> can be an object name an OID in numeric form. 94This argument can appear more than once. 95 96=item B<-policy_check> 97 98Enables certificate policy processing. 99 100=item B<-explicit_policy> 101 102Set policy variable require-explicit-policy (see RFC5280). 103 104=item B<-inhibit_any> 105 106Set policy variable inhibit-any-policy (see RFC5280). 107 108=item B<-inhibit_map> 109 110Set policy variable inhibit-policy-mapping (see RFC5280). 111 112=item B<-no_alt_chains> 113 114When building a certificate chain, if the first certificate chain found is not 115trusted, then OpenSSL will continue to check to see if an alternative chain can 116be found that is trusted. With this option that behaviour is suppressed so that 117only the first chain found is ever used. Using this option will force the 118behaviour to match that of previous OpenSSL versions. 119 120=item B<-policy_print> 121 122Print out diagnostics related to policy processing. 123 124=item B<-crl_check> 125 126Checks end entity certificate validity by attempting to look up a valid CRL. 127If a valid CRL cannot be found an error occurs. 128 129=item B<-crl_check_all> 130 131Checks the validity of B<all> certificates in the chain by attempting 132to look up valid CRLs. 133 134=item B<-ignore_critical> 135 136Normally if an unhandled critical extension is present which is not 137supported by OpenSSL the certificate is rejected (as required by RFC5280). 138If this option is set critical extensions are ignored. 139 140=item B<-x509_strict> 141 142For strict X.509 compliance, disable non-compliant workarounds for broken 143certificates. 144 145=item B<-extended_crl> 146 147Enable extended CRL features such as indirect CRLs and alternate CRL 148signing keys. 149 150=item B<-use_deltas> 151 152Enable support for delta CRLs. 153 154=item B<-check_ss_sig> 155 156Verify the signature on the self-signed root CA. This is disabled by default 157because it doesn't add any security. 158 159=item B<-> 160 161Indicates the last option. All arguments following this are assumed to be 162certificate files. This is useful if the first certificate filename begins 163with a B<->. 164 165=item B<certificates> 166 167One or more certificates to verify. If no certificates are given, B<verify> 168will attempt to read a certificate from standard input. Certificates must be 169in PEM format. 170 171=back 172 173=head1 VERIFY OPERATION 174 175The B<verify> program uses the same functions as the internal SSL and S/MIME 176verification, therefore this description applies to these verify operations 177too. 178 179There is one crucial difference between the verify operations performed 180by the B<verify> program: wherever possible an attempt is made to continue 181after an error whereas normally the verify operation would halt on the 182first error. This allows all the problems with a certificate chain to be 183determined. 184 185The verify operation consists of a number of separate steps. 186 187Firstly a certificate chain is built up starting from the supplied certificate 188and ending in the root CA. It is an error if the whole chain cannot be built 189up. The chain is built up by looking up the issuers certificate of the current 190certificate. If a certificate is found which is its own issuer it is assumed 191to be the root CA. 192 193The process of 'looking up the issuers certificate' itself involves a number 194of steps. In versions of OpenSSL before 0.9.5a the first certificate whose 195subject name matched the issuer of the current certificate was assumed to be 196the issuers certificate. In OpenSSL 0.9.6 and later all certificates 197whose subject name matches the issuer name of the current certificate are 198subject to further tests. The relevant authority key identifier components 199of the current certificate (if present) must match the subject key identifier 200(if present) and issuer and serial number of the candidate issuer, in addition 201the keyUsage extension of the candidate issuer (if present) must permit 202certificate signing. 203 204The lookup first looks in the list of untrusted certificates and if no match 205is found the remaining lookups are from the trusted certificates. The root CA 206is always looked up in the trusted certificate list: if the certificate to 207verify is a root certificate then an exact match must be found in the trusted 208list. 209 210The second operation is to check every untrusted certificate's extensions for 211consistency with the supplied purpose. If the B<-purpose> option is not included 212then no checks are done. The supplied or "leaf" certificate must have extensions 213compatible with the supplied purpose and all other certificates must also be valid 214CA certificates. The precise extensions required are described in more detail in 215the B<CERTIFICATE EXTENSIONS> section of the B<x509> utility. 216 217The third operation is to check the trust settings on the root CA. The root 218CA should be trusted for the supplied purpose. For compatibility with previous 219versions of SSLeay and OpenSSL a certificate with no trust settings is considered 220to be valid for all purposes. 221 222The final operation is to check the validity of the certificate chain. The validity 223period is checked against the current system time and the notBefore and notAfter 224dates in the certificate. The certificate signatures are also checked at this 225point. 226 227If all operations complete successfully then certificate is considered valid. If 228any operation fails then the certificate is not valid. 229 230=head1 DIAGNOSTICS 231 232When a verify operation fails the output messages can be somewhat cryptic. The 233general form of the error message is: 234 235 server.pem: /C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test CA (1024 bit) 236 error 24 at 1 depth lookup:invalid CA certificate 237 238The first line contains the name of the certificate being verified followed by 239the subject name of the certificate. The second line contains the error number 240and the depth. The depth is number of the certificate being verified when a 241problem was detected starting with zero for the certificate being verified itself 242then 1 for the CA that signed the certificate and so on. Finally a text version 243of the error number is presented. 244 245An exhaustive list of the error codes and messages is shown below, this also 246includes the name of the error code as defined in the header file x509_vfy.h 247Some of the error codes are defined but never returned: these are described 248as "unused". 249 250=over 4 251 252=item B<0 X509_V_OK: ok> 253 254the operation was successful. 255 256=item B<2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate> 257 258the issuer certificate of a looked up certificate could not be found. This 259normally means the list of trusted certificates is not complete. 260 261=item B<3 X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL> 262 263the CRL of a certificate could not be found. 264 265=item B<4 X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to decrypt certificate's signature> 266 267the certificate signature could not be decrypted. This means that the actual signature value 268could not be determined rather than it not matching the expected value, this is only 269meaningful for RSA keys. 270 271=item B<5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's signature> 272 273the CRL signature could not be decrypted: this means that the actual signature value 274could not be determined rather than it not matching the expected value. Unused. 275 276=item B<6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer public key> 277 278the public key in the certificate SubjectPublicKeyInfo could not be read. 279 280=item B<7 X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature failure> 281 282the signature of the certificate is invalid. 283 284=item B<8 X509_V_ERR_CRL_SIGNATURE_FAILURE: CRL signature failure> 285 286the signature of the certificate is invalid. 287 288=item B<9 X509_V_ERR_CERT_NOT_YET_VALID: certificate is not yet valid> 289 290the certificate is not yet valid: the notBefore date is after the current time. 291 292=item B<10 X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired> 293 294the certificate has expired: that is the notAfter date is before the current time. 295 296=item B<11 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid> 297 298the CRL is not yet valid. 299 300=item B<12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired> 301 302the CRL has expired. 303 304=item B<13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's notBefore field> 305 306the certificate notBefore field contains an invalid time. 307 308=item B<14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's notAfter field> 309 310the certificate notAfter field contains an invalid time. 311 312=item B<15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's lastUpdate field> 313 314the CRL lastUpdate field contains an invalid time. 315 316=item B<16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's nextUpdate field> 317 318the CRL nextUpdate field contains an invalid time. 319 320=item B<17 X509_V_ERR_OUT_OF_MEM: out of memory> 321 322an error occurred trying to allocate memory. This should never happen. 323 324=item B<18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate> 325 326the passed certificate is self signed and the same certificate cannot be found in the list of 327trusted certificates. 328 329=item B<19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain> 330 331the certificate chain could be built up using the untrusted certificates but the root could not 332be found locally. 333 334=item B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate> 335 336the issuer certificate could not be found: this occurs if the issuer 337certificate of an untrusted certificate cannot be found. 338 339=item B<21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate> 340 341no signatures could be verified because the chain contains only one certificate and it is not 342self signed. 343 344=item B<22 X509_V_ERR_CERT_CHAIN_TOO_LONG: certificate chain too long> 345 346the certificate chain length is greater than the supplied maximum depth. Unused. 347 348=item B<23 X509_V_ERR_CERT_REVOKED: certificate revoked> 349 350the certificate has been revoked. 351 352=item B<24 X509_V_ERR_INVALID_CA: invalid CA certificate> 353 354a CA certificate is invalid. Either it is not a CA or its extensions are not consistent 355with the supplied purpose. 356 357=item B<25 X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint exceeded> 358 359the basicConstraints pathlength parameter has been exceeded. 360 361=item B<26 X509_V_ERR_INVALID_PURPOSE: unsupported certificate purpose> 362 363the supplied certificate cannot be used for the specified purpose. 364 365=item B<27 X509_V_ERR_CERT_UNTRUSTED: certificate not trusted> 366 367the root CA is not marked as trusted for the specified purpose. 368 369=item B<28 X509_V_ERR_CERT_REJECTED: certificate rejected> 370 371the root CA is marked to reject the specified purpose. 372 373=item B<29 X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch> 374 375the current candidate issuer certificate was rejected because its subject name 376did not match the issuer name of the current certificate. Only displayed when 377the B<-issuer_checks> option is set. 378 379=item B<30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch> 380 381the current candidate issuer certificate was rejected because its subject key 382identifier was present and did not match the authority key identifier current 383certificate. Only displayed when the B<-issuer_checks> option is set. 384 385=item B<31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch> 386 387the current candidate issuer certificate was rejected because its issuer name 388and serial number was present and did not match the authority key identifier 389of the current certificate. Only displayed when the B<-issuer_checks> option is set. 390 391=item B<32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing> 392 393the current candidate issuer certificate was rejected because its keyUsage extension 394does not permit certificate signing. 395 396=item B<50 X509_V_ERR_APPLICATION_VERIFICATION: application verification failure> 397 398an application specific error. Unused. 399 400=back 401 402=head1 BUGS 403 404Although the issuer checks are a considerable improvement over the old technique they still 405suffer from limitations in the underlying X509_LOOKUP API. One consequence of this is that 406trusted certificates with matching subject name must either appear in a file (as specified by the 407B<-CAfile> option) or a directory (as specified by B<-CApath>. If they occur in both then only 408the certificates in the file will be recognised. 409 410Previous versions of OpenSSL assume certificates with matching subject name are identical and 411mishandled them. 412 413Previous versions of this documentation swapped the meaning of the 414B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT> and 415B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY> error codes. 416 417=head1 SEE ALSO 418 419L<x509(1)|x509(1)> 420 421=head1 HISTORY 422 423The -no_alt_chains options was first added to OpenSSL 1.0.1n and 1.0.2b. 424 425=cut 426