verify.pod revision 269686
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<-untrusted file>] 26[B<-help>] 27[B<-issuer_checks>] 28[B<-attime timestamp>] 29[B<-verbose>] 30[B<->] 31[certificates] 32 33 34=head1 DESCRIPTION 35 36The B<verify> command verifies certificate chains. 37 38=head1 COMMAND OPTIONS 39 40=over 4 41 42=item B<-CApath directory> 43 44A directory of trusted certificates. The certificates should have names 45of the form: hash.0 or have symbolic links to them of this 46form ("hash" is the hashed certificate subject name: see the B<-hash> option 47of the B<x509> utility). Under Unix the B<c_rehash> script will automatically 48create symbolic links to a directory of certificates. 49 50=item B<-CAfile file> 51A file of trusted certificates. The file should contain multiple certificates 52in PEM format concatenated together. 53 54=item B<-untrusted file> 55 56A file of untrusted certificates. The file should contain multiple certificates 57in PEM format concatenated together. 58 59=item B<-purpose purpose> 60 61The intended use for the certificate. If this option is not specified, 62B<verify> will not consider certificate purpose during chain verification. 63Currently accepted uses are B<sslclient>, B<sslserver>, B<nssslserver>, 64B<smimesign>, B<smimeencrypt>. See the B<VERIFY OPERATION> section for more 65information. 66 67=item B<-help> 68 69Print out a usage message. 70 71=item B<-verbose> 72 73Print extra information about the operations being performed. 74 75=item B<-issuer_checks> 76 77Print out diagnostics relating to searches for the issuer certificate of the 78current certificate. This shows why each candidate issuer certificate was 79rejected. The presence of rejection messages does not itself imply that 80anything is wrong; during the normal verification process, several 81rejections may take place. 82 83=item B<-attime timestamp> 84 85Perform validation checks using time specified by B<timestamp> and not 86current system time. B<timestamp> is the number of seconds since 8701.01.1970 (UNIX time). 88 89=item B<-policy arg> 90 91Enable policy processing and add B<arg> to the user-initial-policy-set (see 92RFC5280). The policy B<arg> can be an object name an OID in numeric form. 93This argument can appear more than once. 94 95=item B<-policy_check> 96 97Enables certificate policy processing. 98 99=item B<-explicit_policy> 100 101Set policy variable require-explicit-policy (see RFC5280). 102 103=item B<-inhibit_any> 104 105Set policy variable inhibit-any-policy (see RFC5280). 106 107=item B<-inhibit_map> 108 109Set policy variable inhibit-policy-mapping (see RFC5280). 110 111=item B<-policy_print> 112 113Print out diagnostics related to policy processing. 114 115=item B<-crl_check> 116 117Checks end entity certificate validity by attempting to look up a valid CRL. 118If a valid CRL cannot be found an error occurs. 119 120=item B<-crl_check_all> 121 122Checks the validity of B<all> certificates in the chain by attempting 123to look up valid CRLs. 124 125=item B<-ignore_critical> 126 127Normally if an unhandled critical extension is present which is not 128supported by OpenSSL the certificate is rejected (as required by RFC5280). 129If this option is set critical extensions are ignored. 130 131=item B<-x509_strict> 132 133For strict X.509 compliance, disable non-compliant workarounds for broken 134certificates. 135 136=item B<-extended_crl> 137 138Enable extended CRL features such as indirect CRLs and alternate CRL 139signing keys. 140 141=item B<-use_deltas> 142 143Enable support for delta CRLs. 144 145=item B<-check_ss_sig> 146 147Verify the signature on the self-signed root CA. This is disabled by default 148because it doesn't add any security. 149 150=item B<-> 151 152Indicates the last option. All arguments following this are assumed to be 153certificate files. This is useful if the first certificate filename begins 154with a B<->. 155 156=item B<certificates> 157 158One or more certificates to verify. If no certificates are given, B<verify> 159will attempt to read a certificate from standard input. Certificates must be 160in PEM format. 161 162=back 163 164=head1 VERIFY OPERATION 165 166The B<verify> program uses the same functions as the internal SSL and S/MIME 167verification, therefore this description applies to these verify operations 168too. 169 170There is one crucial difference between the verify operations performed 171by the B<verify> program: wherever possible an attempt is made to continue 172after an error whereas normally the verify operation would halt on the 173first error. This allows all the problems with a certificate chain to be 174determined. 175 176The verify operation consists of a number of separate steps. 177 178Firstly a certificate chain is built up starting from the supplied certificate 179and ending in the root CA. It is an error if the whole chain cannot be built 180up. The chain is built up by looking up the issuers certificate of the current 181certificate. If a certificate is found which is its own issuer it is assumed 182to be the root CA. 183 184The process of 'looking up the issuers certificate' itself involves a number 185of steps. In versions of OpenSSL before 0.9.5a the first certificate whose 186subject name matched the issuer of the current certificate was assumed to be 187the issuers certificate. In OpenSSL 0.9.6 and later all certificates 188whose subject name matches the issuer name of the current certificate are 189subject to further tests. The relevant authority key identifier components 190of the current certificate (if present) must match the subject key identifier 191(if present) and issuer and serial number of the candidate issuer, in addition 192the keyUsage extension of the candidate issuer (if present) must permit 193certificate signing. 194 195The lookup first looks in the list of untrusted certificates and if no match 196is found the remaining lookups are from the trusted certificates. The root CA 197is always looked up in the trusted certificate list: if the certificate to 198verify is a root certificate then an exact match must be found in the trusted 199list. 200 201The second operation is to check every untrusted certificate's extensions for 202consistency with the supplied purpose. If the B<-purpose> option is not included 203then no checks are done. The supplied or "leaf" certificate must have extensions 204compatible with the supplied purpose and all other certificates must also be valid 205CA certificates. The precise extensions required are described in more detail in 206the B<CERTIFICATE EXTENSIONS> section of the B<x509> utility. 207 208The third operation is to check the trust settings on the root CA. The root 209CA should be trusted for the supplied purpose. For compatibility with previous 210versions of SSLeay and OpenSSL a certificate with no trust settings is considered 211to be valid for all purposes. 212 213The final operation is to check the validity of the certificate chain. The validity 214period is checked against the current system time and the notBefore and notAfter 215dates in the certificate. The certificate signatures are also checked at this 216point. 217 218If all operations complete successfully then certificate is considered valid. If 219any operation fails then the certificate is not valid. 220 221=head1 DIAGNOSTICS 222 223When a verify operation fails the output messages can be somewhat cryptic. The 224general form of the error message is: 225 226 server.pem: /C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test CA (1024 bit) 227 error 24 at 1 depth lookup:invalid CA certificate 228 229The first line contains the name of the certificate being verified followed by 230the subject name of the certificate. The second line contains the error number 231and the depth. The depth is number of the certificate being verified when a 232problem was detected starting with zero for the certificate being verified itself 233then 1 for the CA that signed the certificate and so on. Finally a text version 234of the error number is presented. 235 236An exhaustive list of the error codes and messages is shown below, this also 237includes the name of the error code as defined in the header file x509_vfy.h 238Some of the error codes are defined but never returned: these are described 239as "unused". 240 241=over 4 242 243=item B<0 X509_V_OK: ok> 244 245the operation was successful. 246 247=item B<2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate> 248 249the issuer certificate of a looked up certificate could not be found. This 250normally means the list of trusted certificates is not complete. 251 252=item B<3 X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL> 253 254the CRL of a certificate could not be found. 255 256=item B<4 X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to decrypt certificate's signature> 257 258the certificate signature could not be decrypted. This means that the actual signature value 259could not be determined rather than it not matching the expected value, this is only 260meaningful for RSA keys. 261 262=item B<5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's signature> 263 264the CRL signature could not be decrypted: this means that the actual signature value 265could not be determined rather than it not matching the expected value. Unused. 266 267=item B<6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer public key> 268 269the public key in the certificate SubjectPublicKeyInfo could not be read. 270 271=item B<7 X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature failure> 272 273the signature of the certificate is invalid. 274 275=item B<8 X509_V_ERR_CRL_SIGNATURE_FAILURE: CRL signature failure> 276 277the signature of the certificate is invalid. 278 279=item B<9 X509_V_ERR_CERT_NOT_YET_VALID: certificate is not yet valid> 280 281the certificate is not yet valid: the notBefore date is after the current time. 282 283=item B<10 X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired> 284 285the certificate has expired: that is the notAfter date is before the current time. 286 287=item B<11 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid> 288 289the CRL is not yet valid. 290 291=item B<12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired> 292 293the CRL has expired. 294 295=item B<13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's notBefore field> 296 297the certificate notBefore field contains an invalid time. 298 299=item B<14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's notAfter field> 300 301the certificate notAfter field contains an invalid time. 302 303=item B<15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's lastUpdate field> 304 305the CRL lastUpdate field contains an invalid time. 306 307=item B<16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's nextUpdate field> 308 309the CRL nextUpdate field contains an invalid time. 310 311=item B<17 X509_V_ERR_OUT_OF_MEM: out of memory> 312 313an error occurred trying to allocate memory. This should never happen. 314 315=item B<18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate> 316 317the passed certificate is self signed and the same certificate cannot be found in the list of 318trusted certificates. 319 320=item B<19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain> 321 322the certificate chain could be built up using the untrusted certificates but the root could not 323be found locally. 324 325=item B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate> 326 327the issuer certificate could not be found: this occurs if the issuer 328certificate of an untrusted certificate cannot be found. 329 330=item B<21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate> 331 332no signatures could be verified because the chain contains only one certificate and it is not 333self signed. 334 335=item B<22 X509_V_ERR_CERT_CHAIN_TOO_LONG: certificate chain too long> 336 337the certificate chain length is greater than the supplied maximum depth. Unused. 338 339=item B<23 X509_V_ERR_CERT_REVOKED: certificate revoked> 340 341the certificate has been revoked. 342 343=item B<24 X509_V_ERR_INVALID_CA: invalid CA certificate> 344 345a CA certificate is invalid. Either it is not a CA or its extensions are not consistent 346with the supplied purpose. 347 348=item B<25 X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint exceeded> 349 350the basicConstraints pathlength parameter has been exceeded. 351 352=item B<26 X509_V_ERR_INVALID_PURPOSE: unsupported certificate purpose> 353 354the supplied certificate cannot be used for the specified purpose. 355 356=item B<27 X509_V_ERR_CERT_UNTRUSTED: certificate not trusted> 357 358the root CA is not marked as trusted for the specified purpose. 359 360=item B<28 X509_V_ERR_CERT_REJECTED: certificate rejected> 361 362the root CA is marked to reject the specified purpose. 363 364=item B<29 X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch> 365 366the current candidate issuer certificate was rejected because its subject name 367did not match the issuer name of the current certificate. Only displayed when 368the B<-issuer_checks> option is set. 369 370=item B<30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch> 371 372the current candidate issuer certificate was rejected because its subject key 373identifier was present and did not match the authority key identifier current 374certificate. Only displayed when the B<-issuer_checks> option is set. 375 376=item B<31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch> 377 378the current candidate issuer certificate was rejected because its issuer name 379and serial number was present and did not match the authority key identifier 380of the current certificate. Only displayed when the B<-issuer_checks> option is set. 381 382=item B<32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing> 383 384the current candidate issuer certificate was rejected because its keyUsage extension 385does not permit certificate signing. 386 387=item B<50 X509_V_ERR_APPLICATION_VERIFICATION: application verification failure> 388 389an application specific error. Unused. 390 391=back 392 393=head1 BUGS 394 395Although the issuer checks are a considerable improvement over the old technique they still 396suffer from limitations in the underlying X509_LOOKUP API. One consequence of this is that 397trusted certificates with matching subject name must either appear in a file (as specified by the 398B<-CAfile> option) or a directory (as specified by B<-CApath>. If they occur in both then only 399the certificates in the file will be recognised. 400 401Previous versions of OpenSSL assume certificates with matching subject name are identical and 402mishandled them. 403 404Previous versions of this documentation swapped the meaning of the 405B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT> and 406B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY> error codes. 407 408=head1 SEE ALSO 409 410L<x509(1)|x509(1)> 411 412=cut 413