verify.pod revision 306196
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<-allow_proxy_certs>] 27[B<-untrusted file>] 28[B<-help>] 29[B<-issuer_checks>] 30[B<-attime timestamp>] 31[B<-verbose>] 32[B<->] 33[certificates] 34 35 36=head1 DESCRIPTION 37 38The B<verify> command verifies certificate chains. 39 40=head1 COMMAND OPTIONS 41 42=over 4 43 44=item B<-CApath directory> 45 46A directory of trusted certificates. The certificates should have names 47of the form: hash.0 or have symbolic links to them of this 48form ("hash" is the hashed certificate subject name: see the B<-hash> option 49of the B<x509> utility). Under Unix the B<c_rehash> script will automatically 50create symbolic links to a directory of certificates. 51 52=item B<-CAfile file> 53A file of trusted certificates. The file should contain multiple certificates 54in PEM format concatenated together. 55 56=item B<-untrusted file> 57 58A file of untrusted certificates. The file should contain multiple certificates 59in PEM format concatenated together. 60 61=item B<-purpose purpose> 62 63The intended use for the certificate. If this option is not specified, 64B<verify> will not consider certificate purpose during chain verification. 65Currently accepted uses are B<sslclient>, B<sslserver>, B<nssslserver>, 66B<smimesign>, B<smimeencrypt>. See the B<VERIFY OPERATION> section for more 67information. 68 69=item B<-help> 70 71Print out a usage message. 72 73=item B<-verbose> 74 75Print extra information about the operations being performed. 76 77=item B<-issuer_checks> 78 79Print out diagnostics relating to searches for the issuer certificate of the 80current certificate. This shows why each candidate issuer certificate was 81rejected. The presence of rejection messages does not itself imply that 82anything is wrong; during the normal verification process, several 83rejections may take place. 84 85=item B<-attime timestamp> 86 87Perform validation checks using time specified by B<timestamp> and not 88current system time. B<timestamp> is the number of seconds since 8901.01.1970 (UNIX time). 90 91=item B<-policy arg> 92 93Enable policy processing and add B<arg> to the user-initial-policy-set (see 94RFC5280). The policy B<arg> can be an object name an OID in numeric form. 95This argument can appear more than once. 96 97=item B<-policy_check> 98 99Enables certificate policy processing. 100 101=item B<-explicit_policy> 102 103Set policy variable require-explicit-policy (see RFC5280). 104 105=item B<-inhibit_any> 106 107Set policy variable inhibit-any-policy (see RFC5280). 108 109=item B<-inhibit_map> 110 111Set policy variable inhibit-policy-mapping (see RFC5280). 112 113=item B<-no_alt_chains> 114 115When building a certificate chain, if the first certificate chain found is not 116trusted, then OpenSSL will continue to check to see if an alternative chain can 117be found that is trusted. With this option that behaviour is suppressed so that 118only the first chain found is ever used. Using this option will force the 119behaviour to match that of previous OpenSSL versions. 120 121=item B<-allow_proxy_certs> 122 123Allow the verification of proxy certificates. 124 125=item B<-policy_print> 126 127Print out diagnostics related to policy processing. 128 129=item B<-crl_check> 130 131Checks end entity certificate validity by attempting to look up a valid CRL. 132If a valid CRL cannot be found an error occurs. 133 134=item B<-crl_check_all> 135 136Checks the validity of B<all> certificates in the chain by attempting 137to look up valid CRLs. 138 139=item B<-ignore_critical> 140 141Normally if an unhandled critical extension is present which is not 142supported by OpenSSL the certificate is rejected (as required by RFC5280). 143If this option is set critical extensions are ignored. 144 145=item B<-x509_strict> 146 147For strict X.509 compliance, disable non-compliant workarounds for broken 148certificates. 149 150=item B<-extended_crl> 151 152Enable extended CRL features such as indirect CRLs and alternate CRL 153signing keys. 154 155=item B<-use_deltas> 156 157Enable support for delta CRLs. 158 159=item B<-check_ss_sig> 160 161Verify the signature on the self-signed root CA. This is disabled by default 162because it doesn't add any security. 163 164=item B<-> 165 166Indicates the last option. All arguments following this are assumed to be 167certificate files. This is useful if the first certificate filename begins 168with a B<->. 169 170=item B<certificates> 171 172One or more certificates to verify. If no certificates are given, B<verify> 173will attempt to read a certificate from standard input. Certificates must be 174in PEM format. 175 176=back 177 178=head1 VERIFY OPERATION 179 180The B<verify> program uses the same functions as the internal SSL and S/MIME 181verification, therefore this description applies to these verify operations 182too. 183 184There is one crucial difference between the verify operations performed 185by the B<verify> program: wherever possible an attempt is made to continue 186after an error whereas normally the verify operation would halt on the 187first error. This allows all the problems with a certificate chain to be 188determined. 189 190The verify operation consists of a number of separate steps. 191 192Firstly a certificate chain is built up starting from the supplied certificate 193and ending in the root CA. It is an error if the whole chain cannot be built 194up. The chain is built up by looking up the issuers certificate of the current 195certificate. If a certificate is found which is its own issuer it is assumed 196to be the root CA. 197 198The process of 'looking up the issuers certificate' itself involves a number 199of steps. In versions of OpenSSL before 0.9.5a the first certificate whose 200subject name matched the issuer of the current certificate was assumed to be 201the issuers certificate. In OpenSSL 0.9.6 and later all certificates 202whose subject name matches the issuer name of the current certificate are 203subject to further tests. The relevant authority key identifier components 204of the current certificate (if present) must match the subject key identifier 205(if present) and issuer and serial number of the candidate issuer, in addition 206the keyUsage extension of the candidate issuer (if present) must permit 207certificate signing. 208 209The lookup first looks in the list of untrusted certificates and if no match 210is found the remaining lookups are from the trusted certificates. The root CA 211is always looked up in the trusted certificate list: if the certificate to 212verify is a root certificate then an exact match must be found in the trusted 213list. 214 215The second operation is to check every untrusted certificate's extensions for 216consistency with the supplied purpose. If the B<-purpose> option is not included 217then no checks are done. The supplied or "leaf" certificate must have extensions 218compatible with the supplied purpose and all other certificates must also be valid 219CA certificates. The precise extensions required are described in more detail in 220the B<CERTIFICATE EXTENSIONS> section of the B<x509> utility. 221 222The third operation is to check the trust settings on the root CA. The root 223CA should be trusted for the supplied purpose. For compatibility with previous 224versions of SSLeay and OpenSSL a certificate with no trust settings is considered 225to be valid for all purposes. 226 227The final operation is to check the validity of the certificate chain. The validity 228period is checked against the current system time and the notBefore and notAfter 229dates in the certificate. The certificate signatures are also checked at this 230point. 231 232If all operations complete successfully then certificate is considered valid. If 233any operation fails then the certificate is not valid. 234 235=head1 DIAGNOSTICS 236 237When a verify operation fails the output messages can be somewhat cryptic. The 238general form of the error message is: 239 240 server.pem: /C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test CA (1024 bit) 241 error 24 at 1 depth lookup:invalid CA certificate 242 243The first line contains the name of the certificate being verified followed by 244the subject name of the certificate. The second line contains the error number 245and the depth. The depth is number of the certificate being verified when a 246problem was detected starting with zero for the certificate being verified itself 247then 1 for the CA that signed the certificate and so on. Finally a text version 248of the error number is presented. 249 250An exhaustive list of the error codes and messages is shown below, this also 251includes the name of the error code as defined in the header file x509_vfy.h 252Some of the error codes are defined but never returned: these are described 253as "unused". 254 255=over 4 256 257=item B<0 X509_V_OK: ok> 258 259the operation was successful. 260 261=item B<2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate> 262 263the issuer certificate of a looked up certificate could not be found. This 264normally means the list of trusted certificates is not complete. 265 266=item B<3 X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL> 267 268the CRL of a certificate could not be found. 269 270=item B<4 X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to decrypt certificate's signature> 271 272the certificate signature could not be decrypted. This means that the actual signature value 273could not be determined rather than it not matching the expected value, this is only 274meaningful for RSA keys. 275 276=item B<5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's signature> 277 278the CRL signature could not be decrypted: this means that the actual signature value 279could not be determined rather than it not matching the expected value. Unused. 280 281=item B<6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer public key> 282 283the public key in the certificate SubjectPublicKeyInfo could not be read. 284 285=item B<7 X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature failure> 286 287the signature of the certificate is invalid. 288 289=item B<8 X509_V_ERR_CRL_SIGNATURE_FAILURE: CRL signature failure> 290 291the signature of the certificate is invalid. 292 293=item B<9 X509_V_ERR_CERT_NOT_YET_VALID: certificate is not yet valid> 294 295the certificate is not yet valid: the notBefore date is after the current time. 296 297=item B<10 X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired> 298 299the certificate has expired: that is the notAfter date is before the current time. 300 301=item B<11 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid> 302 303the CRL is not yet valid. 304 305=item B<12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired> 306 307the CRL has expired. 308 309=item B<13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's notBefore field> 310 311the certificate notBefore field contains an invalid time. 312 313=item B<14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's notAfter field> 314 315the certificate notAfter field contains an invalid time. 316 317=item B<15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's lastUpdate field> 318 319the CRL lastUpdate field contains an invalid time. 320 321=item B<16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's nextUpdate field> 322 323the CRL nextUpdate field contains an invalid time. 324 325=item B<17 X509_V_ERR_OUT_OF_MEM: out of memory> 326 327an error occurred trying to allocate memory. This should never happen. 328 329=item B<18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate> 330 331the passed certificate is self signed and the same certificate cannot be found in the list of 332trusted certificates. 333 334=item B<19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain> 335 336the certificate chain could be built up using the untrusted certificates but the root could not 337be found locally. 338 339=item B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate> 340 341the issuer certificate could not be found: this occurs if the issuer 342certificate of an untrusted certificate cannot be found. 343 344=item B<21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate> 345 346no signatures could be verified because the chain contains only one certificate and it is not 347self signed. 348 349=item B<22 X509_V_ERR_CERT_CHAIN_TOO_LONG: certificate chain too long> 350 351the certificate chain length is greater than the supplied maximum depth. Unused. 352 353=item B<23 X509_V_ERR_CERT_REVOKED: certificate revoked> 354 355the certificate has been revoked. 356 357=item B<24 X509_V_ERR_INVALID_CA: invalid CA certificate> 358 359a CA certificate is invalid. Either it is not a CA or its extensions are not consistent 360with the supplied purpose. 361 362=item B<25 X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint exceeded> 363 364the basicConstraints pathlength parameter has been exceeded. 365 366=item B<26 X509_V_ERR_INVALID_PURPOSE: unsupported certificate purpose> 367 368the supplied certificate cannot be used for the specified purpose. 369 370=item B<27 X509_V_ERR_CERT_UNTRUSTED: certificate not trusted> 371 372the root CA is not marked as trusted for the specified purpose. 373 374=item B<28 X509_V_ERR_CERT_REJECTED: certificate rejected> 375 376the root CA is marked to reject the specified purpose. 377 378=item B<29 X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch> 379 380the current candidate issuer certificate was rejected because its subject name 381did not match the issuer name of the current certificate. Only displayed when 382the B<-issuer_checks> option is set. 383 384=item B<30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch> 385 386the current candidate issuer certificate was rejected because its subject key 387identifier was present and did not match the authority key identifier current 388certificate. Only displayed when the B<-issuer_checks> option is set. 389 390=item B<31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch> 391 392the current candidate issuer certificate was rejected because its issuer name 393and serial number was present and did not match the authority key identifier 394of the current certificate. Only displayed when the B<-issuer_checks> option is set. 395 396=item B<32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing> 397 398the current candidate issuer certificate was rejected because its keyUsage extension 399does not permit certificate signing. 400 401=item B<50 X509_V_ERR_APPLICATION_VERIFICATION: application verification failure> 402 403an application specific error. Unused. 404 405=back 406 407=head1 BUGS 408 409Although the issuer checks are a considerable improvement over the old technique they still 410suffer from limitations in the underlying X509_LOOKUP API. One consequence of this is that 411trusted certificates with matching subject name must either appear in a file (as specified by the 412B<-CAfile> option) or a directory (as specified by B<-CApath>. If they occur in both then only 413the certificates in the file will be recognised. 414 415Previous versions of OpenSSL assume certificates with matching subject name are identical and 416mishandled them. 417 418Previous versions of this documentation swapped the meaning of the 419B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT> and 420B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY> error codes. 421 422=head1 SEE ALSO 423 424L<x509(1)|x509(1)> 425 426=head1 HISTORY 427 428The -no_alt_chains options was first added to OpenSSL 1.0.1n and 1.0.2b. 429 430=cut 431