verify.pod 14 KB

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  1. =pod
  2. =head1 NAME
  3. verify - Utility to verify certificates.
  4. =head1 SYNOPSIS
  5. B<openssl> B<verify>
  6. [B<-CApath directory>]
  7. [B<-CAfile file>]
  8. [B<-purpose purpose>]
  9. [B<-policy arg>]
  10. [B<-ignore_critical>]
  11. [B<-crl_check>]
  12. [B<-crl_check_all>]
  13. [B<-policy_check>]
  14. [B<-explicit_policy>]
  15. [B<-inhibit_any>]
  16. [B<-inhibit_map>]
  17. [B<-x509_strict>]
  18. [B<-extended_crl>]
  19. [B<-use_deltas>]
  20. [B<-policy_print>]
  21. [B<-untrusted file>]
  22. [B<-help>]
  23. [B<-issuer_checks>]
  24. [B<-verbose>]
  25. [B<->]
  26. [certificates]
  27. =head1 DESCRIPTION
  28. The B<verify> command verifies certificate chains.
  29. =head1 COMMAND OPTIONS
  30. =over 4
  31. =item B<-CApath directory>
  32. A directory of trusted certificates. The certificates should have names
  33. of the form: hash.0 or have symbolic links to them of this
  34. form ("hash" is the hashed certificate subject name: see the B<-hash> option
  35. of the B<x509> utility). Under Unix the B<c_rehash> script will automatically
  36. create symbolic links to a directory of certificates.
  37. =item B<-CAfile file>
  38. A file of trusted certificates. The file should contain multiple certificates
  39. in PEM format concatenated together.
  40. =item B<-untrusted file>
  41. A file of untrusted certificates. The file should contain multiple certificates
  42. =item B<-purpose purpose>
  43. the intended use for the certificate. Without this option no chain verification
  44. will be done. Currently accepted uses are B<sslclient>, B<sslserver>,
  45. B<nssslserver>, B<smimesign>, B<smimeencrypt>. See the B<VERIFY OPERATION>
  46. section for more information.
  47. =item B<-help>
  48. prints out a usage message.
  49. =item B<-verbose>
  50. print extra information about the operations being performed.
  51. =item B<-issuer_checks>
  52. print out diagnostics relating to searches for the issuer certificate
  53. of the current certificate. This shows why each candidate issuer
  54. certificate was rejected. However the presence of rejection messages
  55. does not itself imply that anything is wrong: during the normal
  56. verify process several rejections may take place.
  57. =item B<-policy arg>
  58. Enable policy processing and add B<arg> to the user-initial-policy-set
  59. (see RFC3280 et al). The policy B<arg> can be an object name an OID in numeric
  60. form. This argument can appear more than once.
  61. =item B<-policy_check>
  62. Enables certificate policy processing.
  63. =item B<-explicit_policy>
  64. Set policy variable require-explicit-policy (see RFC3280 et al).
  65. =item B<-inhibit_any>
  66. Set policy variable inhibit-any-policy (see RFC3280 et al).
  67. =item B<-inhibit_map>
  68. Set policy variable inhibit-policy-mapping (see RFC3280 et al).
  69. =item B<-policy_print>
  70. Print out diagnostics, related to policy checking
  71. =item B<-crl_check>
  72. Checks end entity certificate validity by attempting to lookup a valid CRL.
  73. If a valid CRL cannot be found an error occurs.
  74. =item B<-crl_check_all>
  75. Checks the validity of B<all> certificates in the chain by attempting
  76. to lookup valid CRLs.
  77. =item B<-ignore_critical>
  78. Normally if an unhandled critical extension is present which is not
  79. supported by OpenSSL the certificate is rejected (as required by
  80. RFC3280 et al). If this option is set critical extensions are
  81. ignored.
  82. =item B<-x509_strict>
  83. Disable workarounds for broken certificates which have to be disabled
  84. for strict X.509 compliance.
  85. =item B<-extended_crl>
  86. Enable extended CRL features such as indirect CRLs and alternate CRL
  87. signing keys.
  88. =item B<-use_deltas>
  89. Enable support for delta CRLs.
  90. =item B<-check_ss_sig>
  91. Verify the signature on the self-signed root CA. This is disabled by default
  92. because it doesn't add any security.
  93. =item B<->
  94. marks the last option. All arguments following this are assumed to be
  95. certificate files. This is useful if the first certificate filename begins
  96. with a B<->.
  97. =item B<certificates>
  98. one or more certificates to verify. If no certificate filenames are included
  99. then an attempt is made to read a certificate from standard input. They should
  100. all be in PEM format.
  101. =back
  102. =head1 VERIFY OPERATION
  103. The B<verify> program uses the same functions as the internal SSL and S/MIME
  104. verification, therefore this description applies to these verify operations
  105. too.
  106. There is one crucial difference between the verify operations performed
  107. by the B<verify> program: wherever possible an attempt is made to continue
  108. after an error whereas normally the verify operation would halt on the
  109. first error. This allows all the problems with a certificate chain to be
  110. determined.
  111. The verify operation consists of a number of separate steps.
  112. Firstly a certificate chain is built up starting from the supplied certificate
  113. and ending in the root CA. It is an error if the whole chain cannot be built
  114. up. The chain is built up by looking up the issuers certificate of the current
  115. certificate. If a certificate is found which is its own issuer it is assumed
  116. to be the root CA.
  117. The process of 'looking up the issuers certificate' itself involves a number
  118. of steps. In versions of OpenSSL before 0.9.5a the first certificate whose
  119. subject name matched the issuer of the current certificate was assumed to be
  120. the issuers certificate. In OpenSSL 0.9.6 and later all certificates
  121. whose subject name matches the issuer name of the current certificate are
  122. subject to further tests. The relevant authority key identifier components
  123. of the current certificate (if present) must match the subject key identifier
  124. (if present) and issuer and serial number of the candidate issuer, in addition
  125. the keyUsage extension of the candidate issuer (if present) must permit
  126. certificate signing.
  127. The lookup first looks in the list of untrusted certificates and if no match
  128. is found the remaining lookups are from the trusted certificates. The root CA
  129. is always looked up in the trusted certificate list: if the certificate to
  130. verify is a root certificate then an exact match must be found in the trusted
  131. list.
  132. The second operation is to check every untrusted certificate's extensions for
  133. consistency with the supplied purpose. If the B<-purpose> option is not included
  134. then no checks are done. The supplied or "leaf" certificate must have extensions
  135. compatible with the supplied purpose and all other certificates must also be valid
  136. CA certificates. The precise extensions required are described in more detail in
  137. the B<CERTIFICATE EXTENSIONS> section of the B<x509> utility.
  138. The third operation is to check the trust settings on the root CA. The root
  139. CA should be trusted for the supplied purpose. For compatibility with previous
  140. versions of SSLeay and OpenSSL a certificate with no trust settings is considered
  141. to be valid for all purposes.
  142. The final operation is to check the validity of the certificate chain. The validity
  143. period is checked against the current system time and the notBefore and notAfter
  144. dates in the certificate. The certificate signatures are also checked at this
  145. point.
  146. If all operations complete successfully then certificate is considered valid. If
  147. any operation fails then the certificate is not valid.
  148. =head1 DIAGNOSTICS
  149. When a verify operation fails the output messages can be somewhat cryptic. The
  150. 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
  153. The first line contains the name of the certificate being verified followed by
  154. the subject name of the certificate. The second line contains the error number
  155. and the depth. The depth is number of the certificate being verified when a
  156. problem was detected starting with zero for the certificate being verified itself
  157. then 1 for the CA that signed the certificate and so on. Finally a text version
  158. of the error number is presented.
  159. An exhaustive list of the error codes and messages is shown below, this also
  160. includes the name of the error code as defined in the header file x509_vfy.h
  161. Some of the error codes are defined but never returned: these are described
  162. as "unused".
  163. =over 4
  164. =item B<0 X509_V_OK: ok>
  165. the operation was successful.
  166. =item B<2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate>
  167. the issuer certificate of a looked up certificate could not be found. This
  168. normally means the list of trusted certificates is not complete.
  169. =item B<3 X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL>
  170. the CRL of a certificate could not be found.
  171. =item B<4 X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to decrypt certificate's signature>
  172. the certificate signature could not be decrypted. This means that the actual signature value
  173. could not be determined rather than it not matching the expected value, this is only
  174. meaningful for RSA keys.
  175. =item B<5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's signature>
  176. the CRL signature could not be decrypted: this means that the actual signature value
  177. could not be determined rather than it not matching the expected value. Unused.
  178. =item B<6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer public key>
  179. the public key in the certificate SubjectPublicKeyInfo could not be read.
  180. =item B<7 X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature failure>
  181. the signature of the certificate is invalid.
  182. =item B<8 X509_V_ERR_CRL_SIGNATURE_FAILURE: CRL signature failure>
  183. the signature of the certificate is invalid.
  184. =item B<9 X509_V_ERR_CERT_NOT_YET_VALID: certificate is not yet valid>
  185. the certificate is not yet valid: the notBefore date is after the current time.
  186. =item B<10 X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired>
  187. the certificate has expired: that is the notAfter date is before the current time.
  188. =item B<11 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid>
  189. the CRL is not yet valid.
  190. =item B<12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired>
  191. the CRL has expired.
  192. =item B<13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's notBefore field>
  193. the certificate notBefore field contains an invalid time.
  194. =item B<14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's notAfter field>
  195. the certificate notAfter field contains an invalid time.
  196. =item B<15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's lastUpdate field>
  197. the CRL lastUpdate field contains an invalid time.
  198. =item B<16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's nextUpdate field>
  199. the CRL nextUpdate field contains an invalid time.
  200. =item B<17 X509_V_ERR_OUT_OF_MEM: out of memory>
  201. an error occurred trying to allocate memory. This should never happen.
  202. =item B<18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate>
  203. the passed certificate is self signed and the same certificate cannot be found in the list of
  204. trusted certificates.
  205. =item B<19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain>
  206. the certificate chain could be built up using the untrusted certificates but the root could not
  207. be found locally.
  208. =item B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate>
  209. the issuer certificate could not be found: this occurs if the issuer
  210. certificate of an untrusted certificate cannot be found.
  211. =item B<21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate>
  212. no signatures could be verified because the chain contains only one certificate and it is not
  213. self signed.
  214. =item B<22 X509_V_ERR_CERT_CHAIN_TOO_LONG: certificate chain too long>
  215. the certificate chain length is greater than the supplied maximum depth. Unused.
  216. =item B<23 X509_V_ERR_CERT_REVOKED: certificate revoked>
  217. the certificate has been revoked.
  218. =item B<24 X509_V_ERR_INVALID_CA: invalid CA certificate>
  219. a CA certificate is invalid. Either it is not a CA or its extensions are not consistent
  220. with the supplied purpose.
  221. =item B<25 X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint exceeded>
  222. the basicConstraints pathlength parameter has been exceeded.
  223. =item B<26 X509_V_ERR_INVALID_PURPOSE: unsupported certificate purpose>
  224. the supplied certificate cannot be used for the specified purpose.
  225. =item B<27 X509_V_ERR_CERT_UNTRUSTED: certificate not trusted>
  226. the root CA is not marked as trusted for the specified purpose.
  227. =item B<28 X509_V_ERR_CERT_REJECTED: certificate rejected>
  228. the root CA is marked to reject the specified purpose.
  229. =item B<29 X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch>
  230. the current candidate issuer certificate was rejected because its subject name
  231. did not match the issuer name of the current certificate. Only displayed when
  232. the B<-issuer_checks> option is set.
  233. =item B<30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch>
  234. the current candidate issuer certificate was rejected because its subject key
  235. identifier was present and did not match the authority key identifier current
  236. certificate. Only displayed when the B<-issuer_checks> option is set.
  237. =item B<31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch>
  238. the current candidate issuer certificate was rejected because its issuer name
  239. and serial number was present and did not match the authority key identifier
  240. of the current certificate. Only displayed when the B<-issuer_checks> option is set.
  241. =item B<32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing>
  242. the current candidate issuer certificate was rejected because its keyUsage extension
  243. does not permit certificate signing.
  244. =item B<50 X509_V_ERR_APPLICATION_VERIFICATION: application verification failure>
  245. an application specific error. Unused.
  246. =back
  247. =head1 BUGS
  248. Although the issuer checks are a considerably improvement over the old technique they still
  249. suffer from limitations in the underlying X509_LOOKUP API. One consequence of this is that
  250. trusted certificates with matching subject name must either appear in a file (as specified by the
  251. B<-CAfile> option) or a directory (as specified by B<-CApath>. If they occur in both then only
  252. the certificates in the file will be recognised.
  253. Previous versions of OpenSSL assume certificates with matching subject name are identical and
  254. mishandled them.
  255. Previous versions of this documentation swapped the meaning of the
  256. B<X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT> and
  257. B<20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY> error codes.
  258. =head1 SEE ALSO
  259. L<x509(1)|x509(1)>
  260. =cut