NAME

       verify - Utility to verify certificates.

SYNOPSIS

       openssl verify [-CApath directory] [-CAfile file] [-purpose purpose] [-policy arg]
       [-ignore_critical] [-attime timestamp] [-check_ss_sig] [-crlfile file] [-crl_download]
       [-crl_check] [-crl_check_all] [-policy_check] [-explicit_policy] [-inhibit_any]
       [-inhibit_map] [-x509_strict] [-extended_crl] [-use_deltas] [-policy_print]
       [-no_alt_chains] [-untrusted file] [-help] [-issuer_checks] [-trusted file] [-verbose] [-]
       [certificates]

DESCRIPTION

       The verify command verifies certificate chains.

COMMAND OPTIONS

       -CApath directory
           A directory of trusted certificates. The certificates should have names of the form:
           hash.0 or have symbolic links to them of this form ("hash" is the hashed certificate
           subject name: see the -hash option of the x509 utility). Under Unix the c_rehash
           script will automatically create symbolic links to a directory of certificates.

       -CAfile file A file of trusted certificates. The file should contain multiple certificates
       in PEM format concatenated together.
       -attime timestamp
           Perform validation checks using time specified by timestamp and not current system
           time. timestamp is the number of seconds since 01.01.1970 (UNIX time).

       -check_ss_sig
           Verify the signature on the self-signed root CA. This is disabled by default because
           it doesn't add any security.

       -crlfile file
           File containing one or more CRL's (in PEM format) to load.

       -crl_download
           Attempt to download CRL information for this certificate.

       -crl_check
           Checks end entity certificate validity by attempting to look up a valid CRL.  If a
           valid CRL cannot be found an error occurs.

       -untrusted file
           A file of untrusted certificates. The file should contain multiple certificates in PEM
           format concatenated together.

       -purpose purpose
           The intended use for the certificate. If this option is not specified, verify will not
           consider certificate purpose during chain verification.  Currently accepted uses are
           sslclient, sslserver, nssslserver, smimesign, smimeencrypt. See the VERIFY OPERATION
           section for more information.

       -help
           Print out a usage message.

       -verbose
           Print extra information about the operations being performed.

       -issuer_checks
           Print out diagnostics relating to searches for the issuer certificate of the current
           certificate. This shows why each candidate issuer certificate was rejected. The
           presence of rejection messages does not itself imply that anything is wrong; during
           the normal verification process, several rejections may take place.

       -policy arg
           Enable policy processing and add arg to the user-initial-policy-set (see RFC5280). The
           policy arg can be an object name an OID in numeric form.  This argument can appear
           more than once.

       -policy_check
           Enables certificate policy processing.

       -explicit_policy
           Set policy variable require-explicit-policy (see RFC5280).

       -inhibit_any
           Set policy variable inhibit-any-policy (see RFC5280).

       -inhibit_map
           Set policy variable inhibit-policy-mapping (see RFC5280).

       -no_alt_chains
           When building a certificate chain, if the first certificate chain found is not
           trusted, then OpenSSL will continue to check to see if an alternative chain can be
           found that is trusted. With this option that behaviour is suppressed so that only the
           first chain found is ever used. Using this option will force the behaviour to match
           that of previous OpenSSL versions.

       -trusted file
           A file of additional trusted certificates. The file should contain multiple
           certificates in PEM format concatenated together.

       -policy_print
           Print out diagnostics related to policy processing.

       -crl_check
           Checks end entity certificate validity by attempting to look up a valid CRL.  If a
           valid CRL cannot be found an error occurs.

       -crl_check_all
           Checks the validity of all certificates in the chain by attempting to look up valid
           CRLs.

       -ignore_critical
           Normally if an unhandled critical extension is present which is not supported by
           OpenSSL the certificate is rejected (as required by RFC5280).  If this option is set
           critical extensions are ignored.

       -x509_strict
           For strict X.509 compliance, disable non-compliant workarounds for broken
           certificates.

       -extended_crl
           Enable extended CRL features such as indirect CRLs and alternate CRL signing keys.

       -use_deltas
           Enable support for delta CRLs.

       -check_ss_sig
           Verify the signature on the self-signed root CA. This is disabled by default because
           it doesn't add any security.

       -   Indicates the last option. All arguments following this are assumed to be certificate
           files. This is useful if the first certificate filename begins with a -.

       certificates
           One or more certificates to verify. If no certificates are given, verify will attempt
           to read a certificate from standard input. Certificates must be in PEM format.

VERIFY OPERATION

       The verify program uses the same functions as the internal SSL and S/MIME verification,
       therefore this description applies to these verify operations too.

       There is one crucial difference between the verify operations performed by the verify
       program: wherever possible an attempt is made to continue after an error whereas normally
       the verify operation would halt on the first error. This allows all the problems with a
       certificate chain to be determined.

       The verify operation consists of a number of separate steps.

       Firstly a certificate chain is built up starting from the supplied certificate and ending
       in the root CA. It is an error if the whole chain cannot be built up. The chain is built
       up by looking up the issuers certificate of the current certificate. If a certificate is
       found which is its own issuer it is assumed to be the root CA.

       The process of 'looking up the issuers certificate' itself involves a number of steps. In
       versions of OpenSSL before 0.9.5a the first certificate whose subject name matched the
       issuer of the current certificate was assumed to be the issuers certificate. In OpenSSL
       0.9.6 and later all certificates whose subject name matches the issuer name of the current
       certificate are subject to further tests. The relevant authority key identifier components
       of the current certificate (if present) must match the subject key identifier (if present)
       and issuer and serial number of the candidate issuer, in addition the keyUsage extension
       of the candidate issuer (if present) must permit certificate signing.

       The lookup first looks in the list of untrusted certificates and if no match is found the
       remaining lookups are from the trusted certificates. The root CA is always looked up in
       the trusted certificate list: if the certificate to verify is a root certificate then an
       exact match must be found in the trusted list.

       The second operation is to check every untrusted certificate's extensions for consistency
       with the supplied purpose. If the -purpose option is not included then no checks are done.
       The supplied or "leaf" certificate must have extensions compatible with the supplied
       purpose and all other certificates must also be valid CA certificates. The precise
       extensions required are described in more detail in the CERTIFICATE EXTENSIONS section of
       the x509 utility.

       The third operation is to check the trust settings on the root CA. The root CA should be
       trusted for the supplied purpose. For compatibility with previous versions of SSLeay and
       OpenSSL a certificate with no trust settings is considered to be valid for all purposes.

       The final operation is to check the validity of the certificate chain. The validity period
       is checked against the current system time and the notBefore and notAfter dates in the
       certificate. The certificate signatures are also checked at this point.

       If all operations complete successfully then certificate is considered valid. If any
       operation fails then the certificate is not valid.

DIAGNOSTICS

       When a verify operation fails the output messages can be somewhat cryptic. The general
       form of the error message is:

        server.pem: /C=AU/ST=Queensland/O=CryptSoft Pty Ltd/CN=Test CA (1024 bit)
        error 24 at 1 depth lookup:invalid CA certificate

       The first line contains the name of the certificate being verified followed by the subject
       name of the certificate. The second line contains the error number and the depth. The
       depth is number of the certificate being verified when a problem was detected starting
       with zero for the certificate being verified itself then 1 for the CA that signed the
       certificate and so on. Finally a text version of the error number is presented.

       An exhaustive list of the error codes and messages is shown below, this also includes the
       name of the error code as defined in the header file x509_vfy.h Some of the error codes
       are defined but never returned: these are described as "unused".

       0 X509_V_OK: ok
           the operation was successful.

       2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer certificate
           the issuer certificate of a looked up certificate could not be found. This normally
           means the list of trusted certificates is not complete.

       3 X509_V_ERR_UNABLE_TO_GET_CRL: unable to get certificate CRL
           the CRL of a certificate could not be found.

       4 X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to decrypt certificate's signature
           the certificate signature could not be decrypted. This means that the actual signature
           value could not be determined rather than it not matching the expected value, this is
           only meaningful for RSA keys.

       5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's signature
           the CRL signature could not be decrypted: this means that the actual signature value
           could not be determined rather than it not matching the expected value. Unused.

       6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer public key
           the public key in the certificate SubjectPublicKeyInfo could not be read.

       7 X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature failure
           the signature of the certificate is invalid.

       8 X509_V_ERR_CRL_SIGNATURE_FAILURE: CRL signature failure
           the signature of the certificate is invalid.

       9 X509_V_ERR_CERT_NOT_YET_VALID: certificate is not yet valid
           the certificate is not yet valid: the notBefore date is after the current time.

       10 X509_V_ERR_CERT_HAS_EXPIRED: certificate has expired
           the certificate has expired: that is the notAfter date is before the current time.

       11 X509_V_ERR_CRL_NOT_YET_VALID: CRL is not yet valid
           the CRL is not yet valid.

       12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired
           the CRL has expired.

       13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's notBefore
       field
           the certificate notBefore field contains an invalid time.

       14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's notAfter field
           the certificate notAfter field contains an invalid time.

       15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's lastUpdate field
           the CRL lastUpdate field contains an invalid time.

       16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's nextUpdate field
           the CRL nextUpdate field contains an invalid time.

       17 X509_V_ERR_OUT_OF_MEM: out of memory
           an error occurred trying to allocate memory. This should never happen.

       18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate
           the passed certificate is self signed and the same certificate cannot be found in the
           list of trusted certificates.

       19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain
           the certificate chain could be built up using the untrusted certificates but the root
           could not be found locally.

       20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer certificate
           the issuer certificate could not be found: this occurs if the issuer certificate of an
           untrusted certificate cannot be found.

       21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first certificate
           no signatures could be verified because the chain contains only one certificate and it
           is not self signed.

       22 X509_V_ERR_CERT_CHAIN_TOO_LONG: certificate chain too long
           the certificate chain length is greater than the supplied maximum depth. Unused.

       23 X509_V_ERR_CERT_REVOKED: certificate revoked
           the certificate has been revoked.

       24 X509_V_ERR_INVALID_CA: invalid CA certificate
           a CA certificate is invalid. Either it is not a CA or its extensions are not
           consistent with the supplied purpose.

       25 X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint exceeded
           the basicConstraints pathlength parameter has been exceeded.

       26 X509_V_ERR_INVALID_PURPOSE: unsupported certificate purpose
           the supplied certificate cannot be used for the specified purpose.

       27 X509_V_ERR_CERT_UNTRUSTED: certificate not trusted
           the root CA is not marked as trusted for the specified purpose.

       28 X509_V_ERR_CERT_REJECTED: certificate rejected
           the root CA is marked to reject the specified purpose.

       29 X509_V_ERR_SUBJECT_ISSUER_MISMATCH: subject issuer mismatch
           the current candidate issuer certificate was rejected because its subject name did not
           match the issuer name of the current certificate. Only displayed when the
           -issuer_checks option is set.

       30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier mismatch
           the current candidate issuer certificate was rejected because its subject key
           identifier was present and did not match the authority key identifier current
           certificate. Only displayed when the -issuer_checks option is set.

       31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number mismatch
           the current candidate issuer certificate was rejected because its issuer name and
           serial number was present and did not match the authority key identifier of the
           current certificate. Only displayed when the -issuer_checks option is set.

       32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate signing
           the current candidate issuer certificate was rejected because its keyUsage extension
           does not permit certificate signing.

       50 X509_V_ERR_APPLICATION_VERIFICATION: application verification failure
           an application specific error. Unused.

BUGS

       Although the issuer checks are a considerable improvement over the old technique they
       still suffer from limitations in the underlying X509_LOOKUP API. One consequence of this
       is that trusted certificates with matching subject name must either appear in a file (as
       specified by the -CAfile option) or a directory (as specified by -CApath. If they occur in
       both then only the certificates in the file will be recognised.

       Previous versions of OpenSSL assume certificates with matching subject name are identical
       and mishandled them.

       Previous versions of this documentation swapped the meaning of the
       X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT and 20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY
       error codes.

SEE ALSO

       x509(1)

HISTORY

       The -no_alt_chains options was first added to OpenSSL 1.0.2b.