/usr/man2/cat.1/verify.1.Z(/usr/man2/cat.1/verify.1.Z)

NAME

       openssl-verify, 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] [-pol-
       icy_check] [-explicit_policy] [-inhibit_any] [-inhibit_map]
       [-x509_strict] [-extended_crl] [-use_deltas] [-policy_print]
       [-no_alt_chains] [-allow_proxy_certs] [-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 speci-
           fied, verify will not consider certificate purpose during chain
           verification.  Currently accepted uses are sslclient, sslserver,
           nssslserver, smimesign, smimeencrypt. See the VERIFY OPERATION sec-
           tion 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 certifi-
           cate 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.

       -allow_proxy_certs
           Allow the verification of proxy certificates.

       -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. Cer-
           tificates 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 cer-
       tificate 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 cer-
       tificate whose subject name matched the issuer of the current certifi-
       cate 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 exten-
       sions for consistency with the supplied purpose. If the -purpose option
       is not included then no checks are done. The supplied or "leaf" cer-
       tificate 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 signa-
       tures 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 cryp-
       tic. 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 fol-
       lowed 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 certifi-
       cate
           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 cer-
       tificate'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 certifi-
       cate's notBefore field
           the certificate notBefore field contains an invalid time.

       14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certifi-
       cate'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 hap-
           pen.

       18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed certificate
           the passed certificate is self signed and the same certificate can-
           not 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 cer-
           tificates 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 exten-
           sions 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 certifi-
           cate. 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 certifi-
       cate 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 fail-
       ure
           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 recog-
       nised.

       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.

1.0.2t                            2019-09-10                         VERIFY(1)
See also openssl-verify(1)