verify






openssl−verify, verify − Utility to verify certificates.

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] [−allow_proxy_certs] [−untrusted file]
[−help] [−issuer_checks] [−trusted file] [−verbose] []
[certificates]

The verify command verifies certificate chains.



−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









                             ‐2‐


    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.










                             ‐3‐


−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. Certificates must be in PEM format.

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










                             ‐4‐


     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.











                             ‐5‐


     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.

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









                             ‐6‐


    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









                             ‐7‐


    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









                             ‐8‐


    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.

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.

x509(1)

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