verify(1ssl) - phpMan

VERIFY(1) OpenSSL VERIFY(1)

NAME
verify - Utility to verify certificates.

SYNOPSIS
openssl verify [-CApath directory] [-CAfile file] [-trusted_first] [-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]

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.

-trusted_first
Use certificates in CA file or CA directory before the certificates in the untrusted
file when building the trust chain to verify certificates. This is mainly useful in
environments with Bridge CA or Cross-Certified CAs.

-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.

-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.

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.