NAME
verify - Utility to verify certificates.
LIBRARY
libcrypto, -lcrypto
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] [
-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
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.
SEE ALSO
openssl_x509(1)
HISTORY
The -no_alt_chains options was first added to OpenSSL 1.0.2b.