Provided by: openssl_1.0.2g-1ubuntu4.20_amd64 
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.