openssl-verify, verify - Utility to verify certificates
openssl verify [-help] [-CAfile file]
[-CApath directory] [-no-CAfile] [-no-CApath]
[-allow_proxy_certs] [-attime timestamp]
[-check_ss_sig] [-CRLfile file] [-crl_download]
[-crl_check] [-crl_check_all] [-engine id]
[-explicit_policy] [-extended_crl] [-ignore_critical]
[-inhibit_any] [-inhibit_map] [-nameopt option]
[-no_check_time] [-partial_chain] [-policy arg]
[-policy_check] [-policy_print] [-purpose purpose]
[-suiteB_128] [-suiteB_128_only] [-suiteB_192]
[-trusted_first] [-no_alt_chains] [-untrusted file]
[-trusted file] [-use_deltas] [-verbose]
[-auth_level level] [-verify_depth num] [-verify_email
email] [-verify_hostname hostname] [-verify_ip ip]
[-verify_name name] [-x509_strict] [-show_chain]
The verify command verifies certificate chains.
- Print out a usage message.
- A file of trusted certificates. The file should contain one or more
certificates in PEM format.
- 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.
- Do not load the trusted CA certificates from the default file
- Do not load the trusted CA certificates from the default directory
- Allow the verification of proxy certificates.
- 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).
- Verify the signature of the last certificate in a chain if the certificate
is supposedly self-signed. This is prohibited and will result in an error
if it is a non-conforming CA certificate with key usage restrictions not
including the keyCertSign bit. This verification is disabled by default
because it doesn't add any security.
- The file should contain one or more CRLs in PEM format. This option
can be specified more than once to include CRLs from multiple
- Attempt to download CRL information for this certificate.
- Checks end entity certificate validity by attempting to look up a valid
CRL. If a valid CRL cannot be found an error occurs.
- Checks the validity of all certificates in the chain by attempting
to look up valid CRLs.
- -engine id
- Specifying an engine id will cause verify(1) to attempt to
load the specified engine. The engine will then be set as the default for
all its supported algorithms. If you want to load certificates or CRLs
that require engine support via any of the -trusted,
-untrusted or -CRLfile options, the -engine option
must be specified before those options.
- Set policy variable require-explicit-policy (see RFC5280).
- Enable extended CRL features such as indirect CRLs and alternate CRL
- 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.
- Set policy variable inhibit-any-policy (see RFC5280).
- Set policy variable inhibit-policy-mapping (see RFC5280).
- Option which determines how the subject or issuer names are displayed. The
option argument can be a single option or multiple options
separated by commas. Alternatively the -nameopt switch may be used
more than once to set multiple options. See the x509(1) manual page
- This option suppresses checking the validity period of certificates and
CRLs against the current time. If option -attime timestamp is used
to specify a verification time, the check is not suppressed.
- Allow verification to succeed even if a complete chain cannot be
built to a self-signed trust-anchor, provided it is possible to construct
a chain to a trusted certificate that might not be self-signed.
- 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.
- Enables certificate policy processing.
- Print out diagnostics related to policy processing.
- 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
- Enable the Suite B mode operation at 128 bit Level of Security, 128 bit or
192 bit, or only 192 bit Level of Security respectively. See RFC6460 for
details. In particular the supported signature algorithms are reduced to
support only ECDSA and SHA256 or SHA384 and only the elliptic curves P-256
- When constructing the certificate chain, use the trusted certificates
specified via -CAfile, -CApath or -trusted before any
certificates specified via -untrusted. This can be useful in
environments with Bridge or Cross-Certified CAs. As of OpenSSL 1.1.0 this
option is on by default and cannot be disabled.
- By default, unless -trusted_first is specified, when building a
certificate chain, if the first certificate chain found is not trusted,
then OpenSSL will attempt to replace untrusted issuer certificates with
certificates from the trust store to see if an alternative chain can be
found that is trusted. As of OpenSSL 1.1.0, with -trusted_first
always on, this option has no effect.
- A file of additional untrusted certificates (intermediate issuer
CAs) used to construct a certificate chain from the subject certificate to
a trust-anchor. The file should contain one or more certificates in
PEM format. This option can be specified more than once to include
untrusted certificates from multiple files.
- A file of trusted certificates, which must be self-signed, unless
the -partial_chain option is specified. The file contains
one or more certificates in PEM format. With this option, no additional
(e.g., default) certificate lists are consulted. That is, the only
trust-anchors are those listed in file. This option can be
specified more than once to include trusted certificates from multiple
files. This option implies the -no-CAfile and
-no-CApath options. This option cannot be used in combination with
either of the -CAfile or -CApath options.
- Enable support for delta CRLs.
- Print extra information about the operations being performed.
- Set the certificate chain authentication security level to level.
The authentication security level determines the acceptable signature and
public key strength when verifying certificate chains. For a certificate
chain to validate, the public keys of all the certificates must meet the
specified security level. The signature algorithm security level is
enforced for all the certificates in the chain except for the chain's
trust anchor, which is either directly trusted or validated by
means other than its signature. See SSL_CTX_set_security_level(3)
for the definitions of the available levels. The default security level is
-1, or "not set". At security level 0 or lower all algorithms
are acceptable. Security level 1 requires at least 80-bit-equivalent
security and is broadly interoperable, though it will, for example, reject
MD5 signatures or RSA keys shorter than 1024 bits.
- Limit the certificate chain to num intermediate CA certificates. A
maximal depth chain can have up to num+2 certificates, since
neither the end-entity certificate nor the trust-anchor certificate count
against the -verify_depth limit.
- Verify if the email matches the email address in Subject
Alternative Name or the email in the subject Distinguished Name.
- Verify if the hostname matches DNS name in Subject Alternative Name
or Common Name in the subject certificate.
- Verify if the ip matches the IP address in Subject Alternative Name
of the subject certificate.
- Use default verification policies like trust model and required
certificate policies identified by name. The trust model determines
which auxiliary trust or reject OIDs are applicable to verifying the given
certificate chain. See the -addtrust and -addreject options
of the x509(1) command-line utility. Supported policy names
include: default, pkcs7, smime_sign,
ssl_client, ssl_server. These mimics the combinations of
purpose and trust settings used in SSL, CMS and S/MIME. As of OpenSSL
1.1.0, the trust model is inferred from the purpose when not specified, so
the -verify_name options are functionally equivalent to the
corresponding -purpose settings.
- For strict X.509 compliance, disable non-compliant workarounds for broken
- Display information about the certificate chain that has been built (if
successful). Certificates in the chain that came from the untrusted list
will be flagged as "untrusted".
- 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 -.
- 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.
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
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. After 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
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 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. For each element in the chain, including the root CA certificate, the
validity period as specified by the
"notAfter" fields is checked against the
current system time. The -attime flag may be used to use a reference
time other than "now." The certificate signature is checked as
well (except for the signature of the typically self-signed root CA
certificate, which is verified only if the -check_ss_sig option is
If all operations complete successfully then certificate is
considered valid. If any operation fails then the certificate is not
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
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_LOCALLY error codes.
The -show_chain option was added in OpenSSL 1.1.0.
The -issuer_checks option is deprecated as of OpenSSL 1.1.0
and is silently ignored.
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Licensed under the OpenSSL license (the "License"). You
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