verify - Utility to verify certificates.
SYNOPSIS
openssl verify [-CApath directory] [-CAfile file]
[-purpose purpose] [-untrusted file] [-help]
[-issuer_checks] [-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.
-untrusted file
A file of untrusted certificates. The file should
contain multiple certificates
-purpose purpose
the intended use for the certificate. Without this
option no chain verification will be done. Currently
accepted uses are sslclient, sslserver, nssslserver,
smimesign, smimeencrypt. See the VERIFY OPERATION
section for more information.
-help
prints 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. However the presence of rejection messages
does not itself imply that anything is wrong: during
the normal verify process several rejections may take
place.
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 certificate
filenames are included then an attempt is made to read
a certificate from standard input. They should all 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
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 could not be found: this occurs
cannot be found.
3 X509_V_ERR_UNABLE_TO_GET_CRL unable to get certificate
CRL
the CRL of a certificate could not be found. Unused.
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. Unused.
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_CRL_NOT_YET_VALID: CRL is not yet valid
the CRL is not yet valid. Unused.
11 X509_V_ERR_CERT_HAS_EXPIRED: Certificate has expired
the certificate has expired: that is the notAfter date
is before the current time.
12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired
the CRL has expired. Unused.
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.
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.
Unused.
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.
Unused.
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 of a locally looked up
certificate could not be found. This normally means
the list of trusted certificates is not complete.
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. Unused.
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
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 considerably improvement
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.
SEE ALSO
x509(1)
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