verify(1)
VERIFY(1) 0.9.6h (2001-10-08) VERIFY(1)
NAME
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.
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- marks 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 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.
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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.
certificate
2 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: unable to get issuer
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the issuer certificate could not be found: this occurs
if the issuer certificate of an untrusted certificate
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.
certificate's signature
4 X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE: unable to
decrypt
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.
CRL's signature
5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to
decrypt
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.
issuer public key
6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to
decode
the public key in the certificate SubjectPublicKeyInfo
could not be read.
failure
7 X509_V_ERR_CERT_SIGNATURE_FAILURE: certificate signature
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_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. Unused.
12 X509_V_ERR_CRL_HAS_EXPIRED: CRL has expired
the CRL has expired. Unused.
certificate's notBefore field
13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error
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in
the certificate notBefore field contains an invalid
time.
certificate's notAfter field
14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in
the certificate notAfter field contains an invalid time.
CRL's lastUpdate field
15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error
in
the CRL lastUpdate field contains an invalid time.
Unused.
CRL's nextUpdate field
16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error
in
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.
certificate
18 X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: self signed
the passed certificate is self signed and the same
certificate cannot be found in the list of trusted
certificates.
in certificate chain
19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed
certificate
the certificate chain could be built up using the
untrusted certificates but the root could not be found
locally.
local issuer certificate
20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to
get
the issuer certificate of a locally looked up
certificate could not be found. This normally means the
list of trusted certificates is not complete.
the first certificate
21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to
verify
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
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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
purpose.
exceeded
25 X509_V_ERR_PATH_LENGTH_EXCEEDED: path length constraint
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.
identifier mismatch
30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key
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.
serial number mismatch
31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and
issuer
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.
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certificate signing
32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not
include
the current candidate issuer certificate was rejected
because its keyUsage extension does not permit
certificate signing.
failure
50 X509_V_ERR_APPLICATION_VERIFICATION: application
verification
an application specific error. Unused.
BUGS
Although the issuer checks are a considerably 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.
SEE ALSO
x509(1)
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