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verify(1ssl)
NAME
verify - Utility to verify certificates
SYNOPSIS
openssl verify [-CApath directory] [-CAfile filename] [-purpose purpose]
[-untrusted filename] [-help] [-issuer_checks] [-verbose] [-]
[certificates]
DESCRIPTION
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. Under UNIX the c_rehash script will automatically create
symbolic links to a directory of certificates. (Hash is the hashed
certificate subject name. See the -hash option of the x509
command.)
-CAfile filename
A file of trusted certificates. The file should contain multiple
certificates in PEM format concatenated together.
-untrusted filename
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
Prints extra information about the operations being performed.
-issuer_checks
Prints 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.
- 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.
DESCRIPTION
The verify utility verifies certificate chains. It uses the same functions
as the internal SSL and S/MIME verification. However, 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. Usually
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.
First, a certificate chain is built, starting from the supplied certificate
and ending in the root CA. It is an error if the whole chain cannot be
built. The chain is built by looking up the issuer's 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 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 issuer's 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.
1. 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.
2. 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.
3. 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.
4. 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 the certificate is considered
valid. If any operation fails then the certificate is not valid.
RESTRICTIONS
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 recognized.
Previous versions of OpenSSL assume certificates with matching subject name
are identical and mishandled them.
ERRORS
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 the 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.
A 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 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.
signature
5 X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE: unable to decrypt CRL's
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.
public key
6 X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY: unable to decode issuer
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_CERT_HAS_EXPIRED: certificate has expired
The certificate has expired. The notAfter date is before 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. 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.
notBefore field
13 X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: format error in certificate's
The certificate notBefore field contains an invalid time.
notAfter field
14 X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: format error in certificate's
The certificate notAfter field contains an invalid time.
lastUpdate field
15 X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD: format error in CRL's
The CRL lastUpdate field contains an invalid time. Unused.
nextUpdate field
16 X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD: format error in CRL's
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.
certificate chain
19 X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in
The certificate chain could be built up using the untrusted
certificates but the root could not be found locally.
certificate
20 X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: unable to get local issuer
The issuer certificate of a locally looked up certificate could not
be found. This normally means the list of trusted certificates is
not complete.
certificate
21 X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE: unable to verify the first
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 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. This is only displayed when the -issuer_checks option
is set.
mismatch
30 X509_V_ERR_AKID_SKID_MISMATCH: authority and subject key identifier
The current candidate issuer certificate was rejected because its
subject key identifier was present and did not match the authority
key identifier current certificate. This is only displayed when the
-issuer_checks option is set.
mismatch
31 X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH: authority and issuer serial number
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. This is only
displayed when the -issuer_checks option is set.
signing
32 X509_V_ERR_KEYUSAGE_NO_CERTSIGN:key usage does not include certificate
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.
SEE ALSO
Commands: x509(1ssl)
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