This specifies the input filename to read a certificate from or standard input if this option is not specified.

When signing a certificate, preserve the "notBefore" and "notAfter" dates instead of adjusting them to current time and duration. Cannot be used with the -days option.

[-rand files] [-writerand file]

Trust Settings

A trusted certificate is an ordinary certificate which has several additional pieces of information attached to it such as the permitted and prohibited uses of the certificate and an "alias".

Normally when a certificate is being verified at least one certificate must be "trusted". By default a trusted certificate must be stored locally and must be a root CA: any certificate chain ending in this CA is then usable for any purpose.

Trust settings currently are only used with a root CA. They allow a finer control over the purposes the root CA can be used for. For example a CA may be trusted for SSL client but not SSL server use.

Output a trusted certificate rather than an ordinary. An ordinary or trusted certificate can be input but by default an ordinary certificate is output and any trust settings are discarded. With the -trustout option a trusted certificate is output. A trusted certificate is automatically output if any trust settings are modified.

Delete any extensions from a certificate. This option is used when a certificate is being created from another certificate (for example with the -signkey or the -CA options). Normally all extensions are retained.

Specifies the number of days to make a certificate valid for. The default is 30 days. Cannot be used with the -preserve_dates option.

Generate a certificate from scratch, not using an input certificate or certificate request. So the -in option must not be used in this case. Instead, the -subj and <-force_pubkey> options need to be given.

Display the contents of a certificate:

 openssl x509 -in cert.pem -noout -text

Display the "Subject Alternative Name" extension of a certificate:

 openssl x509 -in cert.pem -noout -ext subjectAltName

Display more extensions of a certificate:

 openssl x509 -in cert.pem -noout -ext subjectAltName,nsCertType

Display the certificate serial number:

 openssl x509 -in cert.pem -noout -serial

Display the certificate subject name:

 openssl x509 -in cert.pem -noout -subject

Display the certificate subject name in RFC2253 form:

 openssl x509 -in cert.pem -noout -subject -nameopt RFC2253

Display the certificate subject name in oneline form on a terminal supporting UTF8:

 openssl x509 -in cert.pem -noout -subject -nameopt oneline,-esc_msb

Display the certificate SHA1 fingerprint:

 openssl x509 -sha1 -in cert.pem -noout -fingerprint

Convert a certificate from PEM to DER format:

 openssl x509 -in cert.pem -inform PEM -out cert.der -outform DER

Convert a certificate to a certificate request:

 openssl x509 -x509toreq -in cert.pem -out req.pem -signkey key.pem

Convert a certificate request into a self signed certificate using extensions for a CA:

 openssl x509 -req -in careq.pem -extfile openssl.cnf -extensions v3_ca \
        -signkey key.pem -out cacert.pem

Sign a certificate request using the CA certificate above and add user certificate extensions:

 openssl x509 -req -in req.pem -extfile openssl.cnf -extensions v3_usr \
        -CA cacert.pem -CAkey key.pem -CAcreateserial

Set a certificate to be trusted for SSL client use and change set its alias to "Steve's Class 1 CA"

 openssl x509 -in cert.pem -addtrust clientAuth \
        -setalias "Steve's Class 1 CA" -out trust.pem

NOTES

The conversion to UTF8 format used with the name options assumes that T61Strings use the ISO8859-1 character set. This is wrong but Netscape and MSIE do this as do many certificates. So although this is incorrect it is more likely to display the majority of certificates correctly.

The -email option searches the subject name and the subject alternative name extension. Only unique email addresses will be printed out: it will not print the same address more than once.

CERTIFICATE EXTENSIONS

The -purpose option checks the certificate extensions and determines what the certificate can be used for. The actual checks done are rather complex and include various hacks and workarounds to handle broken certificates and software.

The same code is used when verifying untrusted certificates in chains so this section is useful if a chain is rejected by the verify code.

The basicConstraints extension CA flag is used to determine whether the certificate can be used as a CA. If the CA flag is true then it is a CA, if the CA flag is false then it is not a CA. All CAs should have the CA flag set to true.

If the basicConstraints extension is absent then the certificate is considered to be a "possible CA" other extensions are checked according to the intended use of the certificate. A warning is given in this case because the certificate should really not be regarded as a CA: however it is allowed to be a CA to work around some broken software.

If the certificate is a V1 certificate (and thus has no extensions) and it is self signed it is also assumed to be a CA but a warning is again given: this is to work around the problem of Verisign roots which are V1 self signed certificates.

If the keyUsage extension is present then additional restraints are made on the uses of the certificate. A CA certificate must have the keyCertSign bit set if the keyUsage extension is present.

The extended key usage extension places additional restrictions on the certificate uses. If this extension is present (whether critical or not) the key can only be used for the purposes specified.

A complete description of each test is given below. The comments about basicConstraints and keyUsage and V1 certificates above apply to all CA certificates.

SSL Client

The extended key usage extension must be absent or include the "web client authentication" OID. keyUsage must be absent or it must have the digitalSignature bit set. Netscape certificate type must be absent or it must have the SSL client bit set.

SSL Client CA

The extended key usage extension must be absent or include the "web client authentication" OID. Netscape certificate type must be absent or it must have the SSL CA bit set: this is used as a work around if the basicConstraints extension is absent.

SSL Server

The extended key usage extension must be absent or include the "web server authentication" and/or one of the SGC OIDs. keyUsage must be absent or it must have the digitalSignature, the keyEncipherment set or both bits set. Netscape certificate type must be absent or have the SSL server bit set.

SSL Server CA

The extended key usage extension must be absent or include the "web server authentication" and/or one of the SGC OIDs. Netscape certificate type must be absent or the SSL CA bit must be set: this is used as a work around if the basicConstraints extension is absent.

Netscape SSL Server

For Netscape SSL clients to connect to an SSL server it must have the keyEncipherment bit set if the keyUsage extension is present. This isn't always valid because some cipher suites use the key for digital signing. Otherwise it is the same as a normal SSL server.

Common S/MIME Client Tests

The extended key usage extension must be absent or include the "email protection" OID. Netscape certificate type must be absent or should have the S/MIME bit set. If the S/MIME bit is not set in Netscape certificate type then the SSL client bit is tolerated as an alternative but a warning is shown: this is because some Verisign certificates don't set the S/MIME bit.

S/MIME Signing

In addition to the common S/MIME client tests the digitalSignature bit or the nonRepudiation bit must be set if the keyUsage extension is present.

S/MIME Encryption

In addition to the common S/MIME tests the keyEncipherment bit must be set if the keyUsage extension is present.

S/MIME CA

The extended key usage extension must be absent or include the "email protection" OID. Netscape certificate type must be absent or must have the S/MIME CA bit set: this is used as a work around if the basicConstraints extension is absent.

CRL Signing

The keyUsage extension must be absent or it must have the CRL signing bit set.

CRL Signing CA

The normal CA tests apply. Except in this case the basicConstraints extension must be present.

BUGS

Extensions in certificates are not transferred to certificate requests and vice versa.

It is possible to produce invalid certificates or requests by specifying the wrong private key or using inconsistent options in some cases: these should be checked.

There should be options to explicitly set such things as start and end dates rather than an offset from the current time.

SEE ALSO