4.5.2 CSR and certificate creation

Please notice: The immediate creation of certificates is only supported by GnuPG version 2.1 or later. With a 2.0 version you may only create a CSR.

The command --gen-key may be used along with the option --batch to either create a certificate signing request (CSR) or an X.509 certificate. The is controlled by a parameter file; the format of this file is as follows:

• Text only, line length is limited to about 1000 characters.
• UTF-8 encoding must be used to specify non-ASCII characters.
• Empty lines are ignored.
• Leading and trailing while space is ignored.
• A hash sign as the first non white space character indicates a comment line.
• Control statements are indicated by a leading percent sign, the arguments are separated by white space from the keyword.
• Parameters are specified by a keyword, followed by a colon. Arguments are separated by white space.
• The first parameter must be ‘Key-Type’, control statements may be placed anywhere.
• The order of the parameters does not matter except for ‘Key-Type’ which must be the first parameter. The parameters are only used for the generated CSR/certificate; parameters from previous sets are not used. Some syntactically checks may be performed.
• Key generation takes place when either the end of the parameter file is reached, the next ‘Key-Type’ parameter is encountered or at the control statement ‘%commit’ is encountered.

Control statements:

%echo text

Print text as diagnostic.

%dry-run

Suppress actual key generation (useful for syntax checking).

%commit

Perform the key generation. Note that an implicit commit is done at the next Key-Type parameter.

General Parameters:

Key-Type: algo

Starts a new parameter block by giving the type of the primary key. The algorithm must be capable of signing. This is a required parameter. The only supported value for algo is ‘rsa’.

Key-Length: nbits

The requested length of a generated key in bits. Defaults to 2048.

Key-Grip: hexstring

This is optional and used to generate a CSR or certificatet for an already existing key. Key-Length will be ignored when given.

Key-Usage: usage-list

Space or comma delimited list of key usage, allowed values are ‘encrypt’, ‘sign’ and ‘cert’. This is used to generate the keyUsage extension. Please make sure that the algorithm is capable of this usage. Default is to allow encrypt and sign.

Name-DN: subject-name

This is the Distinguished Name (DN) of the subject in RFC-2253 format.

Name-Email: string

This is an email address for the altSubjectName. This parameter is optional but may occur several times to add several email addresses to a certificate.

Name-DNS: string

The is an DNS name for the altSubjectName. This parameter is optional but may occur several times to add several DNS names to a certificate.

Name-URI: string

This is an URI for the altSubjectName. This parameter is optional but may occur several times to add several URIs to a certificate.

Additional parameters used to create a certificate (in contrast to a certificate signing request):

Serial: sn

If this parameter is given an X.509 certificate will be generated. sn is expected to be a hex string representing an unsigned integer of arbitary length. The special value ‘random’ can be used to create a 64 bit random serial number.

Issuer-DN: issuer-name

This is the DN name of the issuer in rfc2253 format. If it is not set it will default to the subject DN and a special GnuPG extension will be included in the certificate to mark it as a standalone certificate.

Creation-Date: iso-date

Not-Before: iso-date

Set the notBefore date of the certificate. Either a date like ‘1986-04-26’ or ‘1986-04-26 12:00’ or a standard ISO timestamp like ‘19860426T042640’ may be used. The time is considered to be UTC. If it is not given the current date is used.

Expire-Date: iso-date

Not-After: iso-date

Set the notAfter date of the certificate. Either a date like ‘2063-04-05’ or ‘2063-04-05 17:00’ or a standard ISO timestamp like ‘20630405T170000’ may be used. The time is considered to be UTC. If it is not given a default value in the not too far future is used.

Signing-Key: keygrip

This gives the keygrip of the key used to sign the certificate. If it is not given a self-signed certificate will be created. For compatibility with future versions, it is suggested to prefix the keygrip with a ‘&’.

Hash-Algo: hash-algo

Use hash-algo for this CSR or certificate. The supported hash algorithms are: ‘sha1’, ‘sha256’, ‘sha384’ and ‘sha512’; they may also be specified with uppercase letters. The default is ‘sha256’.