Signing Code and Granting It Permissions

Generate Keys

If a code signer does not yet have a suitable private key for signing the code, the key must first be generated, along with a corresponding public key that can be used by the code receiver's runtime system to verify the signature.

Since this lesson assumes that you don't yet have such keys, you are going to create a keystore named susanstore and create an entry with a newly generated public/private key pair (with the public key in a certificate).

Now pretend that you are Susan Jones and that you work in company ABC's purchasing department. Type the following command in your command window to create a keystore named susanstore and to generate keys for Susan Jones:

keytool -genkey -alias signFiles -keypass kpi135 
 -keystore susanstore -storepass ab987c

(Note: This must be typed as a single line.)

Subparts of the keytool Command

Let's look at what each of the keytool subparts mean.

• The command for generating keys is -genkey.
• The -alias signFiles subpart indicates the alias to be used in the future to refer to the keystore entry containing the keys that will be generated.
• The -keypass kpi135 subpart specifies a password for the private key about to be generated. This password will always need to be used in order to access the keystore entry containing that key. The entry doesn't have to have its own password; if you don't include a -keypass option, you will be prompted for the key password and given the option of letting it be the same as the keystore password.
• The -keystore susanstore subpart indicates the name (and optionally path) of the keystore you are creating or already using.
• The -storepass ab987c subpart indicates the keystore password. If you don't include a -storepass option, you will be prompted for the keystore password.

For security reasons you actually should not supply your key or keystore passwords on the command line, because they can be intercepted more easily that way. Instead you should leave off the -keypass and the -storepass options and type your passwords when you are prompted for them.

Distinguished-Name Information

If you use the preceding command, you will be prompted for your distinguished-name information. Following are the prompts; the bold indicates what you should type.

What is your first and last name?
  [Unknown]:  Susan Jones 
What is the name of your organizational unit?
  [Unknown]:  Purchasing 
What is the name of your organization?
  [Unknown]:  ABC 
What is the name of your City or Locality?
  [Unknown]:  Cupertino 
What is the name of your State or Province?
  [Unknown]:  CA 
What is the two-letter country code for this unit?
  [Unknown]:  US 
Is <CN=Susan Jones, OU=Purchasing, O=ABC, L=Cupertino, ST=CA, C=US> correct?
  [no]:  y 

Command Results

The keytool command creates the keystore named susanstore (if it doesn't already exist) in the same directory in which the command is executed and assigns it the password ab987c. The command generates a public/private key pair for the entity whose distinguished name has a common name of Susan Jones and the organizational unit of Purchasing.

The command creates a self-signed certificate that includes the public key and the distinguished-name information. (The distinguised name you supply will be used as the "subject" field in the certificate.) This certificate will be valid for 90 days, the default validity period if you don't specify a -validity option. The certificate is associated with the private key in a keystore entry referred to by the alias signFiles. The private key is assigned the password kpi135.

Note: The command could be shorter if option defaults are accepted or you wish to be prompted for various values. Whenever you execute a keytool command, defaults are used for unspecified options that have default values, and you are prompted for any required values. For the genkey command, options with default values include alias (whose default is mykey), validity (90 days), and keystore (the file named .keystore in your home directory). Required values include dname, storepass, and keypass.

Signing Code and Granting It Permissions