Exporting a Certificate Authenticating Your Public Key
Suppose you have used the jarsigner tool to sign a Java™ ARchive (JAR) file. Clients that want to use the file will want to authenticate your signature.
One way they can do this is by first importing your public key
certificate into their keystore as a "trusted" entry. You can export
the certificate and supply it to your clients. As an example, you
can copy your certificate to a file named MJ.cer by using the following
command, assuming the entry is aliased by "mykey":
keytool -exportcert -alias mykey -file MJ.cer