It's likely all certificate information is in the jar:
"
The Signature Block (.DSA) File
The .SF file is signed and the signature is placed in the .DSA file. The
.DSA file also contains, encoded inside it, the certificate or certificate
chain from the keystore which authenticates the public key corresponding to
the private key used for signing.
"
http://java.sun.com/j2se/1.5.0/docs/tooldocs/solaris/jarsigner.htmljarsigner -verify -verbose -certs my.jar will display some details but not
all.
Maybe it requires a bit of programming to get the information you want ?