I am using jsch 0.1.42 together with Ant 1.7.1, and also jsch01.49 with the non released Ant 1.9.0-alpha.
Wiith both combos and Java 1.7 I am getting verify: false errors thrown likely by the Session class of jsch.
The exception is not thrown systematically, I think it happens currently 30% fo the time.
We are connecting to openssh servers on linux and to cygwin ssh on windows.
We are building concurrent connections inside an ant build file using parallel and sshexec. This works well with Java 1.6.
I am not 100% sure as of now what is causing the bug and how to fix it.