AES256 cipher does not work

Lee Painter

When attempting to configure the aes256-cbc or aes256-ctr ciphers an exception is seen when attempting to connect to a server.

Exception: com.maverick.ssh.SshException: java.io.IOException
java.io.IOException: Invalid encryption key

The JCE is probably restricting access to the 256 bit cipher due to the jurisdiction policy files, without the unlimited strength jurisdiction policy files installed in the JRE the maximum limit of a cipher is 128 bits.

Here is a useful article that shows how to test if the cipher bit length is restricted.

http://stackoverflow.com/questions/11538746/check-for-jce-unlimited-strength-jurisdiction-policy-files

Download the 'Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files' from http://java.sun.com/javase/downloads/index.jsp and follow the instructions