There are Cryptographic policy files present in jre/lib/security. The default policy files are not capable of using stronger encryption algorithms like AES 256.
In order to use them we need to install unrestricted policy files.
The unrestricted policy files provided by Sun works fine but the Sun JRE is not compatible to the IBM JRE from the following scenario.....

If I use the unrestricted policy files from IBM in the Sun JRE 1.6 the following exception occurs.....

Caused by: java.lang.SecurityException: Cannot set up certs for trusted CAs
at javax.crypto.SunJCE_b.<clinit>(DashoA13*..)
... 9 more
Caused by: java.lang.SecurityException: Jurisdiction policy files are not signed
by trusted signers!
at javax.crypto.SunJCE_b.a(DashoA13*..)
at javax.crypto.SunJCE_b.i(DashoA13*..)
at javax.crypto.SunJCE_b.g(DashoA13*..)
at javax.crypto.SunJCE_b$1.run(DashoA13*..)
at java.security.AccessController.doPrivileged(Native

... 10 more

So is Sun Java compatible to IBM java or not?