The C5J will also feature RSA encryption, Secure Hashing and support for execution protection to help fight e-mail worms and viruses. The NX feature, according to Via, "marks memory with an attribute that code should not be executed from that memory," assisting the battle against malicious code. NX protection will be supported with Windows XP SP2 – Service Pack 2.Source: The Inquirer
As well as that, the core includes a front side bus of up to 800MHz, a larger L2 cache, and SSE2/SSE3 multimedia instructions.
Via staged demonstrations of their PadLock Hardware Security Suite and other products of theirs at the Embedded Processor Forum 2004, where they also announced the C5J. It will show off this and other stuff at its Technical Forum in Old Taipei, during the Computex trade show.
VIA reveals details of C5J Esther processor

VIA has revealed some details of their 90nm SOI C5J Esther processor core. VIA claims that this processor only uses 3.5W and runs at 1GHz. The C5J is optimized for demanding applications like high compression video streaming and data encryption.