Sun Microsystems' product plans are up in the air pending its acquisition by Oracle, but the company's chip engineers continue to present new designs in the hope they'll see the light of day.

At the Hot Chips conference at Stanford University on Tuesday, Sun presented plans for a security accelerator chip that it said would reduce encryption costs for applications such as VoIP calls and online banking Web sites.

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The chip, known as a coprocessor, will be included on the same silicon as Rainbow Falls, the code name for the follow-on to Sun's multithreaded Ultrasparc T2 processor.

Most coprocessors are separate from the CPU. They offload tasks that use a lot of computing power, such as cryptographic processing, so that the main processor is free to do other work.

But having the security coprocessor as a separate chip makes it unsuitable for some types of applications, according to Sun engineer Lawrence Spracklen.

For applications that require data to be encrypted in small packets, such as VoIP calls and programs that use IPsec, it's impractical to offload the work to an external chip because there is too much latency moving the data back and forth to the CPU, he said.

Moving the coprocessor onto the same silicon as Rainbow Falls will virtually eliminate the latency and will make it practical for companies to use cryptography more widely, he said.

Besides VoIP and IPsec programs, online banking sites also require small packets of data to be encrypted, because of all the fields and graphical elements that tend to appear on the page. Traffic to and from those sites is encrypted today, but at a substantial cost to CPU performance, he said.

Sun is giving a presentation about Rainbow Falls later on Tuesday, but it's not expected to provide a shipping date. Oracle has said it plans to continue development of Sun's Sparc chips, but it has given no details and plans for individual products are unknown. That means it's unclear if Rainbow Falls and its on-chip security accelerator will see the light of day.