R.S. wrote: >Protected key means CPACF in use, secure key means CryptoExpress card. >The difference can be 1000 times or 10 times. Of course CPACF is always >faster.
>The more cpu-intensive algorithm and the smaller block of data to be >encrypted, the bigger difference is. I think the second sentence is confusing here-not saying it's wrong, just that I can read it a couple of ways, due to English's inherent lack of clarity (not your fault, Radoslaw!). For very large blocks of data, on very CPU-constrained systems that have relatively low CEX use, CEX should be faster relative to CPACF than on less CPU-constrained systems. That is, you look at the CEX interaction as an I/O and CPACF as something that uses some of the "real" CPU as well as being somewhat offloaded, then if "real" CPU is at a premium, and the blocks are large, the cost of the I/O becomes smaller (relatively) than in a less-constrained case, or one with smaller blocks. Consider the cost of a CEX operation as ((ICSF call CPU)+I/O) and the cost of a CPACF operation as ((ICSF call)+(some CPU cycles for the operation)). So the difference is I/O vs. CPACF cycles. The I/O cost doesn't change (much) with larger blocks; the CPACF cycles do. Thus with large blocks, CEX will still be slower than CPACF, just (somewhat) less noticeably so. I had a customer claim CEX could actually be faster in some cases, but they didn't have data to back it up, so I don't believe him (I don't disbelieve him either-more of a Schrödinger's cat deal). -- ...phsiii Phil Smith III p...@voltage.com<mailto:p...@voltage.com> Voltage Security, Inc. www.voltage.com<http://www.voltage.com/> (703) 476-4511 (home office) (703) 568-6662 (cell) ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
