Messages in this thread | | | Date | Sat, 2 Nov 2002 02:09:45 -0500 | From | Niels Provos <> | Subject | cryptographic acceleration [Re: What's left over.] |
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While discussing various topics related to Linux and the BSDs, this thread was mentioned.
>The question I have is whether such external hardware is even worth it >any more for any standard crypto work. With a regular PCI bus >fundamentally limiting throughput to something like a maximum of 66MB/s >(copy-in and copy-out, and that's so theoretical that it's not even The following paper
Performance Analysis of TLS Web Servers. C. Coarfa, P. Druschel, and D. Wallach. In Proceedings of NDSS '02, 2002. http://www.isoc.org/isoc/conferences/ndss/01/2001/papers/dean02.pdf
analyzes the performance benefits from off-loading various crypto operations to cryptographic hardware accelerators in comparison to software crypto. This is in the context of web servers and TLS.
The paper concludes that hardware accelerators are useful for speeding up public key cryptography, whereas symmetric encryption (RC4) does not benefit from hardware acceleration very much.
For public-key cryptography, the used bus bandwidth is not significant because data transfers are usually small.
On the other hand, there are some Ethernet cards that support inline encryption so that not additional bus bandwidth is required to do both public and symmetric key cryptography.
Things are slightly different for expensive symmetric encryption algorithms like 3DES. See
A Study of the Relative Costs of Network Security Protocols Stefan Miltchev, Sotiris Ioannidis, and Angelos D. Keromytis http://www.cs.columbia.edu/~angelos/Papers/ipsecspeed.pdf
>Chris is write that crypto api is misdesigned if we want to use hardware >cryptocards Angelos Keromytis has designed an API for cryptographic services in the kernel. The implementation provides a good abstraction.
Anyway, now you have some numbers.
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