[cap-talk] FW: x.509 -- MD5 considered harmful today

[zooko]

On Dec 31, 2008, at 15:20 PM, Bill Frantz wrote:

> In my experience, the code which performs the I/O is frequently  
> expensive enough to be a bottle neck. Many compression functions  
> can pay for themselves by reducing the CPU cost of the I/O. How do  
> these hash functions compare in CPU cost with common compression  
> functions?


Secure hash functions are more expensive.  SHA-256 is about 21 cycles  
per byte.  The fastest open source compression (multi-algorithm, type- 
detecting) that I know of -- FreeARC -- is about 3.7 cycles per  
second (on a standard test set).  zlib is about 16 cycles per byte.

I'm hoping that SHA-3 will turn out to be substantially faster than  
SHA-256, but it might not be.

Regards,

Zooko
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