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Re: CBC makes Implementations too Slow.





ji@research.att.com wrote:

> Maybe I'm missing something, but packets are sent in a bit-serial manner
> in almost all cases; you can be encrypting block n+1 while you are
> transmitting the (already encrypted) block n.  Since you have to transmit
> some headers in the clear, you can start encryption of the payload at the
> same time as the cleartext headers are being transmitted; so long as 
> you can encrypt at line speeds, you keep the pipelines full.  Isn't that
> what we want?


Except that the hash of the data is placed in a field of the header :-)

Encryption at 'line rate' necessarily implies at least a 1-packet 
latency on the sender's end.

(note - this happens even for TCP, which requires two passes of delay - 
one to calculate the checksum and place it in the TCP header, one to 
calculate the hash)

Joe




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