NSA tapping undersea fibers?

David Honig honig at sprynet.com
Mon Jun 4 01:34:02 EDT 2001

At 12:38 AM 6/4/01 -0400, Lenny Foner wrote:
>(Is there technology in existence that can usefully encrypt the entire
>contents of such cables' data stream, end-to-end?  

1. Yes, using counter-modes of operation you can run an
arbitrarily-large array of arbitrarily-slow block cipher 
chips to generate crypto blocks as fast as required.  Each
block cipher chip needs a counter.

e.g., if a chip takes 40 clocks to encrypt, and you need
a new encrypted block to xor with your plaintext on every clock,
you run 40 chips.  The first, started on clock 0, encrypts 0, the second
started on clock 1 encrypts 1, the third 2, etc.  Each clock a 
chip is 'harvested', and that chip's counter increments by 40.

(You don't need decrypt functionality in the block cipher chips to
decrypt, since you are using your bank of staggered, counter-fed
block cipher chips as a keyed pseudorandom stream generator with xor.)

2. Firms which wish to rent out their internal networks
(e.g., during off hours) have an interest in encrypting 
(& tunnelling) all the packets to avoid A. others mapping
their internal networks B. lawsuits when the renters
suspect the rentees of looking at their data C. lawsuits
when the renters are held responsible for the rentee's data.



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