1993-02-21 - Trapdoors

Header Data

From: Eric Hughes <hughes@soda.berkeley.edu>
To: cypherpunks@toad.com
Message Hash: 6b2ec4a49ee65fe1631aa1d6563107947df0552b0949c449557264dbae00fbb0
Message ID: <9302212154.AA02012@soda.berkeley.edu>
Reply To: <9302182057.AA00885@tadpole.tadpole.com>
UTC Datetime: 1993-02-21 21:58:03 UTC
Raw Date: Sun, 21 Feb 93 13:58:03 PST

Raw message

From: Eric Hughes <hughes@soda.berkeley.edu>
Date: Sun, 21 Feb 93 13:58:03 PST
To: cypherpunks@toad.com
Subject: Trapdoors
In-Reply-To: <9302182057.AA00885@tadpole.tadpole.com>
Message-ID: <9302212154.AA02012@soda.berkeley.edu>
MIME-Version: 1.0
Content-Type: text/plain


Jim writes:
>Interestingly enough, V9 SPARC has a population count (number of bits
>set in word) instruction that was put in specificly at the request of
>No Such Agency.

Does anybody have a good idea what applications this is useful for?

My first thought is that it's a very quick way to do linear error
detection codes, since this instruction directly computes the Hamming
weight of a code word.

I can also see it being useful to detect correlations between
sequences, such as a trial random stream and a known pseudorandom
number generator.  One would XOR the streams together and then count
bits to calculate a correlation frequency.

Other ideas?

Eric

Thread

• Return to February 1993

• Return to “cp@jido.b30.ingr.com (Craig Presson)”
• Return to “Eric Hughes <hughes@soda.berkeley.edu>”
• Return to “henry strickland <strick@osc.versant.com>”
• Return to “jim@tadpole.com (Jim Thompson)”
• Return to “peter honeyman <honey@citi.umich.edu>”

• Return to “Phiber Optik <phiber@eff.org>”

• 1993-02-18 (Thu, 18 Feb 93 12:58:33 PST) - Re: Trapdoors - jim@tadpole.com (Jim Thompson)
  • 1993-02-21 (Sun, 21 Feb 93 13:58:03 PST) - Trapdoors - Eric Hughes <hughes@soda.berkeley.edu>
    • 1993-02-21 (Sun, 21 Feb 93 14:28:36 PST) - Re: Trapdoors - henry strickland <strick@osc.versant.com>
      • 1993-02-22 (Mon, 22 Feb 93 12:58:17 PST) - Re: Trapdoors - cp@jido.b30.ingr.com (Craig Presson)
        • 1993-02-23 (Mon, 22 Feb 93 19:38:12 PST) - Re: Trapdoors - peter honeyman <honey@citi.umich.edu>
          • 1993-02-23 (Mon, 22 Feb 93 21:00:43 PST) - Re: Trapdoors - Phiber Optik <phiber@eff.org>