[6759] in cryptography@c2.net mail archive
Re: Looking for a cryptographic primitive
daemon@ATHENA.MIT.EDU (Greg Rose)
Thu Mar 9 14:59:19 2000
Message-Id: <4.2.0.58.20000310062603.00afd360@127.0.0.1>
Date: Fri, 10 Mar 2000 06:27:56 +1100
To: bram <bram@gawth.com>
From: Greg Rose <ggr@qualcomm.com>
Cc: cryptography@c2.net
In-Reply-To: <Pine.LNX.4.10.10003090547340.20126-100000@ultra.gawth.com>
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At 05:50 9/03/2000 -0800, bram wrote:
>Does anybody know of a field in which a + b and a * b can be computed
>quickly but (and this is important) it's computationally intractable to
>compute the additive inverse of a?
If you literally mean "field", there must be a multiplicative identity,
called "1". If you calculate its additive inverse, which is surely
tractable as a one-time computation, then additive inverses generally can
be computed as x*-1, which you postulate to be easy.
Greg.
Greg Rose INTERNET: ggr@Qualcomm.com
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