From: composer@Beyond.Dreams.ORG (Jeff Kellem)
Date: Tue, 4 May 93 13:10:22 PDT
To: cypherpunks@toad.com
Subject: TALK: Boston Univ CS Dept Colloquium--Digital Signatures, 6 May, 11am
Message-ID: <9305042010.AA28513@Beyond.Dreams.ORG>
MIME-Version: 1.0
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For those in the Boston area this Thursday, 6 May 93, this talk may be of
interest.  FYI...

			-jeff

Jeff Kellem
Internet: composer@Beyond.Dreams.ORG

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			     BOSTON UNIVERSITY

			 CS DEPARTMENT COLLOQUIUM


			 Thursday, May 6 at 11:00

		   Math and Computer Science Bldg (MCS)
		      Room 135, 111 Cummington Street
			     Boston, MA  02215



ON-LINE/OFF-LINE DIGITAL SIGNATURES


Shimon Even

Computer Science Department
Technion - Israel Institute of Technology


Joint work with Oded Goldreich and Silvio Micali

ABSTRACT

A signature scheme is proposed. It consists of two phases. The
first phase is performed off-line, before the message to be signed
is even known. The second on-line phase is performed once the message
to be signed is known. The scheme has a practical advantage as well as a
theoretical value.

It is shown that the on-line phase can be carried out very quickly,
by using a one-time signature scheme. The off-line phase can use a
simplified version of the square extraction method of Rabin. It
requires a moderate amount of computation, but can be performed
leisurely, before the message to be signed is even known. Thus, the
scheme may be of practical value in scenarios such as that of
electronic fund transfer.

It is proved that if the building blocks are secure against known
message attack, the scheme is secure against chosen message attack.


There will be tea at 10:45.

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