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 ------- Forwarded Message 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. ------- End of Forwarded Message