Upcoming Talk(s):
28 June 2024, 2pm-3pm, LIFO meeting room, Bourges (Zoom)
Physical Ring Signature.
Xavier BULTEL
Abstract. (Presentation of an acceptance paper at FUN 2024). Ring signatures allow members of a group (called ring) to sign a message anonymously
within the group, which is chosen ad hoc at the time of signing (the members do not need to have
interacted before). In this paper, we propose a physical version of ring signatures. Our signature is based
on one-out-of-many signatures, a method used in many real cryptographic ring signatures. It consists
of boxes containing coins locked with padlocks that can only be opened by a particular group member.
To sign a message, a group member shakes the boxes of the other members of the group so that the
coins are in a random state (“heads” or “tails”, corresponding to bits 0 and 1), and opens their box to
arrange the coins so that the exclusive “or” of the coins corresponds to the bits of the message they
wish to sign. We present a prototype that can be used with coins, or with dice for messages encoded
in larger (non-binary) alphabets. We suggest that this system can be used to explain ring signatures
to the general public in a fun way.
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