Gottesman and Chuang Quantum Digital Signature: Difference between revisions

Gottesman and Chuang signature scheme is based on quantum [https://en.wikipedia.org/wiki/One-way_function one way functions], which take classical bit string as input and give quantum states as output. Quantum Digital Signature (QDS) protocols can be divided into two stages: the distribution stage, where quantum signals (public keys) are sent to all recipients, and the messaging stage, where classical messages are signed, sent and verified. Here, we take the case of three parties, one sender (referred to as seller) and two receivers (buyer and verifier) sharing a one bit message.  

*'''Distribution:''' For each message bit (say 0 and 1) sender selects a classical bit string. This is chosen to be her private key. Using the quantum one way function, Sender generates the output of the quantum one-way function/map, which (the output) she calls her public key and as assumed, distributes them to each recipient, for each message bit. In the end of this step, each recipient has two public keys, one for message bit 0 and one for message bit 1.

*'''Messaging:''' Sender sends her message bit with the associated private key. The Receiver performs the map on the private key (quantum one way function takes the sent private key as input) and the compares the output thus generated with the public key received in the previous stage. If the number of unmatched bits are below rejection threshold, the message is declared valid, else invalid. If the number of unmatched bits is below acceptance threshold, it is declared transferable, else not transferable.