Editing Quantum Digital Signature (section)

==Properties==
All QDS protocols are divided into two phases, distribution and messaging. Distribution phase enables sender to generate private keys (kept secret with sender) and public keys (information distributed to recipients) while messaging phase enables exchange of messages using the above keys. For simplicity, most protocols use the case of three parties, one sender (Seller) and two recipients (Buyer and Verifier) exchanging one-bit classical messages signed by Quantum Digital Signatures (QDS).  

*A QDS scheme is correct if a message signed by a genuine sender is accepted by a recipient with unit probability.
*A QDS scheme is secure if no one but the sender can sign a message such that it is accepted by a recipient with non-negligible probability. 
*'''Transferability''' means that at any point a recipient (buyer) can prove it to another recipient (verifier) that the concerned message has been signed by the claimed sender (Seller).
*'''Unforgeability''' ensures that a dishonest recipient (buyer) can neither alter a DS nor sign a message with a fake DS (DS that has not come from a genuine sender) and forward it to other recipients (verifier) successfully. 
*'''Non-Repudiation''' implies that at any point a dishonest sender (seller) cannot deny having signed the message sent to a genuine recipient (Buyer).