Editing Prepare and Measure Quantum Digital Signature (section)

==Properties==
*The protocol-
**involves three parties (Seller, Buyer, Verifier) exchanging one-bit classical messages.
**provides information-theoretic security
**provides security against repudiation, i.e. the probability that seller succeeds in making buyer and seller disagree on the validity of her sent quantum signature decays exponentially with L, as stated by the formula <math>P(\text{rep})\le e^{-(s_v-s_a)^2L}</math>.
**provides security against forgery, i.e. any recipient (verifier) with high probability rejects any message which was not originally sent by the seller herself. Forging probability is given by the formula, <math>P(\text{forge})\le e^{-(c_{\min}-2s_v)^2L}</math>, where <math>c_{\min}</math> is 3/8 (calculated using uncertainty principle).