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==Properties== | ==Properties== | ||
Security of | Security of an anonymous transmission protocol is defined in terms of the guessing probability, i.e., the maximum probability that adversaries guess the identity of the sender <math>S</math> or receiver <math>R</math> given all the classical and quantum information they have available at the end of the protocol. | ||
*'''Guessing probability''' Let <math>\mathcal{A}</math> be a subset of adversaries among <math>n</math> nodes. Let <math>C</math> be the register that contains all classical and quantum side information accessible to the adversaries. Then, the probability of adversaries guessing the sender is given by | *'''Guessing probability''' Let <math>\mathcal{A}</math> be a subset of adversaries among <math>n</math> nodes. Let <math>C</math> be the register that contains all classical and quantum side information accessible to the adversaries. Then, the probability of adversaries guessing the sender is given by | ||
<math> P_{\text{guess}}[S|C, S\notin \mathcal{A}] = \max_{\{M^i\}} \sum_{i \in [n]} P[S=i|S\notin \mathcal{A}] \text{Tr}[M^i \cdot \rho_{C|S=i} ],</math></br> | <math> P_{\text{guess}}[S|C, S\notin \mathcal{A}] = \max_{\{M^i\}} \sum_{i \in [n]} P[S=i|S\notin \mathcal{A}] \text{Tr}[M^i \cdot \rho_{C|S=i} ],</math></br> |