Robustness of an Improved Protocol for QKD with Classical Bob

摘要

Secure key distribution among two remote parties is impossible when both are classical, unless some unproven (and arguably unrealistic) computation-complexity assumptions are made. On the other hand, the above is possible when both parties are quantum. What is possible when only one party (Alice) is quantum, yet the other (Bob) has only classical capabilities? In last year's conference [EQIS'05] we presented a protocols with this constraint. Here we present a simpler such protocol and prove its robustness against attacks: we prove that any attempt of an adversary to obtain information necessarily induces some errors that the legitimate users could notice.