The message of the quantum

Richard Hughes

Message authenticators for quantum-secured communications facilitate low-latency authentication with assurances of security. Low-latency message authenticators are especially valuable in infrastructure systems where security and latency constraints are difficult to satisfy with conventional non-quantum cryptography. For example, a message transmitter receives a message and derives an authentication tag for the message based at least in part on an authenticator that uses one or more quantum keys. The message transmitter outputs the message and its authentication tag. A message receiver receives a message and authentication tag for the message. The message receiver derives a comparison tag for the message based at least in part on an authenticator that uses one or more quantum keys. The message receiver checks whether the message is authentic based on a comparison of the authentication tag and the comparison tag. In example implementations, the authenticator uses stream-wise cyclic redundancy code operations.

Philippe Blanchard, Jürg Martin Fröhlich

Xiangjun Xin, Xiaolin Hua, Jianpo Song +1 more

Quantum authentication protocols can be used to authenticate both quantum messages and classical messages.In this paper, a new quantum authentication protocol of classical messages is proposed.In our protocol, a sequence of Bell states is shared by the message sender and the corresponding receiver.This sequence is used as the authentication key.Four different unitary operations U 0 , U 1 , U 2 and U 3 are used to encode a classical message m and its hash value h(m) into a sequence of Bell states.To authenticate the classical message, the message receiver extracts m and h(m) from the qubits owned by himself/herself, and verifies whether h(m) matches m.The adversary's disturbance to the quantum channel can be detected by checking whether h(m) matches m.The transmitted message has the properties of both secrecy and authentication.Our quantum authentication protocol is secure against message attack and no-message attack.

William M. Honig

Taewan Kim, Jeong Woon Choi, Nam-Su Jho +1 more

Even though a method to perfectly sign quantum messages has not been known, the arbitrated quantum signature scheme has been considered as one of the good candidates. However, its forgery problem has been an obstacle to the scheme becoming a successful method. In this paper, we consider one situation, which is slightly different from the forgery problem, that we use to check whether at least one quantum message with signature can be forged in a given scheme, although all the messages cannot be forged. If there are only a finite number of forgeable quantum messages in the scheme, then the scheme can be secured against the forgery attack by not sending forgeable quantum messages, and so our situation does not directly imply that we check whether the scheme is secure against the attack. However, if users run a given scheme without any consideration of forgeable quantum messages, then a sender might transmit such forgeable messages to a receiver and in such a case an attacker can forge the messages if the attacker knows them. Thus it is important and necessary to look into forgeable quantum messages. We show here that there always exists such a forgeable quantum message-signature pair for every known scheme with quantum encryption and rotation, and numerically show that there are no forgeable quantum message-signature pairs that exist in an arbitrated quantum signature scheme.