DocumentCode :
3217547
Title :
Authentication of quantum messages
Author :
Barnum, Howard ; Crépeau, Claude ; Gottesman, Daniel ; Smith, Adam ; Tapp, Alain
Author_Institution :
Los Alamos Nat. Lab., NM, USA
fYear :
2002
fDate :
2002
Firstpage :
449
Lastpage :
458
Abstract :
Authentication is a well-studied area of classical cryptography: a sender A and a receiver B sharing a classical secret key want to exchange a classical message with the guarantee that the message has not been modified or replaced by a dishonest party with control of the communication line. In this paper we study the authentication of messages composed of quantum states. We give a formal definition of authentication in the quantum setting. Assuming A and B have access to an insecure quantum channel and share a secret, classical random key, we provide a non-interactive scheme that enables A to both encrypt and authenticate an m qubit message by encoding it into m+s qubits, where the error probability decreases exponentially in the security parameter s. The scheme requires a secret key of size 2m+O(s). To achieve this, we give a highly efficient protocol for testing the purity of shared EPR pairs. It has long been known that learning information about a general quantum state will necessarily disturb it. We refine this result to show that such a disturbance can be done with few side effects, allowing it to circumvent cryptographic protections. Consequently, any scheme to authenticate quantum messages must also encrypt them. In contrast, no such constraint exists classically. This reasoning has two important consequences: It allows us to give a lower bound of 2m key bits for authenticating m qubits, which makes our protocol asymptotically optimal. Moreover, we use it to show that digitally signing quantum states is impossible.
Keywords :
computational complexity; message authentication; protocols; quantum cryptography; authentication; cryptography; digital signature; disturbance; encoding; error probability; insecure quantum channel; noninteractive scheme; protocol; quantum messages; quantum states; qubits; receiver; secret classical random key sharing; security parameter; sender; Authentication; Communication system control; Computer science; Cryptographic protocols; Cryptography; Information security; Paramagnetic resonance; Purification; Teleportation; Testing;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Foundations of Computer Science, 2002. Proceedings. The 43rd Annual IEEE Symposium on
ISSN :
0272-5428
Print_ISBN :
0-7695-1822-2
Type :
conf
DOI :
10.1109/SFCS.2002.1181969
Filename :
1181969
Link To Document :
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