Cryptography – Particular algorithmic function encoding – Nbs/des algorithm
Patent
1996-03-08
1998-05-26
Barron, Jr., Gilberto
Cryptography
Particular algorithmic function encoding
Nbs/des algorithm
359112, 359181, H04L 908
Patent
active
057579121
DESCRIPTION:
BRIEF SUMMARY
RELATED APPLICATIONS
This application is related to the following co-pending commonly assigned applications:
U.S. application Ser. No. 08/612,881, filed Apr. 22, 1996 entitled "METHOD FOR KEY DISTRIBUTION USING QUANTUM CRYPTOGRAPHY" naming Messrs. Phoenix and Barnett as inventors;
U.S. application Ser. No. 08/612,880, filed Mar. 8, 1996, entitled "SYSTEM AND METHOD FOR KEY DISTRIBUTION USING QUANTUM CRYPTOGRAPHY" naming Messrs. Townsend and Blow as inventors;
U.S. application Ser. No. 08/605,048, filed Mar. 7, 1996 entitled "KEY DISTRIBUTION IN A MULTIPLE ACCESS NETWORK USING QUANTUM CYPTOGRAPHY" naming Messrs. Townsend and Smith as inventors; and
U.S. application Ser. No. 08/776,296, filed Jan. 30, 1997, entitled "QUANTUM CRYPTOGRAPHY" naming Mr. Townsend as the inventor.
This application is also related to U.S. Pat. No. 5,675,648, filed Aug. 15, 1995, issued Oct. 7, 1997, entitled "SYSTEM AND METHOD FOR KEY DISTRIBUTION USING QUANTUM CRYPTOGRAPHY" naming Mr. Townsend as the inventor.
BACKGROUND TO THE INVENTION
1. Field of the Invention
The present invention relates to a system for the communication of encrypted data and in particular to a system employing the technique known as quantum cryptography.
2. Related Art
In quantum cryptography data is encoded at the transmitter and decoded at the receiver using some specified algorithm which is assumed to be freely available to all users of the system, whether authorised or otherwise. The security of the system depends upon the key to the algorithm being available only to the authorised users. To this end, the key is distributed over a secure quantum channel, that is a channel carried by single-photon signals and exhibiting non-classical behaviour, as further discussed below. In the present specification, the term "single-photon" encompasses any signal having the required quantum properties. It may be generated from a highly attenuated source having in general no more than one and on average very much less than one photon per output signal, or may comprise single-photons generated by parametric down conversion. Both these techniques are described and claimed in our copending International application PCT/GB 93/02637 (WO 94/15422), the disclosures of which are incorporated herein by reference.
After the exchange of single-photon signals, the transmitter and the receiver then communicate over a separate channel, known as the public channel, to compare the transmitted and the received data. The presence of any eavesdropper intercepting the transmitted key results in a change in the statistics of the received data, which can be detected. Accordingly, in the absence of any such change in the statistics of the data, the key is known to be secure. The secret key thus established is used in the encryption and decryption of subsequent communications between the transmitter and receiver. The subsequent transmissions will generally, but not necessarily, be carried on the same transmission channel as was used for establishing the key. For added security, the existing key may periodically be replaced by a newly generated key.
In general, a method of communication using quantum cryptography includes the steps of:
(a) randomly selecting one of a plurality of coding alphabets corresponding to different non-commuting quantum mechanical operators and encoding a signal for transmission on the quantum channel using the selected operator;
(b) randomly selecting one of the different quantum mechanical operators and using that in detecting the signal transmitted in step (a);
(c) repeating steps (a) and (b) for each of a multiplicity of subsequent signals;
(d) communicating between the transmitter and the receiver independently of the encryption alphabets to determine for which of the transmitted signals common operators were selected by the transmitter and receiver;
(e) comparing the signals transmitted and received in steps (a) and (b) to detect any discrepancy resulting from the presence of an eavesdropper; and,
(f) in the event that in step (e) no eavesdropper is detected, u
REFERENCES:
patent: 4965856 (1990-10-01), Swanic
patent: 5191614 (1993-03-01), LeCong
patent: 5243649 (1993-09-01), Franson
patent: 5307410 (1994-04-01), Bennett
patent: 5311592 (1994-05-01), Udd
patent: 5339182 (1994-08-01), Kimble et al.
patent: 5418905 (1995-05-01), Rarity et al.
patent: 5515438 (1996-05-01), Bennett et al.
patent: 5675648 (1997-10-01), Townsend
C. H. Bennett; Physical Rev. Let.; vol. 68, No. 21, 25 May 1992, pp. 3121-3124.
IBM Technical Disclosure Bulletin; vol. 26, No. 8, Jan., 1984, pp. 4363-4366.
IBM Technical Disclosure Bulletin; vol. 28, No. 7, Dec., 1985, pp. 3153-3163.
Barron Jr. Gilberto
British Telecommunications public limited company
LandOfFree
System and method for quantum cryptography does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for quantum cryptography, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for quantum cryptography will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1973245