EP1374475A2 - Dispositif et procede destines a etre utilises en cryptographie quantique - Google Patents

Dispositif et procede destines a etre utilises en cryptographie quantique

Info

Publication number
EP1374475A2
EP1374475A2 EP02759800A EP02759800A EP1374475A2 EP 1374475 A2 EP1374475 A2 EP 1374475A2 EP 02759800 A EP02759800 A EP 02759800A EP 02759800 A EP02759800 A EP 02759800A EP 1374475 A2 EP1374475 A2 EP 1374475A2
Authority
EP
European Patent Office
Prior art keywords
quantum
light signals
optics
light
quantum cryptography
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02759800A
Other languages
German (de)
English (en)
Inventor
Harald Weinfurter
Christian Kurtsiefer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
qutools GmbH
Original Assignee
Ludwig Maximilians Universitaet Muenchen LMU
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ludwig Maximilians Universitaet Muenchen LMU filed Critical Ludwig Maximilians Universitaet Muenchen LMU
Publication of EP1374475A2 publication Critical patent/EP1374475A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0852—Quantum cryptography

Definitions

  • Quantum cryptography enables quantifiable, secure communication. By transmitting quantum particles, especially photons, a random, secure key can be generated. This key can also be used for encryption according to known methods (e.g. one-time pad, DES). Any eavesdropping attempts change the quantum particles in such a way that errors in the generated key make the attack recognizable. This is in marked contrast to conventional methods, in which the security of the transmission is based, for example, on trust in couriers or on (unproven) assumptions about the technological capabilities of the listener.
  • Quantum cryptography was first theoretically proposed in 1984 and experimentally implemented in 1991. A number of theoretical and experimental publications and patents led to the rapid development of the area. Today, research on quantum cryptography focuses primarily on the technical implementation of the first prototype. Great attention is paid to the miniaturization of the systems used and to the great stability and economy of the transmitter and receiver optics.
  • the present invention relates to a system for the secure distribution of cryptographic keys according to the method of quantum cryptography.
  • quantum cryptography as is known from US5307410 [1] and US5732139 [2], a cryptographic key is used between two or more participants by transmitting information-carrying light signals via the quantum channel, by measuring these signals and by exchanging information about the measurements via a classic communication channel generated. Possible eavesdropping attacks during the transmission of the light signals can be proven based on knowledge of quantum theory.
  • the generated cryptographic key is of great importance for the transmission of messages of all kinds because of its high security.
  • [8-11] discloses devices which do not require any switches due to the use of 2 or more signal sources or 2 or more analysis channels.
  • the light signals emitted by the signal sources are superimposed in the transmitting device by means of optical components, in particular semi-transparent mirrors, or the light signals are divided in the receiving device using a semi-transparent mirror.
  • the signal sources are checked in such a way that at one point in time only one of the sources generates a single photon or an attenuated light pulse at the output of the transmission unit.
  • the incoming photon is randomly distributed to the different analyzers by a beam splitter and registered by one of the detectors, which results in the signal relevant for key generation.
  • the object of the invention is to provide an improved device and an improved method for quantum cryptography.
  • the signal sources are spatially arranged in such a way that wave fronts of the light signals they emit partially overlap at the input of the quantum channel, and / or the analysis channels are spatially arranged such that the wavefront of the light signals coming from the quantum channel is spatially divided and at least 2 of the parts in a quantum mechanical state.
  • mirrors or other components that change the wavefront are used.
  • the size of the transmitting or receiving optics can be significantly reduced without disturbing the quantum mechanical states of the light signals.
  • Mirrors, prisms, glass plates, lenses and / or diffractive elements can be used as components that change the wavefront.
  • the distribution ratio can be adjusted to the different analysis channels and optimized for the specific application.
  • the randomness of the distribution over several analysis channels is guaranteed by the spatial division of the light cone. According to quantum mechanics, the detection of a single photon light signal is random and indefinite in the different parts of a light cone.
  • the spatial superimposition or division of the light cones can be used flexibly for several types of quantum mechanical states.
  • the quantum mechanical state in an embodiment according to the invention can be realized by the property of the polarization of the light signals, or alternatively by a phase difference of temporally offset components of the light signal, or by a phase difference of frequency components of the light signal.
  • An advantageous variant of the invention carries out analysis channels in such a way that optical components are used together for several channels without losing full functionality. This reduces the complexity, the price and also the size of the receiving optics.
  • the present invention is formed by the geometric overlap of the light beams generated by the signal sources at the output and by the geometric division of the light beams at the receiver.
  • the randomness required for quantum cryptography at the receiver is not guaranteed by the randomness of the detection in the outputs of a beam splitter, but by the randomness of the detection in geometrically different parts of the light beam.
  • the present invention has a cryptographic transmitter with at least 2 signal sources, in which at least 2 of the available signal sources are set non-orthogonally in the sense of a quantum mechanical preparation, and which is characterized in that the light coming from the signal sources spatially overlaps at the output of the transmitter and in exits the quantum channel.
  • the spatial overlap can be achieved either solely by the beam divergence of the signal sources or with the aid of mirrors, lenses, prisms or refractive elements.
  • the present invention also has a cryptographic receiving unit with at least two measuring devices with quantum mechanical properties, at least 2 of the measuring devices being oriented non-orthogonally in the sense of a quantum mechanical measurement, and which is characterized in that the light beam coming from the quantum channel is geometrically divided between the measuring devices.
  • the distribution ratio between the various measuring devices can be changed by changing the position of the measuring devices or the components introduced (mirror, lens, prism, glass plate, refractive element).
  • quantum mechanics it is indefinite and random in which part of the light beam, i.e. in which one of the measuring devices a single photon coming from the quantum channel is detected.
  • a quantum cryptography system can use either one of the above-mentioned transmitters or one of the above-mentioned receivers, or both.
  • the transmitter can also be equipped with additional signal sources, which are designed such that they emit light in the output, which for adjustment, synchronization or message transmission within the
  • Quantum cryptography system can be used.
  • the signal sources are light sources, characterized in that the light emitted by them and coupled out into the quantum channel is either (a) a well-defined one Has polarization orientation, or (b) has a certain relative phase position at different times, or (c) has a relative phase position for different frequencies. This is achieved by means of polarizers and / or phase elements which are introduced into the light beam.
  • Measuring devices register light, whereby (a) the polarization of the light has a certain orientation, (b) the light coming at different times has a certain relative phase position, (c) the light coming with different frequencies has a certain relative phase position.
  • the receiver can be equipped with further measuring devices for the purpose of synchronization, adjustment, security checks and message transmission within the quantum cryptography system.
  • FIG. 2a shows a variant of FIG. 2 with a shortened overall length
  • Fig. 3 shows a preferred embodiment of a recipient
  • Fig. 4 shows a further preferred embodiment of a receiver.
  • an external source determines a number which emits a short light pulse from several signal sources (11-14).
  • the signal sources used in the present embodiment are laser diodes which emit light of a well-defined linear polarization (degree of polarization> 97%).
  • the laser diodes are oriented in such a way that the polarization of the light they emit is rotated in each case by 45 ° to the preceding laser diode.
  • a light pulse with a polarization direction of 0 ° (vertical polarization direction Xll), 45 ° (12), 90 ° (horizontal) (13), or 135 ° (14) is emitted.
  • the laser diodes are arranged in a semicircle in such a way that similar portions of the emitted light overlap due to the beam divergence at the output (see indicated light cone in front view).
  • a concave lens (convex mirror) can be inserted into the beam path to reduce the overall length or to adjust the beam divergence.
  • the light is coupled into a single-mode glass fiber (15) (quantum channel) at the output.
  • FIG. 2 couples the light emitted by differently oriented laser diodes (21-24) (possibly via a lens or via a mirror) into one Cover (25), which is used for room filtering.
  • the light emerging here can be processed as a quantum channel via additional lenses (26) (and possibly diaphragms, telescope arrangement) for an optical microwave link.
  • additional laser diodes can be attached to the center of the 4 laser diodes, whose emitted light can be used for synchronization and adjustment.
  • a conical mirror element (27) can be used to shorten the overall length (FIG. 2a). This is arranged in the center of an annular arrangement of the laser diodes (28) in such a way that the divergence of the light beams can advantageously be adapted to the divergence of the spatial filter (29) and the quantum channel (30).
  • light comes from the single-mode glass fiber (quantum channel) (31) from the transmitter and is collimated by a lens (32) or focused on the detectors.
  • a mirror (33) is partially introduced into the light beam thus expanded, which thereby reflects a corresponding part of the light to an analysis unit.
  • the other part of the light beam passes through a wave plate (34) and then strikes another analysis unit.
  • the wave plate is oriented in such a way that linearly polarized light is transformed into vertically (horizontally) polarized light at 45 ° (-45 °).
  • Both analysis units consist of a polarizing beam splitter (35, 36) and 2 single photon detectors (37- 40).
  • the polarizing beam splitter reflects vertically polarized light and transmits horizontally polarized light.
  • the signal from the single-photon detectors characterizes the detected polarization: 0 ° (37), 45 ° (39), 90 ° (38), 135 ° (40).
  • Appropriate electronics for signal processing make it correspondingly better known
  • the light comes through a spatial filter with lenses (41) orifices (42).
  • the light emerging through the last aperture is focused on the detectors by a lens (43).
  • a plane-parallel glass plate (44) is placed in the right part of the light beam. It is tilted in such a way that the continuous light is shifted horizontally to the right.
  • a wave plate (45) is introduced into the left partial beam. It is oriented in such a way that linearly polarized light is transformed into vertically (horizontally) polarized light at 45 ° (-45 °).
  • Both partial beams enter a polarizing beam splitter (46) which transmits horizontally polarized light and reflects vertically polarized light.
  • both measuring channels use the same polarizing beam splitter.
  • the transmitted or reflected light is registered by 4 single photon detectors (47-50). These detectors are arranged in pairs in the transmitted beam and in the reflected beam behind a mirror (51) such that the left detector detects light that previously passed through the wave plate and the right detector detects light that previously passed through the plane-parallel plate.
  • the signal from the single-photon detectors also identifies the detected polarization and is processed by suitable electronics for signal processing in accordance with known quantum cryptography protocols.
  • the novelty of this invention is to be seen in the use of wavefront overlay (at the transmitter) or in the use of wavefront division (at the receiver).
  • Quantum cryptography is the only key distribution method that ensures quantifiable security. This security is not provided when using conventional software methods, and although additional devices are required, there is also a clear advantage over key delivery by couriers.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)
  • Spectrometry And Color Measurement (AREA)

Abstract

La présente invention concerne un système de cryptographie quantique permettant de générer de manière sûre des clés, en particulier au moyen de sources de signaux et de canaux d'analyse. Ces sources de signaux sont séparées spatialement de telle sorte que les fronts d'ondes des signaux lumineux émis par ces sources se chevauchent partiellement à l'entrée du canal quantique. Les canaux d'analyse sont disposés de telle sorte que le front d'ondes des signaux lumineux provenant du canal quantique soit divisé spatialement et qu'au moins deux des parties soient analysées dans un état mécanique quantique.
EP02759800A 2001-04-06 2002-04-05 Dispositif et procede destines a etre utilises en cryptographie quantique Withdrawn EP1374475A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10117272A DE10117272B4 (de) 2001-04-06 2001-04-06 Vorrichtung und Verfahren für die Quantenkryptographie
DE10117272 2001-04-06
PCT/EP2002/003825 WO2002082714A2 (fr) 2001-04-06 2002-04-05 Dispositif et procede destines a etre utilises en cryptographie quantique

Publications (1)

Publication Number Publication Date
EP1374475A2 true EP1374475A2 (fr) 2004-01-02

Family

ID=7680689

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02759800A Withdrawn EP1374475A2 (fr) 2001-04-06 2002-04-05 Dispositif et procede destines a etre utilises en cryptographie quantique

Country Status (5)

Country Link
US (1) US7400724B2 (fr)
EP (1) EP1374475A2 (fr)
AU (1) AU2002338378A1 (fr)
DE (1) DE10117272B4 (fr)
WO (1) WO2002082714A2 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030063751A1 (en) * 2001-09-20 2003-04-03 Aiden Bruen Key agreement protocol based on network dynamics
JP4632652B2 (ja) * 2003-10-10 2011-02-16 日本電気株式会社 量子暗号鍵配布システム及びそれに用いる同期方法
US7974540B2 (en) * 2003-11-28 2011-07-05 Japan Science And Technology Agency Communication system and communication method using the same
US20060018476A1 (en) * 2004-06-23 2006-01-26 Nickel George H Key path generation and exchange of cryptographic keys using path length noise
US20070162743A1 (en) * 2006-01-12 2007-07-12 Savant Protection, Inc. Sliding acoustical signatures
WO2009054894A1 (fr) * 2007-10-23 2009-04-30 Bvp Holding, Inc. Dispositif d'entraînement de balancement, de rotation et de torsion du corps multidirectionnel avec des accessoires interchangeables et ajustables
EP3335368B1 (fr) * 2015-08-14 2022-08-03 Nokia Technologies Oy Système de distribution de clé quantique variable en continu sur puce avec multiplexage en polarisation et par répartition en fréquence
GB2559801B (en) * 2017-02-20 2021-04-28 Toshiba Kk An optical quantum communication system

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5243649A (en) * 1992-09-29 1993-09-07 The Johns Hopkins University Apparatus and method for quantum mechanical encryption for the transmission of secure communications
US5307410A (en) * 1993-05-25 1994-04-26 International Business Machines Corporation Interferometric quantum cryptographic key distribution system
CA2168851C (fr) * 1993-09-09 1999-11-02 Keith James Blow Systeme et methode de chiffrement quantique
JP3645261B2 (ja) * 1993-09-09 2005-05-11 ブリテイッシュ・テレコミュニケーションズ・パブリック・リミテッド・カンパニー 量子暗号を使用する多元接続ネットワークにおけるキー配送
GB9320793D0 (en) * 1993-10-08 1993-12-08 Secr Defence Cryptographic receiver
JP4064463B2 (ja) * 1996-05-22 2008-03-19 ブリティッシュ・テレコミュニケーションズ・パブリック・リミテッド・カンパニー 偏波に感応しない量子暗号用の方法および装置
US5732139A (en) * 1996-08-26 1998-03-24 Lo; Hoi-Kwong Quantum cryptographic system with reduced data loss
US5999285A (en) * 1997-05-23 1999-12-07 The United States Of America As Represented By The Secretary Of The Army Positive-operator-valued-measure receiver for quantum cryptography
US6188768B1 (en) * 1998-03-31 2001-02-13 International Business Machines Corporation Autocompensating quantum cryptographic key distribution system based on polarization splitting of light
DE19823849B4 (de) * 1998-05-28 2004-09-16 Deutsche Telekom Ag Verfahren und Vorrichtung zur Erzeugung von wahlweise Einzelphotonen oder Photonenpaaren in mindestens einem von zwei optischen Kanälen
DE19833330C2 (de) * 1998-07-24 2001-03-15 Deutsche Telekom Ag Quantenkryptographiesystem zur gesicherten Übertragung zufälliger Schlüssel unter Verwendung des Polarisationsstellverfahrens
US6289104B1 (en) * 1998-08-07 2001-09-11 Ilinois Institute Of Technology Free-space quantum cryptography system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO02082714A2 *

Also Published As

Publication number Publication date
WO2002082714A3 (fr) 2003-09-25
US7400724B2 (en) 2008-07-15
DE10117272B4 (de) 2005-04-28
DE10117272A1 (de) 2002-10-24
WO2002082714A2 (fr) 2002-10-17
US20040156502A1 (en) 2004-08-12
AU2002338378A1 (en) 2002-10-21

Similar Documents

Publication Publication Date Title
EP1029394B1 (fr) Procede pour produire un nombre aleatoire selon des principes de mecanique quantique, et generateur aleatoire
DE69432482T2 (de) Verfahren zur schlusselverteilung unter verwendung von quanten-kryptographie
US6424665B1 (en) Ultra-bright source of polarization-entangled photons
DE69415815T2 (de) System und verfahren zur schlüsselverteilung unter verwendung von quanten-kryptographie
DE69414864T2 (de) Schlüsselverteilung in einem netzwerk mit vielfachzugriff unter verwendung von quanten-kryptographie
DE60220083T2 (de) Kryptographische Kommunikationsvorrichtung
DE69309496T2 (de) System und verfahren zur schluesselverteilung unter verwendung von quanten-kryptographie
O’Sullivan-Hale et al. Pixel entanglement: experimental realization of optically entangled d= 3 and d= 6 qudits
AT505987B1 (de) Qkd-einrichtung
DE69414874T2 (de) Kryptographischer empfänger
DE69736856T2 (de) Überwachung von nichtlinearen Effekten in einem optischen Übertragungssystem
DE69408152T2 (de) System und verfahren zur quanten-kryptographie
DE112008003881B4 (de) System und Verfahren für die Quantenkryptographie
Liu et al. Experimental remote preparation of arbitrary photon polarization states
Rarity et al. Secure free-space key exchange to 1.9 km and beyond
JP6115387B2 (ja) 量子鍵配送用受信器及び単一光子検出器の使用方法
DE1616220B1 (de) Optisches Multiplexverfahren
DE69210506T2 (de) Frequenzmoduliertes kohärentes optisches Übertragungssystem mit kontinuierlicher Polarisationsverwürflung
US7492903B2 (en) Secret key distribution method and secret key distribution system
EP1374475A2 (fr) Dispositif et procede destines a etre utilises en cryptographie quantique
EP0975119B1 (fr) Système de cryptographie quantique pour la transmission d'une clé aléatoire en utilisant le procédé de polarisation
DE69914030T2 (de) Verfahren zur Messung der Polarisationsmodendispersion
DE69521515T2 (de) Quantenkryptographie
Ikuta et al. Efficient decoherence-free entanglement distribution over lossy quantum channels
Santos et al. Measurement of the degree of polarization entanglement through position interference

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20031027

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

AX Request for extension of the european patent

Extension state: AL LT LV MK RO SI

RIN1 Information on inventor provided before grant (corrected)

Inventor name: KURTSIEFER, CHRISTIAN11-05 KENT VALE APT., BLOCK

Inventor name: WEINFURTER, HARALD

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: QUTOOLS GMBH

17Q First examination report despatched

Effective date: 20071105

RIC1 Information provided on ipc code assigned before grant

Ipc: H04L 9/08 20060101AFI20120717BHEP

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20121206