Deutschetelekom Ag

Eric Hildebrandt

Wolfgang Dultz

Heidrun Schmitzer

Gisela Dultz

Leonid Beresnev

A method and system for the secure transmission of messages between at least two users of a telecommunications network, using a secret, random binary encryption key, which is used once for encryption. The key is generated in a key generator recorded on at least two portable data media, such as CDs, and then output in this form to the users, each of whom receives one data medium containing the recorded key. The key is not stored in any other location. The users insert the recorded key media into reading devices, which are respectively assigned to telecommunications equipment, e.g., telephones, fax machines, or PCs, employed by the users. When a connection is established, logistics devices, which are also assigned to the telecommunications equipment, check whether the keys were entered properly and whether they correspond to each other. The logistics devices also synchronize the entered keys, or at least portions of the keys, when the information to be transmitted is encrypted and decrypted.

Method for the secure transmission of messages

A method and arrangement for generating binary sequences of random numbers uses the principle of random selection of the path of photons on a beam splitter and generating a random number by using two detectors (D, D) downstream from a beam splitter (ST). To generate photons, a light source (L) of a low power is used, and an additional beam splitter (ST) is connected upstream from the beam splitter (ST). The photons emitted by the light source (L) during a predefined measurement time are split by the beam splitters (ST, ST) arranged one after the other in the beam path of the light source (L). The random sequence is generated when the splitting of the photons matches a predefined photon scheme.

Method and arrangement for generating binary sequences of random numbers

A quantum cryptography system using electrooptical liquid crystal modulators which change the polarization and which are designed as electrically rotatable retardation plates whose two birefringent axes are rotated by the applied electrical field around an angle &thgr; which depends on the strength of this field. A &lgr;/2 retardation plate rotates the elliptically polarized light striking the plate around an angle 2&thgr; at speeds in the microsecond range. The quantum cryptography system can be used for interception-proof data transmission over transmission links that are accessible to the public.

Quantum cryptography system for a secure transmission of random keys using a polarization setting method

A method and an apparatus for generating a random number on a quantum-mechanics machanics basis using the fundamentally random choice of path of a quantum particle on a beam splitter. Detectors are provided for capturing the particles being assigned to the outputs of the beam splitter. The detectors or their counting events represent different number values of the random number, or random number sequence. The generation of a multi-particle state in the output channel of the beam splitter, and thus of several particles which impact on a detector (D , D &prime;, D , D &prime;), significantly and advantageously increases the response probability of the detector and thus the probability of obtaining a useable counting event for every multi-particle state generated by the particle source. In this way a random sequence can be obtained more rapidly and more reliably than with single-particle detection.

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Frankfurt-am-Main, Germany

Eric Hildebrandt