Deutschetelekom Ag

Joerg Schwenk

Tobias Martin

Johannes Ueberberg

Ralf Schaffelhofer

Friedrich Toensing

Eva Saar

Wolfgang Oberndorfer

Stefan Heuser

Klaus Miethe

Christoph Schaaf

Jens Johann

Joachim Fingerholz

In a method for the secure, distributed generation of an encryption key for a cryptographic method, where the encryption key, as well as a public key are generated using deterministic methods from a large random number (seed), the seed (S) is generated on the user side by consulting variables known only to the user, and a public key (V) that is transmitted in advance from the trust center. Generation information suitable for generating the seed and, on the basis of which, the seed is able to be derived deterministically from the trust center, by consulting information known only to the center, is produced on the user side, and transmitted to the trust center to create the seed in parallel.

Method for the secure, distributed generation of an encryption key

A terminal device for using different services offered via a telecommunications network includes at lest one receiving device for image and sound information, at least one transmitting device for data which is used to select the received image and sound information, an input unit, a decoder for the image and sound information, and outputs for audio and video signals. A server for such terminal devices includes devices for connection to a telecommunications network, devices for carrying out authorization checks using the respective data received from a terminal device, and devices for receiving and processing service requests of the terminal devices. The services used may include television programs, such as pay TV and interactive television, and Internet applications.

Terminal device and method for using different services offered via a telecommunications network

A method for establishing a common key for a group of at least three subscribers includes using a publicly known mathematical number group and a higher order element of the group g&#x2208;G. In the first step, a message corresponding to Ni: =gmod p is sent by each subscriber to all other subscribers (Tj), (zi) being a random number chosen from the set (1, . . . , p-2) by a random number generator. In the second step, each subscriber (Ti) selects a transmission key kij:=(g)for each other subscriber (Tj) from the received message (g), with i&#x2260;j, for transmitting their random number (zi) to the subscribers (Tj). In the third step, the common key k is calculated as k:=f(z, z, . . . , zn) for each subscriber Ti.

Method for establishing a common key for a group of at least three subscribers

A process is described which can be used to generate a cryptographic key for a group of subscribers whose number is subject to change. The process can further provide that even after the group key has been established, subscribers can be removed from or added to the key directory without great effort.

Process for establishing a common cryptographic key for N subscribers

Verification of true authorship on the basis of digital watermarks is described. The digital watermark can be provided with the proof of identity id and/or with the hash value h(m) of the document and/or with a time value t.

Method for generating digital watermarks for electronic documents

A method for financing multimedia content through advertising includes playing back advertising blocks between uses of the content so to finance use of the content by the advertising. Code elements of a key are embedded in predefined locations in the advertising blocks, the key being configured for decryption of the content that follows. The embedded code elements are scanned and collected during the playback of the advertising blocks. The code elements are linked schematically to form the key. The content is encrypted using the key so that a use of the content depends on at least one of a subset of the code elements determined by the advertiser and the key.

Method for financing multimedia content through advertising

A method and device for relaying specific data, especially receiving rights, to a pay television terminal. The data originating from a transmitter is transmitted to the pay television terminal via a transmission medium with the application of mobile data carriers, especially chipcards. The pay television terminal temporarily stores specific data, and afterwards, a specific mobile data carrier is connected to the pay television terminal in a communicative manner. The receiving rights linked to said mobile data carriers are relayed and stored on the data carriers.

Method and device for routing of specific data, particularly receiving rights, in a pay-TV terminal

A method for establishing a common key for a group of at least three subscribers includes using a publicly known mathematical number group and a higher order element of the group g&#x3b5;G. In the first step, a message corresponding to Ni:=gmod p is sent by each subscriber to all other subscribers (Tj), (zi) being a random number chosen from the set (1, . . . , p&#x2212;2) by a random number generator. In the second step, each subscriber (Ti) selects a transmission key kij:=(gfor each other subscriber (Tj) from the received message (g), with i&#x2260;j, for transmitting their random number (zi) to the subscribers (Tj). In the third step, the common key k is calculated as k:=f(z1, z2, . . . , zn) for each subscriber Ti.

A method for key agreement for a cryptographically secured point-to-multipoint connection between a server and a plurality of clients includes altering, as a function of an identifier included in a first server message, a sequence of messages in a handshake initiating a secure socket layer protocol session. The identifier identifies the connection as an IP multicast connection. A MasterKey is generated using the server, the MasterKey being used to generate a session key for encrypting application data. The MasterKey is transmitted to the client.

Method for key agreement for a cryptographic secure point&#x2014;to&#x2014;multipoint connection

A billing method for requesting contents or data in a network in which the client or the person representing the client has a certificate for the billing method. Said certificate contains data that prove the client's identity and that facilitate establishment of a bill or statement. The Secure Socket Layer (SSL) protocol or a variant of the SSL protocol which allows display of a dialog box may be used for the client-server connection, using an SSL client certificate that contains an extension indicating that the certificate is suitable for the purpose of billing, the server transmitting the price for the required content or the data during the handshake protocol. A confirmation message that is also contained in the SSL protocol and that contains a digital signature is sent from the client to the server, said confirmation message confirming the previously transmitted price.

Billing method using SSL/TLS

A method for addressing terminals for receiving television programs subject to charge includes dividing the terminals into respective groups, each group having a respective group address. A respective identifier is assigned to each of the terminals of a group, each identifier being a respective binary vector. A data word and the respective group address of a first group is sent so as to address predetermined terminals of the first group. The data word is generated by logically combining the respective binary vectors of the terminals of the first group with a further binary vector, the further binary vector indicating the predetermined terminals.

Method for addressing terminals

A method for generating/regenerating an encryption key for a cryptographic method including the encryption key as well as a public key being generated using a predefined deterministic method from a large random number (seed), where the seed is only generated on the user side, and for which quantities available only to the user are consulted. Regeneration information (R), which is suitable for regenerating the seed and from which the seed is able to be derived deterministically by the trust center by linking only to information known to it, may be generated on the user side and stored so as to be secured against lost. In the event of loss of the encryption key, the seed may be reconstructed by the trust center by linking the regeneration information to the secret information.

Method for generating/regenerating an encryption key for a cryptographic method

The present invention provides a method for generating a common key between a central station and a group of subscribers, e.g., at least three subscribers, exhibit the same standard of security as the DH method.

Method for establishing a common key between a central station and a group of subscribers

A method for generating a personal identification number (PIN), made up of a number of N decimal digits, to be used for money cards and other devices requiring security, from a binary number having L digits, in particular from a binary code specific to an individual, the PINs are generated such that they are randomly uniformly distributed over the available number domain.

Method for generating identification numbers

A method for identifying betrayers of proprietary data which enables a betrayer, i.e., an authorized subscriber who has disclosed one of his partial keys to a third person without authorization, to be unequivocally identified. A respective subset of encryption keys is assigned to each authorized subscriber according to finite geometric structures and methods such that the necessary characteristic of the k-resilience used for identifying a betrayer is guaranteed. A betrayer search algorithm is used for the unequivocal identification of a betrayer. Coalitions of betrayers may also be unequivocally identified.

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Dieburg, Germany

Joerg Schwenk