Abstract: A method for securing a transaction in a reputation system includes the following steps: authenticating a user vis-à-vis an end device by means of an electronic proof of identity for releasing authentication data for the digital identity that are stored on the end device, and authenticating the digital pseudonym assigned to the user vis-à-vis the reputation system by means of the end device while employing the stored authentication data pertaining to the digital pseudonym. The electronic proof of identity can be present as an electronic identity card in the form of a portable data carrier.

Abstract: A method for operating a communication system comprises a transponder having at least one antenna, in particular in the form of a portable data carrier, and a reading device having at least one antenna. The reading device is configured to exchange data with the transponder. An exchange of data between the transponder and the reading device is possible within a predetermined range. A measurement and evaluation is effected of the time of a command transmitted from the reading device to the transponder and the receipt of a corresponding response of the transponder by the reading device. In so doing, a processing is effected of a card-individual length of time T_icc, wherein the card-individual length of time T_icc specifies how long the transponder takes for the receipt and the processing of a command received from the reading device and the sending of a corresponding response.

Abstract: A method for securing a transaction in a reputation system includes the following steps: authenticating a user vis-à-vis an end device by means of an electronic proof of identity for releasing authentication data for the digital identity that are stored on the end device, and authenticating the digital pseudonym assigned to the user vis-à-vis the reputation system by means of the end device while employing the stored authentication data pertaining to the digital pseudonym. The electronic proof of identity can be present as an electronic identity card in the form of a portable data carrier.

Abstract: A method for operating a communication system comprises a transponder having at least one antenna, in particular in the form of a portable data carrier, and a reading device having at least one antenna. The reading device is configured to exchange data with the transponder. An exchange of data between the transponder and the reading device is possible within a predetermined range. A measurement and evaluation is effected of the time of a command transmitted from the reading device to the transponder and the receipt of a corresponding response of the transponder by the reading device. In so doing, a processing is effected of a card-individual length of time T_icc, wherein the card-individual length of time T_icc specifies how long the transponder takes for the receipt and the processing of a command received from the reading device and the sending of a corresponding response.

Abstract: In a method for establishing a secure communication channel between a portable data carrier (10) and a terminal on the basis of an asymmetric cryptosystem, a value (X; Y; V; W) derived from a public key (PKD; PKT) of the cryptosystem is displayed on a display device (40) of the data carrier (10).

Abstract: A method and system for challenge-response authentication are provided. Challenge data are transferred within an anti-collision loop from a reading device to a transponder by means of one or more commands of an anti-collision method, with the one or more commands serving to determine transponder identification data. In the one or more commands respective challenge data are contained in a data field that is used for specifying transponder identification data, wherein it is indicated to the transponder by a parameter value in the at least one of the one or more commands that the data field of the one or more commands contains challenge data instead of transponder date. The transponder recognizes with the help of the parameter value that in the received one or more commands challenge data are contained. The transponder processes the transferred challenge data based on the challenge response authentication.

Abstract: In a method for establishing a secure communication channel between a portable data carrier (10) and a terminal on the basis of an asymmetric cryptosystem, a value (X; Y; V; W) derived from a public key (PKD; PKT) of the cryptosystem is displayed on a display device (40) of the data carrier (10).

Abstract: A method for challenge-response authentication between a reading device and a transponder based on a contactless data transmission, according to which challenge data (CH) are transferred within an anti-collision loop from the reading device to the transponder by means of one or several commands (AC) of an anti-collision method, with the command or commands (AC) serving to determine transponder identification data. In the command or commands (AC) respective challenge data (CH) are contained in a data field (D1) that is used for specifying transponder identification data (UID), wherein it is indicated to the transponder by a parameter value (NVB) in the command or at least one of the commands (AC) that the data field (D1) of the command or commands (AC) contains challenge data (CH) instead of transponder date (UID).

Abstract: The invention relates to a method for personalizing a security element (SE) of a mobile end device (EG), in particular in the form of a smart card chip of a communication end device. The invention comprises the pre-personalizing of the security element (SE) within the framework of its production process and the final personalizing of the security element (SE) upon the first-time use of the end device (EG) by a user (N), wherein a communication link is established between the end device (EG) and a trust center (TC) of a communication network operator. Within the framework of the pre-personalization of the security element (SE), a master key (MK) unique to the security element (SE) is ascertained and transmitted to the trust center (TC). Within the frame-work of the final personalization of the security element (SE), personal data of the user are transmitted upon the first-time use of the end device (EG) to the trust center (TC) and linked there with the master key (MK) to form a modified master key (MK).