Abstract: A method for checking the availability and integrity of a data object stored on a plurality of servers and having a number N of data words. For the distributed storage on the servers, the data object is fragmented. Each fragment is transmitted to and stored on one server. To check the availability and integrity of the fragments stored on the servers, the same random number is sent from an auditor unit to the servers. A checksum is created by the servers, in each case modified by application of the random number to the data of the respective fragment, and the checksum is transmitted to the auditor unit. The auditor unit uses the consistency check to determine whether the individual checksums sent by the servers are consistent and, if this is the case, establishes the availability and integrity of the data.

Abstract: A method creates and distributes cryptographic keys for securing communication at two terminals. Signals for creating correlated values in the two terminals are distributed via a first communication channel burdened with error, and the correlated values are present as keys. A checksum is formed on the basis of the first key present in the first terminal and the checksum is transferred to the second terminal via a second communication channel. A second checksum is formed on the basis of the second key present, and information derived from the two checksums is transferred via the second communication channel to a server. Based on the information derived from the checksums, the server determines a correction value, which, when applied to one or both keys, brings the keys into correspondence. The correction value is transferred to one or both terminals via the second communication channel and is applied to one or both keys.

Abstract: A method for checking the availability and integrity of a data object stored on a plurality of servers and having a number N of data words. For the distributed storage on the servers, the data object is fragmented. Each fragment is transmitted to and stored on one server. To check the availability and integrity of the fragments stored on the servers, the same random number is sent from an auditor unit to the servers. A checksum is created by the servers, in each case modified by application of the random number to the data of the respective fragment, and the checksum is transmitted to the auditor unit. The auditor unit uses the consistency check to determine whether the individual checksums sent by the servers are consistent and, if this is the case, establishes the availability and integrity of the data.