Data compression in view of data sealing

Extended summary form only given. Security mechanisms are discussed in the context of a cryptographic mechanism to ensure data integrity and to provide proof of origin, i.e. to guarantee that the data originates from the `true sender´, using public-key (asymmetric) cryptosystems with the capability of digital signature. Because of possible attacks, the search for efficient and secure hash functions is an important open problem. Two methods are proposed, combining a hash function with compression algorithms