IRREVERSIBLE ENCRYPTION METHOD BY GENERATION OF POLYNOMIALS

Patient follow up, within the framework of epidemiological studies, po ses the problem of linking nominal files. An encryption method of iden tity is proposed to allow the linkage of medical information on the sa me patient while respecting the confidentiality of medical data. In co ntrast with most encryption algorithms, the proposed method is mathema tically irreversible in response to the requirement of the French Nati onal Commission of Computerized Information Security which demands tha t the cryptosystem must not be decipherable even by the legitimate rec ipient. In order to prevent deciphering by frequency analysis, the pro posed method introduces polynomial operations so that neither indicati on concerning the length of the string nor a possible repetition of ch aracters can be obtained by code disclosure. The security of the syste m is reinforced by the use of two keys, the first one to be defined by the producers of information and the second one by the recipient so t hat nobody can decrypt the enciphered text.