A computerized record hash coding and linkage procedure to warrant epidemiological follow-up data security

A computerized record hash coding and linkage procedure is proposed to allow the chaining of medical information within the framework of epidemiological follow-up. Before their extraction, files are rendered anonymous using a one-way hash coding based on the SHA function, in order to respect the legislation on data privacy and security. To avoid dictionary attacks, two keys have been added to SHA coding. Once rendered anonymous, the linkage of patient information can be accomplished by the means of a statistical model, taking into account several identification variables.