Method for protecting a volatile file using a single hash

Abstract From the Canadian patent

The disclosed methodology permits an insecure computing system to safely perform high security electronic financial transactions. The present invention permits the hash of a file to be taken on an incremental basis. It permits any part of the file to be changed while allowing a new aggregate hash to be computed based on the revised file portion and the prior total hash. The aggregate hash is readily updatable with each record revision without having to recompute the hash of the entire file in accordance with conventional techniques. These objectives using two functions. The first function is an effective one-way hash function "H" for which it is computationally impossible to find two data …