SUBSTITUTION CIPHER TEXT-ENCODING AND UN-ENCODING SOFTWARE AND METHOD

A method or computer program for encoding or un-encoding data receives a keyword string and removes characters in the keyword string which are not in a pre-approved character set and duplicate characters to form a validated keyword. The validated keyword is sequenced with un-used characters of the pre-approved character set and formed into a cipher grid. Clear text may be encoded using an algorithm in combination with the cipher grid, and encoded text may be un-encoded to form clear text using a reverse algorithm in combination with the cipher grid.