Boolean Ring Cryptography
This Demonstration shows an encryption code based on Le\:015bniewski's 16 Boolean ring forms for propositional functions of two arguments, also extended to 32 elements using filled circles. A plaintext consists of a sequence of elements from a Boolean ring and is encrypted using another sequence (the key) of the same length. Suppose the corresponding elements at position are and ; then the corresponding element of the encryption is . A receiver then decrypts the plaintext using the key: .
Le\:015bniewski, Mazurkiewicz and Sierpi\:0144ski helped the Polish army decode Soviet military communications. Their work was instrumental in the decisive 1920 defeat of Soviet invading forces in the suburbs of Warsaw .
 A. McFarland, J. McFarland and J. T. Smith, eds., Alfred Tarski, Early Work in Poland: Geometry and Teaching, New York: Birkhäuser, 2014 p. 9.