@Article{Riv80a, author = { Ronald L. Rivest }, title = { ``Forwards and Backwards'' encryption }, pages = { 30--33 }, doi = { 10.1080/0161-118091854807 }, blocked = { pdf }, journal = { Cryptologia }, publisher = { Taylor \& Francis }, OPTyear = { 1980 }, OPTmonth = { January }, date = { 1980-01 }, volume = { 4 }, number = { 1 }, abstract = { I present here a variation on the use of pseudo-random sequences for encryption which is extremely resistant to probable-word analysis. Decrypting any small fragment of the message does not directly allow the cryptanalyst to read the rest of the message. }, }