XOR_encryption

Text XOR encryption James Newton wrote on encryption: Hi, The following handler encrypts a text of 10000 characters in under a second on my pentium II at 400 MHz. It should work safely with all standard ascii alphanumeric characters. I haven't tested fully with charToNum() < 49 or charToNum() > 122. If you find this useful, perhaps you could post it to the other lists that you cross-posted initially. Cheers, James ===================================================================== on encrypt(plainString, encryptString) ------------------------------ -- Returns a Xor-encrypted string, where each character of -- plainString is encoded according to the corresponding character -- of encryptString. If encryptString is not long enough, the same -- series of characters is used repeatedly. -- -- To unencode, simply re-encrypt the encrypted result using the -- original encrypt key. -- -- Example: -- x = encrypt("Handler written by James Newton", "using D8") -- put x -- -- "= -- E6 iE* -- I$M!KU= -- O*" -- put encrypt(x, "using D8") -- -- "Handler written by James Newton" --------------------------------------------------------------------- if not stringP(plainString) then return #invalidString else if not stringP(encryptString) then return plainString else if encryptString = "" then return plainString end if plainLength = the number of chars of plainString encryptLength = the number of chars of encryptString -- Ensure that encryptString is at least as long as plainString if encryptLength < plainLength then temp = encryptString shortFall = (plainLength / encryptLength) repeat while shortFall put temp after encryptString shortFall = shortFall - 1 end repeat end if -- Encrypt each character of plainString using the corresponding -- character of encryptString. If the plain character is the same -- as the encrypt character, no encryption occurs (the result of the -- encryption would be numToChar(0), which is coerced to any empty -- string). encryption = "" repeat while plainLength plainChar = plainString.char[1] plainNum = charToNum(plainChar) encryptNum = charToNum(encryptString.char[1]) if plainNum <> encryptNum then put numToChar(bitXor(plainNum, encryptNum)) after encryption else -- Use the non encrypted character rather than numToChar(0) put plainChar after encryption end if delete plainString.char[1] delete encryptString.char[1] plainLength = plainLength - 1 end repeat return encryption end encrypt