alfcrypto.rb

#!/usr/bin/ruby

module Alf
    def pc1(key, src, decryption=true)
        sum1 = 0
        sum2 = 0
        keyXorVal = 0
        if key.length !=16
            print "Bad key length!\n"
            return nil
        end    

        wkey = []
        for i in 0...8 do 
            wkey << (key[i*2].unpack('C')[0]<<8 | key[i*2+1].unpack('C')[0])
        end

        dst = ""
        for i in 0...src.length do
            temp1 = 0
            byteXorVal = 0
            for j in 0...8 do 
                temp1 ^= wkey[j]
                sum2  = (sum2+j)*20021 + sum1
                sum1  = (temp1*346)&0xFFFF
                sum2  = (sum2+sum1)&0xFFFF
                temp1 = (temp1*20021+1)&0xFFFF
                byteXorVal ^= temp1 ^ sum2
            end
            curByte = src[i].ord
            if decryption == false
                keyXorVal = curByte * 257
            end

            curByte = ((curByte ^ (byteXorVal >> 8)) ^ byteXorVal) & 0xFF
            if decryption == true
                keyXorVal = curByte * 257
            end
            for j in 0...8
                wkey[j] ^= keyXorVal
            end
            dst += curByte.chr
        end

        return dst
    end
end