RC4 Encryption Algorithm Script

 

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RC4 is a stream cipher. Using a password, a string may be encrypted. By running the encrypted text through the same algorithm, the string becomes readable only when the password is the same as the one used during encryption. Great for protecting your high score tables or prefs files from prying eyes and itchy hacker fingers! ;) PsychicParrot.

Download PC Source

-- RC4 Algorithm -- -- Adapted from VB code written by Luke Bailey -- Copyright 2002 PsychicParrot -- oracle@psychicparrot.com -- -- You are welcome to use this script as you wish, but keep these comments intact please! -- global sbox,ke,scn,srn,tempswap,a,b global temp,i,j,k,cipherkey,cipher on beginsprite      sbox=[]   ke=[]    end on Security_RC4Initialise(strpwd)      cipher=EMPTY   intlength = strpwd.length   sbox=[]   ke=[]      repeat with a=1 to 255          ke[a]=chartonum(strpwd.char[(a mod intlength+1)..(a mod intlength+1)])     sbox[a]=a        end repeat      b=0      repeat with a=1 to 255     b=((b+sbox[a]+ke[a]) mod 255)     tempswap = sbox[a]     sbox[a]=sbox[b]     sbox[b]=tempswap   end repeat    end on Security_RC4(plaintxt)      i=0   j=0      repeat with a=1 to plaintxt.length          i=((i+1) mod 255)     j=((j+sbox[i]) mod 255)     temp=sbox[i]     sbox[i]=sbox[j]     sbox[j]=temp     k=sbox[((sbox[i]+sbox[j]) mod 255)]     cipherby=bitXor(chartonum(plaintxt.char[a..a]),k)     cipher=cipher&numtochar(cipherby)        end repeat      RETURN cipher    end