Description
This is an implementation of the high-strength ArcFour encryption algorithm, written using the Quartus Forth on-board compiler for the Palm series of handheld computers.
Source Code
\ arcfour implementation needs core-ext decimal : carray ( n "name" -- ) create chars allot does> ( n -- addr ) swap chars + ; 256 carray S 0 value j : j+! ( n -- ) j + 255 and to j ; : init-S ( -- ) 256 0 do i dup S c! loop ; : mix-S ( K-addr length -- ) 256 0 do \ j=j+S[i]+K[i modulo length] 2dup i swap mod chars + c@ i S c@ + j+! \ swap S[i] and S[j] j S c@ i S c@ j S c! i S c! loop 2drop ; : arcfourkey ( K-addr length -- ) init-S 0 to j mix-S ; : arcfour ( M-addr length -- ) 0 to j swap 1- swap 1+ 1 do \ j=j+S[i] i S c@ j+! \ swap S[i] and S[j] j S c@ i S c@ 2dup j S c! i S c! \ xor M[i-1] with S[j]+S[i] + 255 and S c@ over i chars + dup c@ rot xor swap c! loop drop ; create MD5digest 16 chars allot : MD5 ( c-addr u -- c-addr2 16 ) MD5digest >abs 2swap swap >abs EncDigestMD5 2drop ( * fix * ) MD5digest 16 ;
Program Notes
The '
needs core-ext' at the top of the file is specific to Quartus Forth, and the MD5 definition at the bottom of the file calls a specific routine in the Palm OS; the rest of the file, however, is Standard Forth.