rc4.txt

经典加密算法的VISUAL BASIC 源代码集合,包括RC4,MD5 ,RAS 等

Private  Function  RC4(inp  As  String,  key  As  String)  As  String  
       Dim  S(0  To  255)  As  Byte,  K(0  To  255)  As  Byte,  i  As  Long  
       Dim  j  As  Long,  temp  As  Byte,  Y  As  Byte,  t  As  Long,  x  As  Long  
       Dim  Outp  As  String  
       For  i  =  0  To  255  
               S(i)  =  i  
       Next  
       j  =  1  
       For  i  =  0  To  255  
               If  j  >  Len(key)  Then  j  =  1  
               K(i)  =  Asc(Mid(key,  j,  1))  
               j  =  j  +  1  
       Next  i  
       j  =  0  
       For  i  =  0  To  255  
               j  =  (j  +  S(i)  +  K(i))  Mod  256  
               temp  =  S(i)  
               S(i)  =  S(j)  
               S(j)  =  temp  
       Next  i  
       i  =  0  
       j  =  0  
       For  x  =  1  To  Len(inp)  
               i  =  (i  +  1)  Mod  256  
               j  =  (j  +  S(i))  Mod  256  
               temp  =  S(i)  
               S(i)  =  S(j)  
               S(j)  =  temp  
               t  =  (S(i)  +  (S(j)  Mod  256))  Mod  256  
               Y  =  S(t)  
               Outp  =  Outp  &  Chr(Asc(Mid(inp,  x,  1))  Xor  Y)  
       Next  x  
       RC4  =  Outp  
End  Function