pc1_outputstream.java

JAVA加密算法之一

/* JAVA Port by Robert Neild November 1999 */

/* PC1 Cipher Algorithm ( Pukall Cipher 1 ) */
/* By Alexander PUKALL 1991 */
/* free code no restriction to use */
/* please include the name of the Author in the final software */
/* the Key is 128 bits */

/* Only the K zone change in the two routines */
/* You can create a single routine with the two parts in it */

import java.io.*;

public class PC1_OutputStream extends FilterOutputStream
{
   
      char ax,bx,cx,dx,si,tmp,x1a2,res,i,inter,cfc,cfd,compte;
      byte cle[] = new byte [17];               // holds key
      char x1a0[] = new char [8];
      short c;
      
      /**
       * Creates a PC1_OutputStream. Takes plain bytes, encrypts then
       * and writes them to the underlying output stream specified in
       * the constructor.
       *
       * @param out  The  output stream to decode.
       * @param password 16 byte encryption key
       */    
 
      public PC1_OutputStream (OutputStream out, byte[] password) {
	 super(out);
	 
	 System.arraycopy(password,0,cle,0,Math.min(16,password.length));
      }

      private void assemble()
      {
	 
	 x1a0[0]= (char) ( ( cle[0]*256 )+ cle[1]);
	 code();
	 inter=res;
	 
	 x1a0[1]= (char) (x1a0[0] ^ ( (cle[2]*256) + cle[3]));
	 code();
	 inter=(char) (inter^res);
	 
	 x1a0[2]= (char) (x1a0[1] ^ ( (cle[4]*256) + cle[5]));
	 code();
	 inter=(char) (inter^res);
	 
	 x1a0[3]= (char) (x1a0[2] ^ ( (cle[6]*256) + cle[7] ));
	 code();
	 inter=(char) (inter^res);
	 
	 x1a0[4]= (char) (x1a0[3] ^ ( (cle[8]*256) + cle[9] ));
	 code();
	 inter=(char) (inter^res);
	 
	 x1a0[5]= (char) (x1a0[4] ^ ( (cle[10]*256) + cle[11] ));
	 code();
	 inter=(char) (inter^res);
	 
	 x1a0[6]= (char) (x1a0[5] ^ ( (cle[12]*256) + cle[13] ));
	 code();
	 inter=(char) (inter^res);
	 
	 x1a0[7]= (char) (x1a0[6] ^ ( (cle[14]*256) + cle[15] ));
	 code();
	 inter=(char) (inter^res);
	 
	 i=0;
      }
      
      private void code()
      {
	 dx=(char) (x1a2+i);
	 ax=x1a0[i];
	 cx=0x015a;
	 bx=0x4e35;
	 
	 tmp=ax;
	 ax=si;
	 si=tmp;
	 
	 tmp=ax;
	 ax=dx;
	 dx=tmp;
	 
	 if (ax!=0) {
	    ax=(char) (ax*bx);
	 }

	 tmp=ax;
	 ax=cx;
	 cx=tmp;
	 
	 if (ax!=0)  {
	    ax=(char) (ax*si);
	    cx=(char) (ax+cx);
	 }

	 tmp=ax;
	 ax=si;
	 si=tmp;
	 ax=(char) (ax*bx);
	 dx=(char) (cx+dx);
	 
	 ax=(char) (ax+1);
	 
	 x1a2=dx;
	 x1a0[i]=ax;
	 
	 res=(char) (ax^dx);
	 i=(char) (i+1);
      }

      /**
       * Write out an encrypted byte
       * @see java.io.FilterOutputStream
       */    
      
      public void write(int c) throws IOException {
	 
	 assemble();
	 cfc=(char) (inter>>8);
	 cfd=(char) (inter&255); /* cfc^cfd = random byte */

	 /* K ZONE !!!!!!!!!!!!! */
	 /* here the mix of c and cle[compte] is before the encryption of c */

	 for (compte=0;compte<=15;compte++)
	 {
	    /* we mix the plaintext byte with the key */
	    
	    cle[compte]=(byte) (cle[compte]^c);
	 }

	 c = c ^ (cfc^cfd);
	 
	 out.write(c);  /* we write the crypted byte */
      }
      
}