des_locl.h

DES密码体制的安全性应该不依赖于算法的保密

/* lib/des/des_locl.h */
/* Copyright (C) 1995-1996 Eric Young ([e-mail])
 * All rights reserved.
 *
 */

#ifndef HEADER_DES_LOCL_H
#define HEADER_DES_LOCL_H

#include "des_ecb.h"

#undef DES_PTR

#ifdef __STDC__
#undef NOPROTO
#endif

#define ITERATIONS 16
#define HALF_ITERATIONS 8

/* used in des_read and des_write */
#define MAXWRITE	(1024*16)
#define BSIZE		(MAXWRITE+4)

#define c2l(c,l)	(l =((DES_LONG)(*((c)++)))    , \
			 l|=((DES_LONG)(*((c)++)))<< 8L, \
			 l|=((DES_LONG)(*((c)++)))<<16L, \
			 l|=((DES_LONG)(*((c)++)))<<24L)

/* NOTE - c is not incremented as per c2l */
#define c2ln(c,l1,l2,n)	{ \
			c+=n; \
			l1=l2=0; \
			switch (n) { \
			case 8: l2 =((DES_LONG)(*(--(c))))<<24L; \
			case 7: l2|=((DES_LONG)(*(--(c))))<<16L; \
			case 6: l2|=((DES_LONG)(*(--(c))))<< 8L; \
			case 5: l2|=((DES_LONG)(*(--(c))));     \
			case 4: l1 =((DES_LONG)(*(--(c))))<<24L; \
			case 3: l1|=((DES_LONG)(*(--(c))))<<16L; \
			case 2: l1|=((DES_LONG)(*(--(c))))<< 8L; \
			case 1: l1|=((DES_LONG)(*(--(c))));     \
				} \
			}

#define l2c(l,c)	(*((c)++)=(unsigned char)(((l)     )&0xff), \
			 *((c)++)=(unsigned char)(((l)>> 8L)&0xff), \
			 *((c)++)=(unsigned char)(((l)>>16L)&0xff), \
			 *((c)++)=(unsigned char)(((l)>>24L)&0xff))

/* replacements for htonl and ntohl since I have no idea what to do
 * when faced with machines with 8 byte longs. */
#define HDRSIZE 4

#define n2l(c,l)	(l =((DES_LONG)(*((c)++)))<<24L, \
			 l|=((DES_LONG)(*((c)++)))<<16L, \
			 l|=((DES_LONG)(*((c)++)))<< 8L, \
			 l|=((DES_LONG)(*((c)++))))

#define l2n(l,c)	(*((c)++)=(unsigned char)(((l)>>24L)&0xff), \
			 *((c)++)=(unsigned char)(((l)>>16L)&0xff), \
			 *((c)++)=(unsigned char)(((l)>> 8L)&0xff), \
			 *((c)++)=(unsigned char)(((l)     )&0xff))

/* NOTE - c is not incremented as per l2c */
#define l2cn(l1,l2,c,n)	{ \
			c+=n; \
			switch (n) { \
			case 8: *(--(c))=(unsigned char)(((l2)>>24L)&0xff); \
			case 7: *(--(c))=(unsigned char)(((l2)>>16L)&0xff); \
			case 6: *(--(c))=(unsigned char)(((l2)>> 8L)&0xff); \
			case 5: *(--(c))=(unsigned char)(((l2)     )&0xff); \
			case 4: *(--(c))=(unsigned char)(((l1)>>24L)&0xff); \
			case 3: *(--(c))=(unsigned char)(((l1)>>16L)&0xff); \
			case 2: *(--(c))=(unsigned char)(((l1)>> 8L)&0xff); \
			case 1: *(--(c))=(unsigned char)(((l1)     )&0xff); \
				} \
			}

#define	ROTATE(a,n)	(((a)>>(n))+((a)<<(32-(n))))

/* The changes to this macro may help or hinder, depending on the
 * compiler and the achitecture.  gcc2 always seems to do well :-).
 * Inspired by Dana How <[e-mail]>
 * DO NOT use the alternative version on machines with 8 byte longs.
 * It does not seem to work on the Alpha, even when DES_LONG is 4
 * bytes, probably an issue of accessing non-word aligned objects :-( */
#ifdef DES_PTR

#define D_ENCRYPT(L,R,S) { \
	u=((R^s[S  ])<<2);	\
	t= R^s[S+1]; \
	t=ROTATE(t,2); \
	L^= (\
	*(DES_LONG *)((unsigned char *)des_SP+0x100+((t    )&0xfc))+ \
	*(DES_LONG *)((unsigned char *)des_SP+0x300+((t>> 8)&0xfc))+ \
	*(DES_LONG *)((unsigned char *)des_SP+0x500+((t>>16)&0xfc))+ \
	*(DES_LONG *)((unsigned char *)des_SP+0x700+((t>>24)&0xfc))+ \
	*(DES_LONG *)((unsigned char *)des_SP      +((u    )&0xfc))+ \
	*(DES_LONG *)((unsigned char *)des_SP+0x200+((u>> 8)&0xfc))+ \
	*(DES_LONG *)((unsigned char *)des_SP+0x400+((u>>16)&0xfc))+ \
	*(DES_LONG *)((unsigned char *)des_SP+0x600+((u>>24)&0xfc))); }
#else /* original version */
#ifdef undef
#define D_ENCRYPT(L,R,S)	\
	U.l=R^s[S+1]; \
	T.s[0]=((U.s[0]>>4)|(U.s[1]<<12))&0x3f3f; \
	T.s[1]=((U.s[1]>>4)|(U.s[0]<<12))&0x3f3f; \
	U.l=(R^s[S  ])&0x3f3f3f3fL; \
	L^=	des_SPtrans[1][(T.c[0])]| \
		des_SPtrans[3][(T.c[1])]| \
		des_SPtrans[5][(T.c[2])]| \
		des_SPtrans[7][(T.c[3])]| \
		des_SPtrans[0][(U.c[0])]| \
		des_SPtrans[2][(U.c[1])]| \
		des_SPtrans[4][(U.c[2])]| \
		des_SPtrans[6][(U.c[3])];
#else
#define D_ENCRYPT(Q,R,S) {\
	u=(R^s[S  ]); \
	t=R^s[S+1]; \
	t=ROTATE(t,4); \
	Q^=	des_SPtrans[1][(t     )&0x3f]| \
		des_SPtrans[3][(t>> 8L)&0x3f]| \
		des_SPtrans[5][(t>>16L)&0x3f]| \
		des_SPtrans[7][(t>>24L)&0x3f]| \
		des_SPtrans[0][(u     )&0x3f]| \
		des_SPtrans[2][(u>> 8L)&0x3f]| \
		des_SPtrans[4][(u>>16L)&0x3f]| \
		des_SPtrans[6][(u>>24L)&0x3f]; }
#endif
#endif

	/* IP and FP
	 * The problem is more of a geometric problem that random bit fiddling.
	 0  1  2  3  4  5  6  7      62 54 46 38 30 22 14  6
	 8  9 10 11 12 13 14 15      60 52 44 36 28 20 12  4
	16 17 18 19 20 21 22 23      58 50 42 34 26 18 10  2
	24 25 26 27 28 29 30 31  to  56 48 40 32 24 16  8  0

	32 33 34 35 36 37 38 39      63 55 47 39 31 23 15  7
	40 41 42 43 44 45 46 47      61 53 45 37 29 21 13  5
	48 49 50 51 52 53 54 55      59 51 43 35 27 19 11  3
	56 57 58 59 60 61 62 63      57 49 41 33 25 17  9  1

	The output has been subject to swaps of the form
	0 1 -> 3 1 but the odd and even bits have been put into
	2 3    2 0
	different words.  The main trick is to remember that
	t=((l>>size)^r)&(mask);
	r^=t;
	l^=(t<<size);
	can be used to swap and move bits between words.

	So l =  0  1  2  3  r = 16 17 18 19
	        4  5  6  7      20 21 22 23
	        8  9 10 11      24 25 26 27
	       12 13 14 15      28 29 30 31
	becomes (for size == 2 and mask == 0x3333)
	   t =   2^16  3^17 -- --   l =  0  1 16 17  r =  2  3 18 19
		 6^20  7^21 -- --        4  5 20 21       6  7 22 23
		10^24 11^25 -- --        8  9 24 25      10 11 24 25
		14^28 15^29 -- --       12 13 28 29      14 15 28 29

	Thanks for hints from Richard Outerbridge - he told me IP&FP
	could be done in 15 xor, 10 shifts and 5 ands.
	When I finally started to think of the problem in 2D
	I first got ~42 operations without xors.  When I remembered
	how to use xors :-) I got it to its final state.
	*/
#define PERM_OP(a,b,t,n,m) ((t)=((((a)>>(n))^(b))&(m)),\
	(b)^=(t),\
	(a)^=((t)<<(n)))

#define IP(l,r) \
	{ \
	register DES_LONG tt; \
	PERM_OP(r,l,tt, 4,0x0f0f0f0fL); \
	PERM_OP(l,r,tt,16,0x0000ffffL); \
	PERM_OP(r,l,tt, 2,0x33333333L); \
	PERM_OP(l,r,tt, 8,0x00ff00ffL); \
	PERM_OP(r,l,tt, 1,0x55555555L); \
	}

#define FP(l,r) \
	{ \
	register DES_LONG tt; \
	PERM_OP(l,r,tt, 1,0x55555555L); \
	PERM_OP(r,l,tt, 8,0x00ff00ffL); \
	PERM_OP(l,r,tt, 2,0x33333333L); \
	PERM_OP(r,l,tt,16,0x0000ffffL); \
	PERM_OP(l,r,tt, 4,0x0f0f0f0fL); \
	}
#endif