1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*	Copyright (c) 1988 AT&T	*/
23/*	  All Rights Reserved  	*/
24
25
26/*
27 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
28 * Use is subject to license terms.
29 */
30
31/*LINTLIBRARY*/
32
33#include <sys/types.h>
34
35void
36_des_decrypt1(char *block, char *L, char *IP, char *R, char *preS, char *E, char KS[][48], char S[][64], char *f, char *tempL, char *P, char *FP)
37{
38	int	i, ii;
39	int	t, j, k;
40	char	t2;
41
42	/*
43	 * First, permute the bits in the input
44	 */
45	for (j = 0; j < 64; j++)
46		L[j] = block[IP[j]-1];
47	/*
48	 * Perform a decryption operation 16 times.
49	 */
50	for (ii = 0; ii < 16; ii++) {
51		i = 15-ii;
52		/*
53		 * Save the R array,
54		 * which will be the new L.
55		 */
56		for (j = 0; j < 32; j++)
57			tempL[j] = R[j];
58		/*
59		 * Expand R to 48 bits using the E selector;
60		 * exclusive-or with the current key bits.
61		 */
62		for (j = 0; j < 48; j++)
63			preS[j] = R[E[j]-1] ^ KS[i][j];
64		/*
65		 * The pre-select bits are now considered
66		 * in 8 groups of 6 bits each.
67		 * The 8 selection functions map these
68		 * 6-bit quantities into 4-bit quantities
69		 * and the results permuted
70		 * to make an f(R, K).
71		 * The indexing into the selection functions
72		 * is peculiar; it could be simplified by
73		 * rewriting the tables.
74		 */
75		for (j = 0; j < 8; j++) {
76			t = 6*j;
77			k = S[j][(preS[t+0]<<5)+
78				(preS[t+1]<<3)+
79				(preS[t+2]<<2)+
80				(preS[t+3]<<1)+
81				(preS[t+4]<<0)+
82				(preS[t+5]<<4)];
83			t = 4*j;
84			f[t+0] = (k>>3)&01;
85			f[t+1] = (k>>2)&01;
86			f[t+2] = (k>>1)&01;
87			f[t+3] = (k>>0)&01;
88		}
89		/*
90		 * The new R is L ^ f(R, K).
91		 * The f here has to be permuted first, though.
92		 */
93		for (j = 0; j < 32; j++)
94			R[j] = L[j] ^ f[P[j]-1];
95		/*
96		 * Finally, the new L (the original R)
97		 * is copied back.
98		 */
99		for (j = 0; j < 32; j++)
100			L[j] = tempL[j];
101	}
102	/*
103	 * The output L and R are reversed.
104	 */
105	for (j = 0; j < 32; j++) {
106		t2 = L[j];
107		L[j] = R[j];
108		R[j] = t2;
109	}
110	/*
111	 * The final output
112	 * gets the inverse permutation of the very original.
113	 */
114	for (j = 0; j < 64; j++)
115		block[j] = L[FP[j]-1];
116}
117