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 #pragma ident "%Z%%M% %I% %E% SMI"
32 /*LINTLIBRARY*/
33
34 #include <sys/types.h>
35
36 void
_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 _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)
38 {
39 /* EXPORT DELETE START */
40 int i, ii;
41 int t, j, k;
42 char t2;
43
44 /*
45 * First, permute the bits in the input
46 */
47 for (j = 0; j < 64; j++)
48 L[j] = block[IP[j]-1];
49 /*
50 * Perform a decryption operation 16 times.
51 */
52 for (ii = 0; ii < 16; ii++) {
53 i = 15-ii;
54 /*
55 * Save the R array,
56 * which will be the new L.
57 */
58 for (j = 0; j < 32; j++)
59 tempL[j] = R[j];
60 /*
61 * Expand R to 48 bits using the E selector;
62 * exclusive-or with the current key bits.
63 */
64 for (j = 0; j < 48; j++)
65 preS[j] = R[E[j]-1] ^ KS[i][j];
66 /*
67 * The pre-select bits are now considered
68 * in 8 groups of 6 bits each.
69 * The 8 selection functions map these
70 * 6-bit quantities into 4-bit quantities
71 * and the results permuted
72 * to make an f(R, K).
73 * The indexing into the selection functions
74 * is peculiar; it could be simplified by
75 * rewriting the tables.
76 */
77 for (j = 0; j < 8; j++) {
78 t = 6*j;
79 k = S[j][(preS[t+0]<<5)+
80 (preS[t+1]<<3)+
81 (preS[t+2]<<2)+
82 (preS[t+3]<<1)+
83 (preS[t+4]<<0)+
84 (preS[t+5]<<4)];
85 t = 4*j;
86 f[t+0] = (k>>3)&01;
87 f[t+1] = (k>>2)&01;
88 f[t+2] = (k>>1)&01;
89 f[t+3] = (k>>0)&01;
90 }
91 /*
92 * The new R is L ^ f(R, K).
93 * The f here has to be permuted first, though.
94 */
95 for (j = 0; j < 32; j++)
96 R[j] = L[j] ^ f[P[j]-1];
97 /*
98 * Finally, the new L (the original R)
99 * is copied back.
100 */
101 for (j = 0; j < 32; j++)
102 L[j] = tempL[j];
103 }
104 /*
105 * The output L and R are reversed.
106 */
107 for (j = 0; j < 32; j++) {
108 t2 = L[j];
109 L[j] = R[j];
110 R[j] = t2;
111 }
112 /*
113 * The final output
114 * gets the inverse permutation of the very original.
115 */
116 for (j = 0; j < 64; j++)
117 block[j] = L[FP[j]-1];
118 /* EXPORT DELETE END */
119 }
120