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
35 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)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