xref: /openssl/crypto/des/qud_cksm.c (revision 33388b44)
1 /*
2  * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
3  *
4  * Licensed under the Apache License 2.0 (the "License").  You may not use
5  * this file except in compliance with the License.  You can obtain a copy
6  * in the file LICENSE in the source distribution or at
7  * https://www.openssl.org/source/license.html
8  */
9 
10 /*
11  * From "Message Authentication" R.R. Jueneman, S.M. Matyas, C.H. Meyer IEEE
12  * Communications Magazine Sept 1985 Vol. 23 No. 9 p 29-40 This module in
13  * only based on the code in this paper and is almost definitely not the same
14  * as the MIT implementation.
15  */
16 
17 /*
18  * DES low level APIs are deprecated for public use, but still ok for internal
19  * use.
20  */
21 #include "internal/deprecated.h"
22 
23 #include "des_local.h"
24 
25 #define Q_B0(a) (((DES_LONG)(a)))
26 #define Q_B1(a) (((DES_LONG)(a))<<8)
27 #define Q_B2(a) (((DES_LONG)(a))<<16)
28 #define Q_B3(a) (((DES_LONG)(a))<<24)
29 
30 /* used to scramble things a bit */
31 /* Got the value MIT uses via brute force :-) 2/10/90 eay */
32 #define NOISE   ((DES_LONG)83653421L)
33 
DES_quad_cksum(const unsigned char * input,DES_cblock output[],long length,int out_count,DES_cblock * seed)34 DES_LONG DES_quad_cksum(const unsigned char *input, DES_cblock output[],
35                         long length, int out_count, DES_cblock *seed)
36 {
37     DES_LONG z0, z1, t0, t1;
38     int i;
39     long l;
40     const unsigned char *cp;
41     DES_LONG *lp;
42 
43     if (out_count < 1)
44         out_count = 1;
45     lp = (DES_LONG *)&(output[0])[0];
46 
47     z0 = Q_B0((*seed)[0]) | Q_B1((*seed)[1]) | Q_B2((*seed)[2]) |
48         Q_B3((*seed)[3]);
49     z1 = Q_B0((*seed)[4]) | Q_B1((*seed)[5]) | Q_B2((*seed)[6]) |
50         Q_B3((*seed)[7]);
51 
52     for (i = 0; ((i < 4) && (i < out_count)); i++) {
53         cp = input;
54         l = length;
55         while (l > 0) {
56             if (l > 1) {
57                 t0 = (DES_LONG)(*(cp++));
58                 t0 |= (DES_LONG)Q_B1(*(cp++));
59                 l--;
60             } else
61                 t0 = (DES_LONG)(*(cp++));
62             l--;
63             /* add */
64             t0 += z0;
65             t0 &= 0xffffffffL;
66             t1 = z1;
67             /* square, well sort of square */
68             z0 = ((((t0 * t0) & 0xffffffffL) + ((t1 * t1) & 0xffffffffL))
69                   & 0xffffffffL) % 0x7fffffffL;
70             z1 = ((t0 * ((t1 + NOISE) & 0xffffffffL)) & 0xffffffffL) %
71                 0x7fffffffL;
72         }
73         if (lp != NULL) {
74             /*
75              * The MIT library assumes that the checksum is composed of
76              * 2*out_count 32 bit ints
77              */
78             *lp++ = z0;
79             *lp++ = z1;
80         }
81     }
82     return z0;
83 }
84