xref: /titanic_41/usr/src/uts/common/gssapi/mechs/krb5/crypto/des/f_parity.c (revision 159d09a20817016f09b3ea28d1bdada4a336bb91)
1 /*
2  * These routines check and fix parity of encryption keys for the DES
3  * algorithm.
4  *
5  * They are a replacement for routines in key_parity.c, that don't require
6  * the table building that they do.
7  *
8  * Mark Eichin -- Cygnus Support
9  */
10 
11 
12 #include "des_int.h"
13 
14 /*
15  * des_fixup_key_parity: Forces odd parity per byte; parity is bits
16  *                       8,16,...64 in des order, implies 0, 8, 16, ...
17  *                       vax order.
18  */
19 #define smask(step) ((1<<step)-1)
20 #define pstep(x,step) (((x)&smask(step))^(((x)>>step)&smask(step)))
21 #define parity_char(x) pstep(pstep(pstep((x),4),2),1)
22 
23 void
mit_des_fixup_key_parity(mit_des_cblock key)24 mit_des_fixup_key_parity(mit_des_cblock key)
25 {
26     int i;
27     for (i=0; i<sizeof(mit_des_cblock); i++)
28       {
29 	key[i] &= 0xfe;
30 	key[i] |= 1^parity_char(key[i]);
31       }
32 
33     return;
34 }
35 
36 /*
37  * des_check_key_parity: returns true iff key has the correct des parity.
38  *                       See des_fix_key_parity for the definition of
39  *                       correct des parity.
40  */
41 int
mit_des_check_key_parity(mit_des_cblock key)42 mit_des_check_key_parity(mit_des_cblock key)
43 {
44     int i;
45 
46     for (i=0; i<sizeof(mit_des_cblock); i++)
47       {
48 	if((key[i] & 1) == parity_char(0xfe&key[i]))
49 	  {
50 	    return 0;
51 	  }
52       }
53 
54     return(1);
55 }
56 
57