1 #pragma ident "%Z%%M% %I% %E% SMI" 2 /* 3 * These routines check and fix parity of encryption keys for the DES 4 * algorithm. 5 * 6 * They are a replacement for routines in key_parity.c, that don't require 7 * the table building that they do. 8 * 9 * Mark Eichin -- Cygnus Support 10 */ 11 12 13 #include <des_int.h> 14 15 /* 16 * des_fixup_key_parity: Forces odd parity per byte; parity is bits 17 * 8,16,...64 in des order, implies 0, 8, 16, ... 18 * vax order. 19 */ 20 #define smask(step) ((1<<step)-1) 21 #define pstep(x,step) (((x)&smask(step))^(((x)>>step)&smask(step))) 22 #define parity_char(x) pstep(pstep(pstep((x),4),2),1) 23 24 void 25 mit_des_fixup_key_parity(key) 26 register mit_des_cblock key; 27 { 28 int i; 29 for (i=0; i<sizeof(mit_des_cblock); i++) 30 { 31 key[i] &= 0xfe; 32 key[i] |= 1^parity_char(key[i]); 33 } 34 35 return; 36 } 37 38 /* 39 * des_check_key_parity: returns true iff key has the correct des parity. 40 * See des_fix_key_parity for the definition of 41 * correct des parity. 42 */ 43 int 44 mit_des_check_key_parity(key) 45 register mit_des_cblock key; 46 { 47 int i; 48 49 for (i=0; i<sizeof(mit_des_cblock); i++) 50 { 51 if((key[i] & 1) == parity_char(0xfe&key[i])) 52 { 53 return 0; 54 } 55 } 56 57 return(1); 58 } 59 60