1 #include "os.h"
2 #include <libsec.h>
3 
4 typedef struct State{
5 	QLock		lock;
6 	int		seeded;
7 	uvlong		seed;
8 	DES3state	des3;
9 } State;
10 static State x917state;
11 
12 static void
13 X917(uchar *rand, int nrand)
14 {
15 	int i, m, n8;
16 	uvlong I, x;
17 
18 	/* 1. Compute intermediate value I = Ek(time). */
19 	I = nsec();
20 	triple_block_cipher(x917state.des3.expanded, (uchar*)&I, 0); /* two-key EDE */
21 
22 	/* 2. x[i] = Ek(I^seed);  seed = Ek(x[i]^I); */
23 	m = (nrand+7)/8;
24 	for(i=0; i<m; i++){
25 		x = I ^ x917state.seed;
26 		triple_block_cipher(x917state.des3.expanded, (uchar*)&x, 0);
27 		n8 = (nrand>8) ? 8 : nrand;
28 		memcpy(rand, (uchar*)&x, n8);
29 		rand += 8;
30 		nrand -= 8;
31 		x ^= I;
32 		triple_block_cipher(x917state.des3.expanded, (uchar*)&x, 0);
33 		x917state.seed = x;
34 	}
35 }
36 
37 static void
38 X917init(void)
39 {
40 	int n;
41 	uchar mix[128];
42 	uchar key3[3][8];
43 	ulong *ulp;
44 
45 	ulp = (ulong*)key3;
46 	for(n = 0; n < sizeof(key3)/sizeof(ulong); n++)
47 		ulp[n] = truerand();
48 	setupDES3state(&x917state.des3, key3, nil);
49 	X917(mix, sizeof mix);
50 	x917state.seeded = 1;
51 }
52 
53 void
54 genrandom(uchar *p, int n)
55 {
56 	qlock(&x917state.lock);
57 	if(x917state.seeded == 0)
58 		X917init();
59 	X917(p, n);
60 	qunlock(&x917state.lock);
61 }