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libsec: replace des based X9.17 genrandom() with chacha random number generator

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This commit is contained in:
cinap_lenrek 2016-12-28 02:02:00 +01:00
parent 84228515b6
commit ed9fdc72f5
2 changed files with 29 additions and 49 deletions
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9
sys/man/2/rand
View file

@ -31,8 +31,6 @@ ulong truerand(void)
.B
ulong ntruerand(ulong val)
.sp
.B #include <mp.h>
.br
.B #include <libsec.h>
.PP
.B
@ -117,10 +115,9 @@ returns a uniform random integer
.if n 0≤ x < val ≤ 2^32-1.
.PP
.I Genrandom
fills a buffer with bytes from the X9.17 pseudo-random
number generator. The X9.17 generator is seeded by 24
truly random bytes read from
.BR /dev/random .
fills a buffer with bytes from the cryptographic pseudo-random
number generator. The generator is automatically seeded by
.IR truerand .
.PP
.I Prng
uses the native

69
sys/src/libsec/port/genrandom.c
View file

@ -1,61 +1,44 @@
#include "os.h"
#include <libsec.h>
typedef struct State{
QLock lock;
int seeded;
uvlong seed;
DES3state des3;
} State;
static State x917state;
static void
X917(uchar *rand, int nrand)
init(Chachastate *cs)
{
int i, m, n8;
uvlong I, x;
ulong seed[11];
int i;
/* 1. Compute intermediate value I = Ek(time). */
I = nsec();
triple_block_cipher(x917state.des3.expanded, (uchar*)&I, 0); /* two-key EDE */
for(i=0; i<nelem(seed); i++)
seed[i] = truerand();
/* 2. x[i] = Ek(I^seed); seed = Ek(x[i]^I); */
m = (nrand+7)/8;
for(i=0; i<m; i++){
x = I ^ x917state.seed;
triple_block_cipher(x917state.des3.expanded, (uchar*)&x, 0);
n8 = (nrand>8) ? 8 : nrand;
memcpy(rand, (uchar*)&x, n8);
rand += 8;
nrand -= 8;
x ^= I;
triple_block_cipher(x917state.des3.expanded, (uchar*)&x, 0);
x917state.seed = x;
}
setupChachastate(cs, (uchar*)&seed[0], 32, (uchar*)&seed[8], 12, 20);
memset(seed, 0, sizeof(seed));
}
static void
X917init(void)
fill(Chachastate *cs, uchar *p, int n)
{
int n;
uchar mix[128];
uchar key3[3][8];
ulong *ulp;
Chachastate c;
ulp = (ulong*)key3;
for(n = 0; n < sizeof(key3)/sizeof(ulong); n++)
ulp[n] = truerand();
setupDES3state(&x917state.des3, key3, nil);
X917(mix, sizeof mix);
x917state.seeded = 1;
c = *cs;
chacha_encrypt((uchar*)&cs->input[4], 32, &c);
if(++cs->input[13] == 0)
if(++cs->input[14] == 0)
++cs->input[15];
chacha_encrypt(p, n, &c);
memset(&c, 0, sizeof(c));
}
void
genrandom(uchar *p, int n)
{
qlock(&x917state.lock);
if(x917state.seeded == 0)
X917init();
X917(p, n);
qunlock(&x917state.lock);
static QLock lk;
static Chachastate cs;
qlock(&lk);
if(cs.rounds == 0)
init(&cs);
cs.input[4] ^= getpid(); /* fork protection */
fill(&cs, p, n);
qunlock(&lk);
}