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Enhance Diffie-Hellman implementation to use bignum_cmp

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[originally from svn r762]
This commit is contained in:
Simon Tatham 2000-10-25 06:57:36 +00:00
parent 809bd81d5c
commit 38e7de3372
1 changed files with 9 additions and 30 deletions
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27
sshdh.c
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@ -68,33 +68,14 @@ Bignum dh_create_e(void) {
x = newbn(Q[0]); x = newbn(Q[0]);
tryagain: do {
/* /*
* Create a potential x, by ANDing a string of random bytes * Create a potential x, by ANDing a string of random bytes
* with Qmask. * with Qmask.
*/ */
for (i = 1; i <= x[0]; i++) for (i = 1; i <= x[0]; i++)
x[i] = ((random_byte() << 8) + random_byte()) & Qmask[i]; x[i] = ((random_byte() << 8) + random_byte()) & Qmask[i];
} while (bignum_cmp(x, One) <= 0 || bignum_cmp(x, Q) >= 0);
/*
* If x <= 1, go round again.
*/
for (i = 2; i <= x[0]; i++)
if (x[i] != 0)
break;
if (i > x[0] && x[1] <= 1)
goto tryagain;
/*
* If x >= q, go round again.
*/
for (i = x[0]; i > 0; i--) {
if (x[i] > Q[i])
goto tryagain;
if (x[i] < Q[i])
break;
}
/* /*
* Done. Now compute e = g^x mod p. * Done. Now compute e = g^x mod p.
@ -108,7 +89,5 @@ Bignum dh_create_e(void) {
* DH stage 2: given a number f, compute K = f^x mod p. * DH stage 2: given a number f, compute K = f^x mod p.
*/ */
Bignum dh_find_K(Bignum f) { Bignum dh_find_K(Bignum f) {
Bignum K = newbn(P[0]); return modpow(f, x, P);
K = modpow(f, x, P);
return K;
} }