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Update DSS implementation to use new bignum routines

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[originally from svn r751]
This commit is contained in:
Simon Tatham 2000-10-23 16:03:21 +00:00
parent 36156d858c
commit bf2744aabf
1 changed files with 5 additions and 18 deletions
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23
sshdss.c
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@ -16,7 +16,6 @@
(cp)[3] = (unsigned char)(value); } (cp)[3] = (unsigned char)(value); }
#if 0 #if 0
#define DEBUG_DSS
/* /*
* Condition this section in for debugging of DSS. * Condition this section in for debugging of DSS.
*/ */
@ -34,6 +33,7 @@ static void diagbn(char *prefix, Bignum md) {
if (prefix) putchar('\n'); if (prefix) putchar('\n');
} }
#define DEBUG_DSS
#else #else
#define diagbn(x,y) #define diagbn(x,y)
#endif #endif
@ -188,9 +188,9 @@ static char *dss_fingerprint(void) {
static int dss_verifysig(char *sig, int siglen, char *data, int datalen) { static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
char *p; char *p;
int i, slen; int slen;
char hash[20]; char hash[20];
Bignum qm2, r, s, w, i1, i2, i3, u1, u2, sha, v; Bignum r, s, w, i1, i2, i3, u1, u2, sha, v;
int ret; int ret;
if (!dss_p) if (!dss_p)
@ -237,13 +237,7 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
/* /*
* Step 1. w <- s^-1 mod q. * Step 1. w <- s^-1 mod q.
*/ */
w = newbn(dss_q[0]); w = modinv(s, dss_q);
qm2 = copybn(dss_q);
decbn(qm2); decbn(qm2);
diagbn("qm2=", qm2);
/* Now qm2 is q-2, and by Fermat's Little Theorem, s^qm2 == s^-1 (mod q).
* This is a silly way to do it; may fix it later. */
modpow(s, qm2, dss_q, w);
diagbn("w=", w); diagbn("w=", w);
/* /*
@ -284,16 +278,9 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
* Step 5. v should now be equal to r. * Step 5. v should now be equal to r.
*/ */
ret = 1; ret = !bignum_cmp(v, r);
for (i = 1; i <= v[0] || i <= r[0]; i++) {
if ((i > v[0] && r[i] != 0) ||
(i > r[0] && v[i] != 0) ||
(i <= v[0] && i <= r[0] && r[i] != v[i]))
ret = 0;
}
freebn(w); freebn(w);
freebn(qm2);
freebn(sha); freebn(sha);
freebn(i1); freebn(i1);
freebn(i2); freebn(i2);