(cp)[2] = (unsigned char)((value) >> 8); \
(cp)[3] = (unsigned char)(value); }
+#if 0
+#define DEBUG_DSS
+#else
+#define diagbn(x,y)
+#endif
+
static void getstring(char **data, int *datalen, char **p, int *length) {
*p = NULL;
if (*datalen < 4)
}
static Bignum getmp(char **data, int *datalen) {
char *p;
- int i, j, length;
+ int length;
Bignum b;
getstring(data, datalen, &p, &length);
return NULL;
if (p[0] & 0x80)
return NULL; /* negative mp */
- b = newbn((length+1)/2);
- for (i = 0; i < length; i++) {
- j = length - 1 - i;
- if (j & 1)
- b[j/2+1] |= ((unsigned char)p[i]) << 8;
- else
- b[j/2+1] |= ((unsigned char)p[i]);
- }
+ b = bignum_from_bytes(p, length);
return b;
}
static Bignum get160(char **data, int *datalen) {
- char *p;
- int i, j, length;
Bignum b;
- p = *data;
+ b = bignum_from_bytes(*data, 20);
*data += 20; *datalen -= 20;
- length = 20;
- while (length > 0 && !p[0])
- p++, length--;
- b = newbn((length+1)/2);
- for (i = 0; i < length; i++) {
- j = length - 1 - i;
- if (j & 1)
- b[j/2+1] |= ((unsigned char)p[i]) << 8;
- else
- b[j/2+1] |= ((unsigned char)p[i]);
- }
return b;
}
-static Bignum dss_p, dss_q, dss_g, dss_y;
+struct dss_key {
+ Bignum p, q, g, y;
+};
-static void dss_setkey(char *data, int len) {
+static void *dss_newkey(char *data, int len) {
char *p;
int slen;
+ struct dss_key *dss;
+
+ dss = smalloc(sizeof(struct dss_key));
+ if (!dss) return NULL;
getstring(&data, &len, &p, &slen);
+
+#ifdef DEBUG_DSS
+ {
+ int i;
+ printf("key:");
+ for (i=0;i<len;i++)
+ printf(" %02x", (unsigned char)(data[i]));
+ printf("\n");
+ }
+#endif
+
if (!p || memcmp(p, "ssh-dss", 7)) {
- dss_p = NULL;
- return;
+ sfree(dss);
+ return NULL;
}
- dss_p = getmp(&data, &len);
- dss_q = getmp(&data, &len);
- dss_g = getmp(&data, &len);
- dss_y = getmp(&data, &len);
+ dss->p = getmp(&data, &len);
+ dss->q = getmp(&data, &len);
+ dss->g = getmp(&data, &len);
+ dss->y = getmp(&data, &len);
+
+ return dss;
}
-static char *dss_fmtkey(void) {
+static void dss_freekey(void *key) {
+ struct dss_key *dss = (struct dss_key *)key;
+ freebn(dss->p);
+ freebn(dss->q);
+ freebn(dss->g);
+ freebn(dss->y);
+ sfree(dss);
+}
+
+static char *dss_fmtkey(void *key) {
+ struct dss_key *dss = (struct dss_key *)key;
char *p;
int len, i, pos, nibbles;
static const char hex[] = "0123456789abcdef";
- if (!dss_p)
+ if (!dss->p)
return NULL;
len = 8 + 4 + 1; /* 4 x "0x", punctuation, \0 */
- len += 4 * (dss_p[0] + dss_q[0] + dss_g[0] + dss_y[0]); /* digits */
- p = malloc(len);
+ len += 4 * (ssh1_bignum_bitcount(dss->p)+15)/16;
+ len += 4 * (ssh1_bignum_bitcount(dss->q)+15)/16;
+ len += 4 * (ssh1_bignum_bitcount(dss->g)+15)/16;
+ len += 4 * (ssh1_bignum_bitcount(dss->y)+15)/16;
+ p = smalloc(len);
if (!p) return NULL;
pos = 0;
pos += sprintf(p+pos, "0x");
- nibbles = (3 + ssh1_bignum_bitcount(dss_p))/4; if (nibbles<1) nibbles=1;
+ nibbles = (3 + ssh1_bignum_bitcount(dss->p))/4; if (nibbles<1) nibbles=1;
for (i=nibbles; i-- ;)
- p[pos++] = hex[(bignum_byte(dss_p, i/2) >> (4*(i%2))) & 0xF];
+ p[pos++] = hex[(bignum_byte(dss->p, i/2) >> (4*(i%2))) & 0xF];
pos += sprintf(p+pos, ",0x");
- nibbles = (3 + ssh1_bignum_bitcount(dss_q))/4; if (nibbles<1) nibbles=1;
+ nibbles = (3 + ssh1_bignum_bitcount(dss->q))/4; if (nibbles<1) nibbles=1;
for (i=nibbles; i-- ;)
- p[pos++] = hex[(bignum_byte(dss_q, i/2) >> (4*(i%2))) & 0xF];
+ p[pos++] = hex[(bignum_byte(dss->q, i/2) >> (4*(i%2))) & 0xF];
pos += sprintf(p+pos, ",0x");
- nibbles = (3 + ssh1_bignum_bitcount(dss_g))/4; if (nibbles<1) nibbles=1;
+ nibbles = (3 + ssh1_bignum_bitcount(dss->g))/4; if (nibbles<1) nibbles=1;
for (i=nibbles; i-- ;)
- p[pos++] = hex[(bignum_byte(dss_g, i/2) >> (4*(i%2))) & 0xF];
+ p[pos++] = hex[(bignum_byte(dss->g, i/2) >> (4*(i%2))) & 0xF];
pos += sprintf(p+pos, ",0x");
- nibbles = (3 + ssh1_bignum_bitcount(dss_y))/4; if (nibbles<1) nibbles=1;
+ nibbles = (3 + ssh1_bignum_bitcount(dss->y))/4; if (nibbles<1) nibbles=1;
for (i=nibbles; i-- ;)
- p[pos++] = hex[(bignum_byte(dss_y, i/2) >> (4*(i%2))) & 0xF];
+ p[pos++] = hex[(bignum_byte(dss->y, i/2) >> (4*(i%2))) & 0xF];
p[pos] = '\0';
return p;
}
-static char *dss_fingerprint(void) {
+static char *dss_fingerprint(void *key) {
+ struct dss_key *dss = (struct dss_key *)key;
struct MD5Context md5c;
unsigned char digest[16], lenbuf[4];
char buffer[16*3+40];
unsigned char c = bignum_byte(bignum, i); \
MD5Update(&md5c, &c, 1); \
}
- ADD_BIGNUM(dss_p);
- ADD_BIGNUM(dss_q);
- ADD_BIGNUM(dss_g);
- ADD_BIGNUM(dss_y);
+ ADD_BIGNUM(dss->p);
+ ADD_BIGNUM(dss->q);
+ ADD_BIGNUM(dss->g);
+ ADD_BIGNUM(dss->y);
#undef ADD_BIGNUM
MD5Final(digest, &md5c);
- sprintf(buffer, "%d ", ssh1_bignum_bitcount(dss_p));
+ sprintf(buffer, "%d ", ssh1_bignum_bitcount(dss->p));
for (i = 0; i < 16; i++)
sprintf(buffer+strlen(buffer), "%s%02x", i?":":"", digest[i]);
- ret = malloc(strlen(buffer)+1);
+ ret = smalloc(strlen(buffer)+1);
if (ret)
strcpy(ret, buffer);
return ret;
}
-static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
+static int dss_verifysig(void *key, char *sig, int siglen,
+ char *data, int datalen) {
+ struct dss_key *dss = (struct dss_key *)key;
char *p;
- int i, slen;
+ int slen;
char hash[20];
- Bignum qm2, r, s, w, i1, i2, i3, u1, u2, sha, v;
+ Bignum r, s, w, gu1p, yu2p, gu1yu2p, u1, u2, sha, v;
int ret;
- if (!dss_p)
+ if (!dss->p)
return 0;
+#ifdef DEBUG_DSS
+ {
+ int i;
+ printf("sig:");
+ for (i=0;i<siglen;i++)
+ printf(" %02x", (unsigned char)(sig[i]));
+ printf("\n");
+ }
+#endif
/*
* Commercial SSH (2.0.13) and OpenSSH disagree over the format
* of a DSA signature. OpenSSH is in line with the IETF drafts:
}
sig += 4, siglen -= 4; /* skip yet another length field */
}
+ diagbn("p=", dss->p);
+ diagbn("q=", dss->q);
+ diagbn("g=", dss->g);
+ diagbn("y=", dss->y);
r = get160(&sig, &siglen);
+ diagbn("r=", r);
s = get160(&sig, &siglen);
+ diagbn("s=", s);
if (!r || !s)
return 0;
/*
* Step 1. w <- s^-1 mod q.
*/
- w = newbn(dss_q[0]);
- qm2 = copybn(dss_q);
- decbn(qm2); decbn(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);
+ w = modinv(s, dss->q);
+ diagbn("w=", w);
/*
* Step 2. u1 <- SHA(message) * w mod q.
*/
- u1 = newbn(dss_q[0]);
SHA_Simple(data, datalen, hash);
p = hash; slen = 20; sha = get160(&p, &slen);
- modmul(sha, w, dss_q, u1);
+ diagbn("sha=", sha);
+ u1 = modmul(sha, w, dss->q);
+ diagbn("u1=", u1);
/*
* Step 3. u2 <- r * w mod q.
*/
- u2 = newbn(dss_q[0]);
- modmul(r, w, dss_q, u2);
+ u2 = modmul(r, w, dss->q);
+ diagbn("u2=", u2);
/*
* Step 4. v <- (g^u1 * y^u2 mod p) mod q.
*/
- i1 = newbn(dss_p[0]);
- i2 = newbn(dss_p[0]);
- i3 = newbn(dss_p[0]);
- v = newbn(dss_q[0]);
- modpow(dss_g, u1, dss_p, i1);
- modpow(dss_y, u2, dss_p, i2);
- modmul(i1, i2, dss_p, i3);
- modmul(i3, One, dss_q, v);
+ gu1p = modpow(dss->g, u1, dss->p);
+ diagbn("gu1p=", gu1p);
+ yu2p = modpow(dss->y, u2, dss->p);
+ diagbn("yu2p=", yu2p);
+ gu1yu2p = modmul(gu1p, yu2p, dss->p);
+ diagbn("gu1yu2p=", gu1yu2p);
+ v = modmul(gu1yu2p, One, dss->q);
+ diagbn("gu1yu2q=v=", v);
+ diagbn("r=", r);
/*
* Step 5. v should now be equal to r.
*/
- ret = 1;
- 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;
- }
+ ret = !bignum_cmp(v, r);
freebn(w);
- freebn(qm2);
freebn(sha);
- freebn(i1);
- freebn(i2);
- freebn(i3);
+ freebn(gu1p);
+ freebn(yu2p);
+ freebn(gu1yu2p);
freebn(v);
freebn(r);
freebn(s);
return ret;
}
-struct ssh_hostkey ssh_dss = {
- dss_setkey,
+int dss_sign(void *key, char *sig, int siglen,
+ char *data, int datalen) {
+ return 0; /* do nothing */
+}
+
+struct ssh_signkey ssh_dss = {
+ dss_newkey,
+ dss_freekey,
dss_fmtkey,
dss_fingerprint,
dss_verifysig,
+ dss_sign,
"ssh-dss",
"dss"
};
projects / u / mdw / putty / blobdiff