((unsigned long)(unsigned char)(cp)[2] << 8) | \
((unsigned long)(unsigned char)(cp)[3]))
+#define PUT_32BIT(cp, value) { \
+ (cp)[0] = (unsigned char)((value) >> 24); \
+ (cp)[1] = (unsigned char)((value) >> 16); \
+ (cp)[2] = (unsigned char)((value) >> 8); \
+ (cp)[3] = (unsigned char)(value); }
+
static void getstring(char **data, int *datalen, char **p, int *length) {
*p = NULL;
if (*datalen < 4)
static char *dss_fmtkey(void) {
char *p;
- int len;
- int i;
+ int len, i, pos, nibbles;
+ static const char hex[] = "0123456789abcdef";
if (!dss_p)
return NULL;
- len = 7 + 4 + 1; /* "ssh-dss", punctuation, \0 */
+ 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);
if (!p) return NULL;
- strcpy(p, "ssh-dss:");
- for (i = dss_p[0]; i > 0; i--) sprintf(p+strlen(p), "%04X", dss_p[i]);
- strcat(p, "/");
- for (i = dss_q[0]; i > 0; i--) sprintf(p+strlen(p), "%04X", dss_q[i]);
- strcat(p, "/");
- for (i = dss_g[0]; i > 0; i--) sprintf(p+strlen(p), "%04X", dss_g[i]);
- strcat(p, "/");
- for (i = dss_y[0]; i > 0; i--) sprintf(p+strlen(p), "%04X", dss_y[i]);
+
+ pos = 0;
+ pos += sprintf(p+pos, "0x");
+ 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];
+ pos += sprintf(p+pos, ",0x");
+ 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];
+ pos += sprintf(p+pos, ",0x");
+ 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];
+ pos += sprintf(p+pos, ",0x");
+ 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] = '\0';
return p;
}
+static char *dss_fingerprint(void) {
+ struct MD5Context md5c;
+ unsigned char digest[16], lenbuf[4];
+ char buffer[16*3+40];
+ char *ret;
+ int numlen, i;
+
+ MD5Init(&md5c);
+ MD5Update(&md5c, "\0\0\0\7ssh-dss", 11);
+
+#define ADD_BIGNUM(bignum) \
+ numlen = (ssh1_bignum_bitcount(bignum)+8)/8; \
+ PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \
+ for (i = numlen; i-- ;) { \
+ 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);
+#undef ADD_BIGNUM
+
+ MD5Final(digest, &md5c);
+
+ 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);
+ if (ret)
+ strcpy(ret, buffer);
+ return ret;
+}
+
static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
char *p;
int i, slen;
if (!dss_p)
return 0;
- getstring(&sig, &siglen, &p, &slen);
- if (!p || memcmp(p, "ssh-dss", 7)) {
- return 0;
+ /*
+ * Commercial SSH (2.0.13) and OpenSSH disagree over the format
+ * of a DSA signature. OpenSSH is in line with the IETF drafts:
+ * it uses a string "ssh-dss", followed by a 40-byte string
+ * containing two 160-bit integers end-to-end. Commercial SSH
+ * can't be bothered with the header bit, and considers a DSA
+ * signature blob to be _just_ the 40-byte string containing
+ * the two 160-bit integers. We tell them apart by measuring
+ * the length: length 40 means the commercial-SSH bug, anything
+ * else is assumed to be IETF-compliant.
+ */
+ if (siglen != 40) { /* bug not present; read admin fields */
+ getstring(&sig, &siglen, &p, &slen);
+ if (!p || memcmp(p, "ssh-dss", 7)) {
+ return 0;
+ }
+ sig += 4, siglen -= 4; /* skip yet another length field */
}
- sig += 4, siglen -= 4; /* skip yet another length field */
r = get160(&sig, &siglen);
s = get160(&sig, &siglen);
if (!r || !s)
struct ssh_hostkey ssh_dss = {
dss_setkey,
dss_fmtkey,
+ dss_fingerprint,
dss_verifysig,
- "ssh-dss"
+ "ssh-dss",
+ "dss"
};