X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/9c6214334f866ab91173df992180e168c17f904d..ded53fce5af6818acc2da88653b56c5c94377b8e:/sshdss.c?ds=sidebyside diff --git a/sshdss.c b/sshdss.c index 1bdaed5d..bacf68d4 100644 --- a/sshdss.c +++ b/sshdss.c @@ -16,7 +16,6 @@ (cp)[3] = (unsigned char)(value); } #if 0 -#define DEBUG_DSS /* * Condition this section in for debugging of DSS. */ @@ -34,6 +33,7 @@ static void diagbn(char *prefix, Bignum md) { if (prefix) putchar('\n'); } +#define DEBUG_DSS #else #define diagbn(x,y) #endif @@ -93,11 +93,17 @@ static Bignum get160(char **data, int *datalen) { 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 @@ -111,48 +117,61 @@ static void dss_setkey(char *data, int len) { #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 * (dss->p[0] + dss->q[0] + dss->g[0] + dss->y[0]); /* digits */ + 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]; @@ -169,31 +188,33 @@ static char *dss_fingerprint(void) { 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 @@ -223,10 +244,10 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) { } 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); + 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); @@ -237,46 +258,34 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) { /* * Step 1. w <- s^-1 mod q. */ - w = newbn(dss_q[0]); - 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); + 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); diagbn("sha=", sha); - modmul(sha, w, dss_q, u1); + 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); - diagbn("gu1p=", i1); - modpow(dss_y, u2, dss_p, i2); - diagbn("yu2p=", i2); - modmul(i1, i2, dss_p, i3); - diagbn("gu1yu2p=", 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); @@ -284,20 +293,13 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) { * 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); @@ -305,11 +307,18 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) { 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" };