X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/putty/blobdiff_plain/59600f67b6dd739bb31a2cb23e887adef13c3ac8..e571c4d7ffa1cf60330ac0c7e3fb8b62533ff60e:/sshdss.c

diff --git a/sshdss.c b/sshdss.c
index 15b97ba1..d85d0007 100644
--- a/sshdss.c
+++ b/sshdss.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <assert.h>
 
 #include "ssh.h"
 
@@ -16,23 +17,6 @@
     (cp)[3] = (unsigned char)(value); }
 
 #if 0
-/*
- * Condition this section in for debugging of DSS.
- */
-static void diagbn(char *prefix, Bignum md) {
-    int i, nibbles, morenibbles;
-    static const char hex[] = "0123456789ABCDEF";
-
-    printf("%s0x", prefix ? prefix : "");
-
-    nibbles = (3 + ssh1_bignum_bitcount(md))/4; if (nibbles<1) nibbles=1;
-    morenibbles = 4*md[0] - nibbles;
-    for (i=0; i<morenibbles; i++) putchar('-');
-    for (i=nibbles; i-- ;)
-        putchar(hex[(bignum_byte(md, i/2) >> (4*(i%2))) & 0xF]);
-
-    if (prefix) putchar('\n');
-}
 #define DEBUG_DSS
 #else
 #define diagbn(x,y)
@@ -51,7 +35,7 @@ static void getstring(char **data, int *datalen, char **p, int *length) {
 }
 static Bignum getmp(char **data, int *datalen) {
     char *p;
-    int i, j, length;
+    int length;
     Bignum b;
 
     getstring(data, datalen, &p, &length);
@@ -59,45 +43,30 @@ static Bignum getmp(char **data, int *datalen) {
         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]);
-    }
-    while (b[0] > 1 && b[b[0]] == 0) b[0]--;
+    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
@@ -111,48 +80,64 @@ 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 * (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];
@@ -169,31 +154,33 @@ 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, "ssh-dss %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 slen;
     char hash[20];
     Bignum r, s, w, gu1p, yu2p, gu1yu2p, u1, u2, sha, v;
     int ret;
 
-    if (!dss_p)
+    if (!dss->p)
         return 0;
 
 #ifdef DEBUG_DSS
@@ -201,7 +188,7 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
         int i;
         printf("sig:");
         for (i=0;i<siglen;i++)
-            printf("  %02xf", (unsigned char)(sig[i]));
+            printf("  %02x", (unsigned char)(sig[i]));
         printf("\n");
     }
 #endif
@@ -218,15 +205,15 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
      */
     if (siglen != 40) {                /* bug not present; read admin fields */
         getstring(&sig, &siglen, &p, &slen);
-        if (!p || memcmp(p, "ssh-dss", 7)) {
+        if (!p || slen != 7 || memcmp(p, "ssh-dss", 7)) {
             return 0;
         }
         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);
@@ -237,7 +224,7 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
     /*
      * Step 1. w <- s^-1 mod q.
      */
-    w = modinv(s, dss_q);
+    w = modinv(s, dss->q);
     diagbn("w=", w);
 
     /*
@@ -246,25 +233,25 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
     SHA_Simple(data, datalen, hash);
     p = hash; slen = 20; sha = get160(&p, &slen);
     diagbn("sha=", sha);
-    u1 = modmul(sha, w, dss_q);
+    u1 = modmul(sha, w, dss->q);
     diagbn("u1=", u1);
 
     /*
      * Step 3. u2 <- r * w mod q.
      */
-    u2 = modmul(r, w, dss_q);
+    u2 = modmul(r, w, dss->q);
     diagbn("u2=", u2);
 
     /*
      * Step 4. v <- (g^u1 * y^u2 mod p) mod q.
      */
-    gu1p = modpow(dss_g, u1, dss_p);
+    gu1p = modpow(dss->g, u1, dss->p);
     diagbn("gu1p=", gu1p);
-    yu2p = modpow(dss_y, u2, dss_p);
+    yu2p = modpow(dss->y, u2, dss->p);
     diagbn("yu2p=", yu2p);
-    gu1yu2p = modmul(gu1p, yu2p, dss_p);
+    gu1yu2p = modmul(gu1p, yu2p, dss->p);
     diagbn("gu1yu2p=", gu1yu2p);
-    v = modmul(gu1yu2p, One, dss_q);
+    v = modmul(gu1yu2p, One, dss->q);
     diagbn("gu1yu2q=v=", v);
     diagbn("r=", r);
 
@@ -286,11 +273,67 @@ static int dss_verifysig(char *sig, int siglen, char *data, int datalen) {
     return ret;
 }
 
-struct ssh_hostkey ssh_dss = {
-    dss_setkey,
+static unsigned char *dss_public_blob(void *key, int *len) {
+    struct dss_key *dss = (struct dss_key *)key;
+    int plen, qlen, glen, ylen, bloblen;
+    int i;
+    unsigned char *blob, *p;
+
+    plen = (ssh1_bignum_bitcount(dss->p)+8)/8;
+    qlen = (ssh1_bignum_bitcount(dss->q)+8)/8;
+    glen = (ssh1_bignum_bitcount(dss->g)+8)/8;
+    ylen = (ssh1_bignum_bitcount(dss->y)+8)/8;
+
+    /*
+     * string "ssh-dss", mpint p, mpint q, mpint g, mpint y. Total
+     * 27 + sum of lengths. (five length fields, 20+7=27).
+     */
+    bloblen = 27+plen+qlen+glen+ylen;
+    blob = smalloc(bloblen);
+    p = blob;
+    PUT_32BIT(p, 7); p += 4;
+    memcpy(p, "ssh-dss", 7); p += 7;
+    PUT_32BIT(p, plen); p += 4;
+    for (i = plen; i-- ;) *p++ = bignum_byte(dss->p, i);
+    PUT_32BIT(p, qlen); p += 4;
+    for (i = qlen; i-- ;) *p++ = bignum_byte(dss->q, i);
+    PUT_32BIT(p, glen); p += 4;
+    for (i = glen; i-- ;) *p++ = bignum_byte(dss->g, i);
+    PUT_32BIT(p, ylen); p += 4;
+    for (i = ylen; i-- ;) *p++ = bignum_byte(dss->y, i);
+    assert(p == blob + bloblen);
+    *len = bloblen;
+    return blob;
+}
+
+static unsigned char *dss_private_blob(void *key, int *len) {
+    return NULL;		       /* can't handle DSS private keys */
+}
+
+static void *dss_createkey(unsigned char *pub_blob, int pub_len,
+			   unsigned char *priv_blob, int priv_len) {
+    return NULL;		       /* can't handle DSS private keys */
+}
+
+static void *dss_openssh_createkey(unsigned char **blob, int *len) {
+    return NULL;		       /* can't handle DSS private keys */
+}
+
+unsigned char *dss_sign(void *key, char *data, int datalen, int *siglen) {
+    return NULL;		       /* can't handle DSS private keys */
+}
+
+const struct ssh_signkey ssh_dss = {
+    dss_newkey,
+    dss_freekey,
     dss_fmtkey,
+    dss_public_blob,
+    dss_private_blob,
+    dss_createkey,
+    dss_openssh_createkey,
     dss_fingerprint,
     dss_verifysig,
+    dss_sign,
     "ssh-dss",
     "dss"
 };