Add support for the OpenSSH SSH2 agent protocol.

[u/mdw/putty] / sshdss.c

diff --git a/sshdss.c b/sshdss.c
index bacf68d..d85d000 100644 (file)
--- 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);
@@ -59,37 +43,16 @@ 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;
 }
 
@@ -145,7 +108,10 @@ static char *dss_fmtkey(void *key) {
     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 */
+    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;
 
@@ -196,7 +162,7 @@ static char *dss_fingerprint(void *key) {
 
     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 = smalloc(strlen(buffer)+1);
@@ -222,7 +188,7 @@ static int dss_verifysig(void *key, char *sig, int siglen,
         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
@@ -239,7 +205,7 @@ static int dss_verifysig(void *key, char *sig, int siglen,
      */
     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 */
@@ -307,15 +273,64 @@ static int dss_verifysig(void *key, char *sig, int siglen,
     return ret;
 }
 
-int dss_sign(void *key, char *sig, int siglen,
-            char *data, int datalen) {
-    return 0;                         /* do nothing */
+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 */
 }
 
-struct ssh_signkey ssh_dss = {
+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,