Remove the last lingering knowledge, outside sshbn.c, of the

internal structure of the Bignum type. Bignum is now a fully opaque
type unless you're inside sshbn.c.

[originally from svn r960]

1 files changed, 52 insertions, 45 deletions

diff --git a/sshdh.c b/sshdh.c
index dabed52a..35e66907 100644
--- a/sshdh.c
+++ b/sshdh.c
@@ -7,57 +7,57 @@ struct ssh_kex ssh_diffiehellman = {
 /*
  * The prime p used in the key exchange. 
  */
-static unsigned short P[] = {
-    64,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x5381, 0xECE6, 0x6651, 0x4928,
-    0x1FE6, 0x7C4B, 0x2411, 0xAE9F, 0x9FA5, 0x5A89, 0x6BFB, 0xEE38,
-    0xB7ED, 0xF406, 0x5CB6, 0x0BFF, 0xED6B, 0xA637, 0x42E9, 0xF44C,
-    0x7EC6, 0x625E, 0xB576, 0xE485, 0xC245, 0x6D51, 0x356D, 0x4FE1,
-    0x1437, 0xF25F, 0x0A6D, 0x302B, 0x431B, 0xCD3A, 0x19B3, 0xEF95,
-    0x04DD, 0x8E34, 0x0879, 0x514A, 0x9B22, 0x3B13, 0xBEA6, 0x020B,
-    0xCC74, 0x8A67, 0x4E08, 0x2902, 0x1CD1, 0x80DC, 0x628B, 0xC4C6,
-    0xC234, 0x2168, 0xDAA2, 0xC90F, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
+static unsigned char P[] = {
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
+    0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
+    0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
+    0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
+    0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
+    0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
+    0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
+    0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
+    0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
+    0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
 };
 
 /*
- * The order q of the group: (p-1)/2.
+ * The generator g = 2.
  */
-static unsigned short Q[] = {
-    64,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x29C0, 0xF673, 0x3328, 0x2494,
-    0x8FF3, 0xBE25, 0x9208, 0xD74F, 0xCFD2, 0xAD44, 0x35FD, 0xF71C,
-    0x5BF6, 0x7A03, 0xAE5B, 0x85FF, 0xF6B5, 0xD31B, 0x2174, 0x7A26,
-    0x3F63, 0x312F, 0xDABB, 0xF242, 0xE122, 0xB6A8, 0x9AB6, 0xA7F0,
-    0x8A1B, 0xF92F, 0x8536, 0x9815, 0x218D, 0xE69D, 0x8CD9, 0xF7CA,
-    0x026E, 0xC71A, 0x043C, 0x28A5, 0xCD91, 0x1D89, 0xDF53, 0x0105,
-    0xE63A, 0x4533, 0x2704, 0x9481, 0x0E68, 0xC06E, 0x3145, 0x6263,
-    0x611A, 0x10B4, 0xED51, 0xE487, 0xFFFF, 0xFFFF, 0xFFFF, 0x7FFF,
-};
+static unsigned char G[] = { 2 };
 
 /*
- * The bitmask covering q (for ease of generation of x).
+ * Variables.
  */
-static unsigned short Qmask[] = {
-    64,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x7FFF,
-};
+static Bignum x, e, p, q, qmask, g;
+static int need_to_free_pg;
 
 /*
- * The generator g = 2.
+ * Common DH initialisation.
  */
-static unsigned short G[] = { 1, 2 };
+static void dh_init(void) {
+    q = bignum_rshift(p, 1);
+    qmask = bignum_bitmask(q);
+}
 
 /*
- * Variables.
+ * Initialise DH for the standard group1.
  */
-static Bignum x, e;
+void dh_setup_group1(void) {
+    p = bignum_from_bytes(P, sizeof(P));
+    g = bignum_from_bytes(G, sizeof(G));
+    dh_init();
+}
+
+/*
+ * Clean up.
+ */
+void dh_cleanup(void) {
+    freebn(p);
+    freebn(g);
+    freebn(q);
+    freebn(qmask);
+}
 
 /*
  * DH stage 1: invent a number x between 1 and q, and compute e =
@@ -66,21 +66,28 @@ static Bignum x, e;
 Bignum dh_create_e(void) {
     int i;
 
-    x = newbn(Q[0]);
+    int nbytes;
+    unsigned char *buf;
+
+    nbytes = ssh1_bignum_length(qmask);
+    buf = smalloc(nbytes);
 
     do {
 	/*
 	 * Create a potential x, by ANDing a string of random bytes
-	 * with Qmask.
+	 * with qmask.
 	 */
-	for (i = 1; i <= x[0]; i++)
-	    x[i] = ((random_byte() << 8) + random_byte()) & Qmask[i];
-    } while (bignum_cmp(x, One) <= 0 || bignum_cmp(x, Q) >= 0);
+        if (x) freebn(x);
+        ssh1_write_bignum(buf, qmask);
+	for (i = 2; i < nbytes; i++)
+            buf[i] &= random_byte();
+        ssh1_read_bignum(buf, &x);
+    } while (bignum_cmp(x, One) <= 0 || bignum_cmp(x, q) >= 0);
 
     /*
      * Done. Now compute e = g^x mod p.
      */
-    e = modpow(G, x, P);
+    e = modpow(g, x, p);
 
     return e;
 }
@@ -89,5 +96,5 @@ Bignum dh_create_e(void) {
  * DH stage 2: given a number f, compute K = f^x mod p.
  */
 Bignum dh_find_K(Bignum f) {
-    return modpow(f, x, P);
+    return modpow(f, x, p);
 }