#include "ssh.h"
-struct ssh_kex ssh_diffiehellman = {
+const struct ssh_kex ssh_diffiehellman = {
"diffie-hellman-group1-sha1"
};
+const struct ssh_kex ssh_diffiehellman_gex = {
+ "diffie-hellman-group-exchange-sha1"
+};
+
/*
* 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;
/*
- * 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.
+ */
+void dh_setup_group1(void)
+{
+ p = bignum_from_bytes(P, sizeof(P));
+ g = bignum_from_bytes(G, sizeof(G));
+ dh_init();
+}
+
+/*
+ * Initialise DH for an alternative group.
*/
-static Bignum x, e;
+void dh_setup_group(Bignum pval, Bignum gval)
+{
+ p = copybn(pval);
+ g = copybn(gval);
+ 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 =
* g^x mod p. Return e.
+ *
+ * If `nbits' is greater than zero, it is used as an upper limit
+ * for the number of bits in x. This is safe provided that (a) you
+ * use twice as many bits in x as the number of bits you expect to
+ * use in your session key, and (b) the DH group is a safe prime
+ * (which SSH demands that it must be).
+ *
+ * P. C. van Oorschot, M. J. Wiener
+ * "On Diffie-Hellman Key Agreement with Short Exponents".
+ * Advances in Cryptology: Proceedings of Eurocrypt '96
+ * Springer-Verlag, May 1996.
*/
-Bignum dh_create_e(void) {
+Bignum dh_create_e(int nbits)
+{
int i;
- x = newbn(Q[0]);
+ int nbytes;
+ unsigned char *buf;
- tryagain:
+ nbytes = ssh1_bignum_length(qmask);
+ buf = smalloc(nbytes);
- /*
- * Create a potential x, by ANDing a string of random bytes
- * with Qmask.
- */
- for (i = 1; i <= x[0]; i++)
- x[i] = ((random_byte() << 8) + random_byte()) & Qmask[i];
-
- /*
- * If x <= 1, go round again.
- */
- for (i = 2; i <= x[0]; i++)
- if (x[i] != 0)
- break;
- if (i > x[0] && x[1] <= 1)
- goto tryagain;
-
- /*
- * If x >= q, go round again.
- */
- for (i = x[0]; i > 0; i--) {
- if (x[i] > Q[i])
- goto tryagain;
- if (x[i] < Q[i])
- break;
- }
+ do {
+ /*
+ * Create a potential x, by ANDing a string of random bytes
+ * with qmask.
+ */
+ if (x)
+ freebn(x);
+ if (nbits == 0 || nbits > bignum_bitcount(qmask)) {
+ ssh1_write_bignum(buf, qmask);
+ for (i = 2; i < nbytes; i++)
+ buf[i] &= random_byte();
+ ssh1_read_bignum(buf, &x);
+ } else {
+ int b, nb;
+ x = bn_power_2(nbits);
+ b = nb = 0;
+ for (i = 0; i < nbits; i++) {
+ if (nb == 0) {
+ nb = 8;
+ b = random_byte();
+ }
+ bignum_set_bit(x, i, b & 1);
+ b >>= 1;
+ nb--;
+ }
+ }
+ } 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;
}
/*
* DH stage 2: given a number f, compute K = f^x mod p.
*/
-Bignum dh_find_K(Bignum f) {
- Bignum K = newbn(P[0]);
- K = modpow(f, x, P);
- return K;
+Bignum dh_find_K(Bignum f)
+{
+ Bignum ret;
+ ret = modpow(f, x, p);
+ return ret;
}
projects / u / mdw / putty / blobdiff