#include "ssh.h" struct ssh_kex ssh_diffiehellman = { "diffie-hellman-group1-sha1" }; struct ssh_kex ssh_diffiehellman_gex = { "diffie-hellman-group-exchange-sha1" }; /* * The prime p used in the key exchange. */ 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 generator g = 2. */ static unsigned char G[] = { 2 }; /* * Variables. */ static Bignum x, e, p, q, qmask, g; static int need_to_free_pg; /* * Common DH initialisation. */ static void dh_init(void) { q = bignum_rshift(p, 1); qmask = bignum_bitmask(q); } /* * 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. */ 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. */ Bignum dh_create_e(void) { int i; 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. */ 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); return e; } /* * DH stage 2: given a number f, compute K = f^x mod p. */ Bignum dh_find_K(Bignum f) { return modpow(f, x, p); }