4 * The primes used in the group1 and group14 key exchange.
6 static const unsigned char P1[] = {
7 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
8 0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
9 0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
10 0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
11 0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
12 0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
13 0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
14 0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
15 0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
16 0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
17 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
19 static const unsigned char P14[] = {
20 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
21 0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
22 0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
23 0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
24 0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
25 0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
26 0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
27 0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
28 0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
29 0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
30 0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
31 0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
32 0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
33 0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
34 0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
35 0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
36 0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
37 0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
38 0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
39 0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
40 0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAC, 0xAA, 0x68, 0xFF, 0xFF, 0xFF, 0xFF,
41 0xFF, 0xFF, 0xFF, 0xFF
45 * The generator g = 2 (used for both group1 and group14).
47 static const unsigned char G[] = { 2 };
49 static const struct ssh_kex ssh_diffiehellman_group1_sha1 = {
50 "diffie-hellman-group1-sha1", "group1",
51 P1, G, lenof(P1), lenof(G), &ssh_sha1
54 static const struct ssh_kex *const group1_list[] = {
55 &ssh_diffiehellman_group1_sha1
58 const struct ssh_kexes ssh_diffiehellman_group1 = {
59 sizeof(group1_list) / sizeof(*group1_list),
63 static const struct ssh_kex ssh_diffiehellman_group14_sha1 = {
64 "diffie-hellman-group14-sha1", "group14",
65 P14, G, lenof(P14), lenof(G), &ssh_sha1
68 static const struct ssh_kex *const group14_list[] = {
69 &ssh_diffiehellman_group14_sha1
72 const struct ssh_kexes ssh_diffiehellman_group14 = {
73 sizeof(group14_list) / sizeof(*group14_list),
77 static const struct ssh_kex ssh_diffiehellman_gex_sha256 = {
78 "diffie-hellman-group-exchange-sha256", NULL,
79 NULL, NULL, 0, 0, &ssh_sha256
82 static const struct ssh_kex ssh_diffiehellman_gex_sha1 = {
83 "diffie-hellman-group-exchange-sha1", NULL,
84 NULL, NULL, 0, 0, &ssh_sha1
87 static const struct ssh_kex *const gex_list[] = {
88 &ssh_diffiehellman_gex_sha256,
89 &ssh_diffiehellman_gex_sha1
92 const struct ssh_kexes ssh_diffiehellman_gex = {
93 sizeof(gex_list) / sizeof(*gex_list),
101 Bignum x, e, p, q, qmask, g;
105 * Common DH initialisation.
107 static void dh_init(struct dh_ctx *ctx)
109 ctx->q = bignum_rshift(ctx->p, 1);
110 ctx->qmask = bignum_bitmask(ctx->q);
111 ctx->x = ctx->e = NULL;
115 * Initialise DH for a standard group.
117 void *dh_setup_group(const struct ssh_kex *kex)
119 struct dh_ctx *ctx = snew(struct dh_ctx);
120 ctx->p = bignum_from_bytes(kex->pdata, kex->plen);
121 ctx->g = bignum_from_bytes(kex->gdata, kex->glen);
127 * Initialise DH for a server-supplied group.
129 void *dh_setup_gex(Bignum pval, Bignum gval)
131 struct dh_ctx *ctx = snew(struct dh_ctx);
132 ctx->p = copybn(pval);
133 ctx->g = copybn(gval);
139 * Clean up and free a context.
141 void dh_cleanup(void *handle)
143 struct dh_ctx *ctx = (struct dh_ctx *)handle;
154 * DH stage 1: invent a number x between 1 and q, and compute e =
155 * g^x mod p. Return e.
157 * If `nbits' is greater than zero, it is used as an upper limit
158 * for the number of bits in x. This is safe provided that (a) you
159 * use twice as many bits in x as the number of bits you expect to
160 * use in your session key, and (b) the DH group is a safe prime
161 * (which SSH demands that it must be).
163 * P. C. van Oorschot, M. J. Wiener
164 * "On Diffie-Hellman Key Agreement with Short Exponents".
165 * Advances in Cryptology: Proceedings of Eurocrypt '96
166 * Springer-Verlag, May 1996.
168 Bignum dh_create_e(void *handle, int nbits)
170 struct dh_ctx *ctx = (struct dh_ctx *)handle;
176 nbytes = ssh1_bignum_length(ctx->qmask);
177 buf = snewn(nbytes, unsigned char);
181 * Create a potential x, by ANDing a string of random bytes
186 if (nbits == 0 || nbits > bignum_bitcount(ctx->qmask)) {
187 ssh1_write_bignum(buf, ctx->qmask);
188 for (i = 2; i < nbytes; i++)
189 buf[i] &= random_byte();
190 ssh1_read_bignum(buf, nbytes, &ctx->x); /* can't fail */
193 ctx->x = bn_power_2(nbits);
195 for (i = 0; i < nbits; i++) {
200 bignum_set_bit(ctx->x, i, b & 1);
205 } while (bignum_cmp(ctx->x, One) <= 0 || bignum_cmp(ctx->x, ctx->q) >= 0);
210 * Done. Now compute e = g^x mod p.
212 ctx->e = modpow(ctx->g, ctx->x, ctx->p);
218 * DH stage 2: given a number f, compute K = f^x mod p.
220 Bignum dh_find_K(void *handle, Bignum f)
222 struct dh_ctx *ctx = (struct dh_ctx *)handle;
224 ret = modpow(f, ctx->x, ctx->p);