| 1 | #include "ssh.h" |
| 2 | |
| 3 | struct ssh_kex ssh_diffiehellman = { |
| 4 | "diffie-hellman-group1-sha1" |
| 5 | }; |
| 6 | |
| 7 | /* |
| 8 | * The prime p used in the key exchange. |
| 9 | */ |
| 10 | static unsigned short P[] = { |
| 11 | 64, |
| 12 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x5381, 0xECE6, 0x6651, 0x4928, |
| 13 | 0x1FE6, 0x7C4B, 0x2411, 0xAE9F, 0x9FA5, 0x5A89, 0x6BFB, 0xEE38, |
| 14 | 0xB7ED, 0xF406, 0x5CB6, 0x0BFF, 0xED6B, 0xA637, 0x42E9, 0xF44C, |
| 15 | 0x7EC6, 0x625E, 0xB576, 0xE485, 0xC245, 0x6D51, 0x356D, 0x4FE1, |
| 16 | 0x1437, 0xF25F, 0x0A6D, 0x302B, 0x431B, 0xCD3A, 0x19B3, 0xEF95, |
| 17 | 0x04DD, 0x8E34, 0x0879, 0x514A, 0x9B22, 0x3B13, 0xBEA6, 0x020B, |
| 18 | 0xCC74, 0x8A67, 0x4E08, 0x2902, 0x1CD1, 0x80DC, 0x628B, 0xC4C6, |
| 19 | 0xC234, 0x2168, 0xDAA2, 0xC90F, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, |
| 20 | }; |
| 21 | |
| 22 | /* |
| 23 | * The order q of the group: (p-1)/2. |
| 24 | */ |
| 25 | static unsigned short Q[] = { |
| 26 | 64, |
| 27 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x29C0, 0xF673, 0x3328, 0x2494, |
| 28 | 0x8FF3, 0xBE25, 0x9208, 0xD74F, 0xCFD2, 0xAD44, 0x35FD, 0xF71C, |
| 29 | 0x5BF6, 0x7A03, 0xAE5B, 0x85FF, 0xF6B5, 0xD31B, 0x2174, 0x7A26, |
| 30 | 0x3F63, 0x312F, 0xDABB, 0xF242, 0xE122, 0xB6A8, 0x9AB6, 0xA7F0, |
| 31 | 0x8A1B, 0xF92F, 0x8536, 0x9815, 0x218D, 0xE69D, 0x8CD9, 0xF7CA, |
| 32 | 0x026E, 0xC71A, 0x043C, 0x28A5, 0xCD91, 0x1D89, 0xDF53, 0x0105, |
| 33 | 0xE63A, 0x4533, 0x2704, 0x9481, 0x0E68, 0xC06E, 0x3145, 0x6263, |
| 34 | 0x611A, 0x10B4, 0xED51, 0xE487, 0xFFFF, 0xFFFF, 0xFFFF, 0x7FFF, |
| 35 | }; |
| 36 | |
| 37 | /* |
| 38 | * The bitmask covering q (for ease of generation of x). |
| 39 | */ |
| 40 | static unsigned short Qmask[] = { |
| 41 | 64, |
| 42 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, |
| 43 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, |
| 44 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, |
| 45 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, |
| 46 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, |
| 47 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, |
| 48 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, |
| 49 | 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x7FFF, |
| 50 | }; |
| 51 | |
| 52 | /* |
| 53 | * The generator g = 2. |
| 54 | */ |
| 55 | static unsigned short G[] = { 1, 2 }; |
| 56 | |
| 57 | /* |
| 58 | * Variables. |
| 59 | */ |
| 60 | static Bignum x, e; |
| 61 | |
| 62 | /* |
| 63 | * DH stage 1: invent a number x between 1 and q, and compute e = |
| 64 | * g^x mod p. Return e. |
| 65 | */ |
| 66 | Bignum dh_create_e(void) { |
| 67 | int i; |
| 68 | |
| 69 | x = newbn(Q[0]); |
| 70 | |
| 71 | tryagain: |
| 72 | |
| 73 | /* |
| 74 | * Create a potential x, by ANDing a string of random bytes |
| 75 | * with Qmask. |
| 76 | */ |
| 77 | for (i = 1; i <= x[0]; i++) |
| 78 | x[i] = ((random_byte() << 8) + random_byte()) & Qmask[i]; |
| 79 | |
| 80 | /* |
| 81 | * If x <= 1, go round again. |
| 82 | */ |
| 83 | for (i = 2; i <= x[0]; i++) |
| 84 | if (x[i] != 0) |
| 85 | break; |
| 86 | if (i > x[0] && x[1] <= 1) |
| 87 | goto tryagain; |
| 88 | |
| 89 | /* |
| 90 | * If x >= q, go round again. |
| 91 | */ |
| 92 | for (i = x[0]; i > 0; i--) { |
| 93 | if (x[i] > Q[i]) |
| 94 | goto tryagain; |
| 95 | if (x[i] < Q[i]) |
| 96 | break; |
| 97 | } |
| 98 | |
| 99 | /* |
| 100 | * Done. Now compute e = g^x mod p. |
| 101 | */ |
| 102 | e = newbn(P[0]); |
| 103 | modpow(G, x, P, e); |
| 104 | |
| 105 | return e; |
| 106 | } |
| 107 | |
| 108 | /* |
| 109 | * DH stage 2: given a number f, compute K = f^x mod p. |
| 110 | */ |
| 111 | Bignum dh_find_K(Bignum f) { |
| 112 | Bignum K = newbn(P[0]); |
| 113 | modpow(f, x, P, K); |
| 114 | return K; |
| 115 | } |