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1 | #include "ssh.h" |
2 | |
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3 | /* |
d1aaf71d |
4 | * The primes used in the group1 and group14 key exchange. |
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5 | */ |
d1aaf71d |
6 | static const unsigned char P1[] = { |
3709bfe9 |
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 |
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18 | }; |
d1aaf71d |
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 |
42 | }; |
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43 | |
44 | /* |
d1aaf71d |
45 | * The generator g = 2 (used for both group1 and group14). |
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46 | */ |
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47 | static const unsigned char G[] = { 2 }; |
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48 | |
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49 | static const struct ssh_kex ssh_diffiehellman_group1_sha1 = { |
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50 | "diffie-hellman-group1-sha1", "group1", |
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51 | P1, G, lenof(P1), lenof(G), &ssh_sha1 |
d1aaf71d |
52 | }; |
53 | |
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54 | static const struct ssh_kex *const group1_list[] = { |
55 | &ssh_diffiehellman_group1_sha1 |
56 | }; |
57 | |
58 | const struct ssh_kexes ssh_diffiehellman_group1 = { |
59 | sizeof(group1_list) / sizeof(*group1_list), |
60 | group1_list |
61 | }; |
62 | |
63 | static const struct ssh_kex ssh_diffiehellman_group14_sha1 = { |
d1aaf71d |
64 | "diffie-hellman-group14-sha1", "group14", |
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65 | P14, G, lenof(P14), lenof(G), &ssh_sha1 |
d1aaf71d |
66 | }; |
67 | |
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68 | static const struct ssh_kex *const group14_list[] = { |
69 | &ssh_diffiehellman_group14_sha1 |
70 | }; |
71 | |
72 | const struct ssh_kexes ssh_diffiehellman_group14 = { |
73 | sizeof(group14_list) / sizeof(*group14_list), |
74 | group14_list |
75 | }; |
76 | |
2ccb2fc8 |
77 | static const struct ssh_kex ssh_diffiehellman_gex_sha256 = { |
78 | "diffie-hellman-group-exchange-sha256", NULL, |
79 | NULL, NULL, 0, 0, &ssh_sha256 |
80 | }; |
81 | |
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82 | static const struct ssh_kex ssh_diffiehellman_gex_sha1 = { |
d1aaf71d |
83 | "diffie-hellman-group-exchange-sha1", NULL, |
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84 | NULL, NULL, 0, 0, &ssh_sha1 |
d1aaf71d |
85 | }; |
86 | |
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87 | static const struct ssh_kex *const gex_list[] = { |
2ccb2fc8 |
88 | &ssh_diffiehellman_gex_sha256, |
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89 | &ssh_diffiehellman_gex_sha1 |
90 | }; |
91 | |
92 | const struct ssh_kexes ssh_diffiehellman_gex = { |
93 | sizeof(gex_list) / sizeof(*gex_list), |
94 | gex_list |
95 | }; |
96 | |
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97 | /* |
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98 | * Variables. |
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99 | */ |
27cd7fc2 |
100 | struct dh_ctx { |
101 | Bignum x, e, p, q, qmask, g; |
102 | }; |
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103 | |
104 | /* |
3709bfe9 |
105 | * Common DH initialisation. |
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106 | */ |
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107 | static void dh_init(struct dh_ctx *ctx) |
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108 | { |
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109 | ctx->q = bignum_rshift(ctx->p, 1); |
110 | ctx->qmask = bignum_bitmask(ctx->q); |
111 | ctx->x = ctx->e = NULL; |
3709bfe9 |
112 | } |
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113 | |
114 | /* |
d1aaf71d |
115 | * Initialise DH for a standard group. |
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116 | */ |
d1aaf71d |
117 | void *dh_setup_group(const struct ssh_kex *kex) |
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118 | { |
3d88e64d |
119 | struct dh_ctx *ctx = snew(struct dh_ctx); |
d1aaf71d |
120 | ctx->p = bignum_from_bytes(kex->pdata, kex->plen); |
121 | ctx->g = bignum_from_bytes(kex->gdata, kex->glen); |
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122 | dh_init(ctx); |
123 | return ctx; |
3709bfe9 |
124 | } |
125 | |
126 | /* |
d1aaf71d |
127 | * Initialise DH for a server-supplied group. |
a92dd380 |
128 | */ |
d1aaf71d |
129 | void *dh_setup_gex(Bignum pval, Bignum gval) |
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130 | { |
3d88e64d |
131 | struct dh_ctx *ctx = snew(struct dh_ctx); |
27cd7fc2 |
132 | ctx->p = copybn(pval); |
133 | ctx->g = copybn(gval); |
134 | dh_init(ctx); |
135 | return ctx; |
a92dd380 |
136 | } |
137 | |
138 | /* |
27cd7fc2 |
139 | * Clean up and free a context. |
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140 | */ |
27cd7fc2 |
141 | void dh_cleanup(void *handle) |
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142 | { |
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143 | struct dh_ctx *ctx = (struct dh_ctx *)handle; |
144 | freebn(ctx->x); |
145 | freebn(ctx->e); |
146 | freebn(ctx->p); |
147 | freebn(ctx->g); |
148 | freebn(ctx->q); |
149 | freebn(ctx->qmask); |
150 | sfree(ctx); |
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151 | } |
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152 | |
153 | /* |
154 | * DH stage 1: invent a number x between 1 and q, and compute e = |
155 | * g^x mod p. Return e. |
7bd5a860 |
156 | * |
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). |
162 | * |
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. |
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167 | */ |
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168 | Bignum dh_create_e(void *handle, int nbits) |
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169 | { |
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170 | struct dh_ctx *ctx = (struct dh_ctx *)handle; |
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171 | int i; |
172 | |
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173 | int nbytes; |
174 | unsigned char *buf; |
175 | |
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176 | nbytes = ssh1_bignum_length(ctx->qmask); |
3d88e64d |
177 | buf = snewn(nbytes, unsigned char); |
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178 | |
a71540b9 |
179 | do { |
180 | /* |
181 | * Create a potential x, by ANDing a string of random bytes |
3709bfe9 |
182 | * with qmask. |
a71540b9 |
183 | */ |
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184 | if (ctx->x) |
185 | freebn(ctx->x); |
186 | if (nbits == 0 || nbits > bignum_bitcount(ctx->qmask)) { |
187 | ssh1_write_bignum(buf, ctx->qmask); |
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188 | for (i = 2; i < nbytes; i++) |
189 | buf[i] &= random_byte(); |
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190 | ssh1_read_bignum(buf, nbytes, &ctx->x); /* can't fail */ |
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191 | } else { |
192 | int b, nb; |
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193 | ctx->x = bn_power_2(nbits); |
2d466ffd |
194 | b = nb = 0; |
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195 | for (i = 0; i < nbits; i++) { |
196 | if (nb == 0) { |
197 | nb = 8; |
198 | b = random_byte(); |
199 | } |
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200 | bignum_set_bit(ctx->x, i, b & 1); |
7bd5a860 |
201 | b >>= 1; |
202 | nb--; |
203 | } |
204 | } |
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205 | } while (bignum_cmp(ctx->x, One) <= 0 || bignum_cmp(ctx->x, ctx->q) >= 0); |
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206 | |
170c1e6e |
207 | sfree(buf); |
208 | |
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209 | /* |
210 | * Done. Now compute e = g^x mod p. |
211 | */ |
27cd7fc2 |
212 | ctx->e = modpow(ctx->g, ctx->x, ctx->p); |
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213 | |
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214 | return ctx->e; |
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215 | } |
216 | |
217 | /* |
218 | * DH stage 2: given a number f, compute K = f^x mod p. |
219 | */ |
27cd7fc2 |
220 | Bignum dh_find_K(void *handle, Bignum f) |
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221 | { |
27cd7fc2 |
222 | struct dh_ctx *ctx = (struct dh_ctx *)handle; |
7bd5a860 |
223 | Bignum ret; |
27cd7fc2 |
224 | ret = modpow(f, ctx->x, ctx->p); |
7bd5a860 |
225 | return ret; |
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226 | } |