Commit | Line | Data |
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2fe58dfd SE |
1 | #include <stdio.h> |
2 | #include <gmp.h> | |
3 | ||
4 | #include "secnet.h" | |
5 | #include "util.h" | |
6 | ||
7 | struct dh { | |
8 | closure_t cl; | |
9 | struct dh_if ops; | |
10 | struct cloc loc; | |
11 | MP_INT p,g; /* prime modulus and generator */ | |
12 | }; | |
13 | ||
14 | static string_t dh_makepublic(void *sst, uint8_t *secret, uint32_t secretlen) | |
15 | { | |
16 | struct dh *st=sst; | |
17 | string_t r; | |
18 | MP_INT a, b; /* a is secret key, b is public key */ | |
19 | ||
20 | mpz_init(&a); | |
21 | mpz_init(&b); | |
22 | ||
23 | read_mpbin(&a, secret, secretlen); | |
24 | ||
25 | mpz_powm(&b, &st->g, &a, &st->p); | |
26 | ||
27 | r=write_mpstring(&b); | |
28 | ||
29 | mpz_clear(&a); | |
30 | mpz_clear(&b); | |
31 | return r; | |
32 | } | |
33 | ||
fe5e9cc4 | 34 | static dh_makeshared_fn dh_makeshared; |
2fe58dfd | 35 | static void dh_makeshared(void *sst, uint8_t *secret, uint32_t secretlen, |
fe5e9cc4 | 36 | cstring_t rempublic, uint8_t *sharedsecret, |
2fe58dfd SE |
37 | uint32_t buflen) |
38 | { | |
39 | struct dh *st=sst; | |
40 | MP_INT a, b, c; | |
41 | ||
42 | mpz_init(&a); | |
43 | mpz_init(&b); | |
44 | mpz_init(&c); | |
45 | ||
46 | read_mpbin(&a, secret, secretlen); | |
47 | mpz_set_str(&b, rempublic, 16); | |
48 | ||
49 | mpz_powm(&c, &b, &a, &st->p); | |
50 | ||
51 | write_mpbin(&c,sharedsecret,buflen); | |
52 | ||
53 | mpz_clear(&a); | |
54 | mpz_clear(&b); | |
55 | mpz_clear(&c); | |
56 | } | |
57 | ||
58 | static list_t *dh_apply(closure_t *self, struct cloc loc, dict_t *context, | |
59 | list_t *args) | |
60 | { | |
61 | struct dh *st; | |
62 | string_t p,g; | |
63 | item_t *i; | |
64 | ||
65 | st=safe_malloc(sizeof(*st),"dh_apply"); | |
66 | st->cl.description="dh"; | |
67 | st->cl.type=CL_DH; | |
68 | st->cl.apply=NULL; | |
69 | st->cl.interface=&st->ops; | |
70 | st->ops.st=st; | |
71 | st->ops.makepublic=dh_makepublic; | |
72 | st->ops.makeshared=dh_makeshared; | |
73 | st->loc=loc; | |
74 | /* We have two string arguments: the first is the modulus, and the | |
75 | second is the generator. Both are in hex. */ | |
76 | i=list_elem(args,0); | |
77 | if (i) { | |
78 | if (i->type!=t_string) { | |
79 | cfgfatal(i->loc,"diffie-hellman","first argument must be a " | |
80 | "string\n"); | |
81 | } | |
82 | p=i->data.string; | |
83 | if (mpz_init_set_str(&st->p,p,16)!=0) { | |
84 | cfgfatal(i->loc,"diffie-hellman","\"%s\" is not a hex number " | |
85 | "string\n",p); | |
86 | } | |
87 | } else { | |
88 | cfgfatal(loc,"diffie-hellman","you must provide a prime modulus\n"); | |
89 | } | |
90 | ||
91 | i=list_elem(args,1); | |
92 | if (i) { | |
93 | if (i->type!=t_string) { | |
94 | cfgfatal(i->loc,"diffie-hellman","second argument must be a " | |
95 | "string\n"); | |
96 | } | |
97 | g=i->data.string; | |
98 | if (mpz_init_set_str(&st->g,g,16)!=0) { | |
99 | cfgfatal(i->loc,"diffie-hellman","\"%s\" is not a hex number " | |
100 | "string\n",g); | |
101 | } | |
102 | } else { | |
103 | cfgfatal(loc,"diffie-hellman","you must provide a generator\n"); | |
104 | } | |
105 | ||
70dc107b SE |
106 | i=list_elem(args,2); |
107 | if (i && i->type==t_bool && i->data.bool==False) { | |
108 | Message(M_INFO,"diffie-hellman (%s:%d): skipping modulus " | |
109 | "primality check\n",loc.file,loc.line); | |
110 | } else { | |
111 | /* Test that the modulus is really prime */ | |
112 | if (mpz_probab_prime_p(&st->p,5)==0) { | |
113 | cfgfatal(loc,"diffie-hellman","modulus must be a prime\n"); | |
114 | } | |
2fe58dfd SE |
115 | } |
116 | st->ops.len=mpz_sizeinbase(&st->p,2)/8; | |
117 | ||
118 | return new_closure(&st->cl); | |
119 | } | |
120 | ||
121 | init_module dh_module; | |
122 | void dh_module(dict_t *dict) | |
123 | { | |
124 | add_closure(dict,"diffie-hellman",dh_apply); | |
125 | } |