1*0957b409SSimon J. Gerraty /*
2*0957b409SSimon J. Gerraty * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3*0957b409SSimon J. Gerraty *
4*0957b409SSimon J. Gerraty * Permission is hereby granted, free of charge, to any person obtaining
5*0957b409SSimon J. Gerraty * a copy of this software and associated documentation files (the
6*0957b409SSimon J. Gerraty * "Software"), to deal in the Software without restriction, including
7*0957b409SSimon J. Gerraty * without limitation the rights to use, copy, modify, merge, publish,
8*0957b409SSimon J. Gerraty * distribute, sublicense, and/or sell copies of the Software, and to
9*0957b409SSimon J. Gerraty * permit persons to whom the Software is furnished to do so, subject to
10*0957b409SSimon J. Gerraty * the following conditions:
11*0957b409SSimon J. Gerraty *
12*0957b409SSimon J. Gerraty * The above copyright notice and this permission notice shall be
13*0957b409SSimon J. Gerraty * included in all copies or substantial portions of the Software.
14*0957b409SSimon J. Gerraty *
15*0957b409SSimon J. Gerraty * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16*0957b409SSimon J. Gerraty * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17*0957b409SSimon J. Gerraty * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18*0957b409SSimon J. Gerraty * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19*0957b409SSimon J. Gerraty * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20*0957b409SSimon J. Gerraty * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21*0957b409SSimon J. Gerraty * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22*0957b409SSimon J. Gerraty * SOFTWARE.
23*0957b409SSimon J. Gerraty */
24*0957b409SSimon J. Gerraty
25*0957b409SSimon J. Gerraty #include "inner.h"
26*0957b409SSimon J. Gerraty
27*0957b409SSimon J. Gerraty /* see bearssl.h */
28*0957b409SSimon J. Gerraty void
br_hmac_drbg_init(br_hmac_drbg_context * ctx,const br_hash_class * digest_class,const void * seed,size_t len)29*0957b409SSimon J. Gerraty br_hmac_drbg_init(br_hmac_drbg_context *ctx,
30*0957b409SSimon J. Gerraty const br_hash_class *digest_class, const void *seed, size_t len)
31*0957b409SSimon J. Gerraty {
32*0957b409SSimon J. Gerraty size_t hlen;
33*0957b409SSimon J. Gerraty
34*0957b409SSimon J. Gerraty ctx->vtable = &br_hmac_drbg_vtable;
35*0957b409SSimon J. Gerraty hlen = br_digest_size(digest_class);
36*0957b409SSimon J. Gerraty memset(ctx->K, 0x00, hlen);
37*0957b409SSimon J. Gerraty memset(ctx->V, 0x01, hlen);
38*0957b409SSimon J. Gerraty ctx->digest_class = digest_class;
39*0957b409SSimon J. Gerraty br_hmac_drbg_update(ctx, seed, len);
40*0957b409SSimon J. Gerraty }
41*0957b409SSimon J. Gerraty
42*0957b409SSimon J. Gerraty /* see bearssl.h */
43*0957b409SSimon J. Gerraty void
br_hmac_drbg_generate(br_hmac_drbg_context * ctx,void * out,size_t len)44*0957b409SSimon J. Gerraty br_hmac_drbg_generate(br_hmac_drbg_context *ctx, void *out, size_t len)
45*0957b409SSimon J. Gerraty {
46*0957b409SSimon J. Gerraty const br_hash_class *dig;
47*0957b409SSimon J. Gerraty br_hmac_key_context kc;
48*0957b409SSimon J. Gerraty br_hmac_context hc;
49*0957b409SSimon J. Gerraty size_t hlen;
50*0957b409SSimon J. Gerraty unsigned char *buf;
51*0957b409SSimon J. Gerraty unsigned char x;
52*0957b409SSimon J. Gerraty
53*0957b409SSimon J. Gerraty dig = ctx->digest_class;
54*0957b409SSimon J. Gerraty hlen = br_digest_size(dig);
55*0957b409SSimon J. Gerraty br_hmac_key_init(&kc, dig, ctx->K, hlen);
56*0957b409SSimon J. Gerraty buf = out;
57*0957b409SSimon J. Gerraty while (len > 0) {
58*0957b409SSimon J. Gerraty size_t clen;
59*0957b409SSimon J. Gerraty
60*0957b409SSimon J. Gerraty br_hmac_init(&hc, &kc, 0);
61*0957b409SSimon J. Gerraty br_hmac_update(&hc, ctx->V, hlen);
62*0957b409SSimon J. Gerraty br_hmac_out(&hc, ctx->V);
63*0957b409SSimon J. Gerraty clen = hlen;
64*0957b409SSimon J. Gerraty if (clen > len) {
65*0957b409SSimon J. Gerraty clen = len;
66*0957b409SSimon J. Gerraty }
67*0957b409SSimon J. Gerraty memcpy(buf, ctx->V, clen);
68*0957b409SSimon J. Gerraty buf += clen;
69*0957b409SSimon J. Gerraty len -= clen;
70*0957b409SSimon J. Gerraty }
71*0957b409SSimon J. Gerraty
72*0957b409SSimon J. Gerraty /*
73*0957b409SSimon J. Gerraty * To prepare the state for the next request, we should call
74*0957b409SSimon J. Gerraty * br_hmac_drbg_update() with an empty additional seed. However,
75*0957b409SSimon J. Gerraty * we already have an initialized HMAC context with the right
76*0957b409SSimon J. Gerraty * initial key, and we don't want to push another one on the
77*0957b409SSimon J. Gerraty * stack, so we inline that update() call here.
78*0957b409SSimon J. Gerraty */
79*0957b409SSimon J. Gerraty br_hmac_init(&hc, &kc, 0);
80*0957b409SSimon J. Gerraty br_hmac_update(&hc, ctx->V, hlen);
81*0957b409SSimon J. Gerraty x = 0x00;
82*0957b409SSimon J. Gerraty br_hmac_update(&hc, &x, 1);
83*0957b409SSimon J. Gerraty br_hmac_out(&hc, ctx->K);
84*0957b409SSimon J. Gerraty br_hmac_key_init(&kc, dig, ctx->K, hlen);
85*0957b409SSimon J. Gerraty br_hmac_init(&hc, &kc, 0);
86*0957b409SSimon J. Gerraty br_hmac_update(&hc, ctx->V, hlen);
87*0957b409SSimon J. Gerraty br_hmac_out(&hc, ctx->V);
88*0957b409SSimon J. Gerraty }
89*0957b409SSimon J. Gerraty
90*0957b409SSimon J. Gerraty /* see bearssl.h */
91*0957b409SSimon J. Gerraty void
br_hmac_drbg_update(br_hmac_drbg_context * ctx,const void * seed,size_t len)92*0957b409SSimon J. Gerraty br_hmac_drbg_update(br_hmac_drbg_context *ctx, const void *seed, size_t len)
93*0957b409SSimon J. Gerraty {
94*0957b409SSimon J. Gerraty const br_hash_class *dig;
95*0957b409SSimon J. Gerraty br_hmac_key_context kc;
96*0957b409SSimon J. Gerraty br_hmac_context hc;
97*0957b409SSimon J. Gerraty size_t hlen;
98*0957b409SSimon J. Gerraty unsigned char x;
99*0957b409SSimon J. Gerraty
100*0957b409SSimon J. Gerraty dig = ctx->digest_class;
101*0957b409SSimon J. Gerraty hlen = br_digest_size(dig);
102*0957b409SSimon J. Gerraty
103*0957b409SSimon J. Gerraty /*
104*0957b409SSimon J. Gerraty * 1. K = HMAC(K, V || 0x00 || seed)
105*0957b409SSimon J. Gerraty */
106*0957b409SSimon J. Gerraty br_hmac_key_init(&kc, dig, ctx->K, hlen);
107*0957b409SSimon J. Gerraty br_hmac_init(&hc, &kc, 0);
108*0957b409SSimon J. Gerraty br_hmac_update(&hc, ctx->V, hlen);
109*0957b409SSimon J. Gerraty x = 0x00;
110*0957b409SSimon J. Gerraty br_hmac_update(&hc, &x, 1);
111*0957b409SSimon J. Gerraty br_hmac_update(&hc, seed, len);
112*0957b409SSimon J. Gerraty br_hmac_out(&hc, ctx->K);
113*0957b409SSimon J. Gerraty br_hmac_key_init(&kc, dig, ctx->K, hlen);
114*0957b409SSimon J. Gerraty
115*0957b409SSimon J. Gerraty /*
116*0957b409SSimon J. Gerraty * 2. V = HMAC(K, V)
117*0957b409SSimon J. Gerraty */
118*0957b409SSimon J. Gerraty br_hmac_init(&hc, &kc, 0);
119*0957b409SSimon J. Gerraty br_hmac_update(&hc, ctx->V, hlen);
120*0957b409SSimon J. Gerraty br_hmac_out(&hc, ctx->V);
121*0957b409SSimon J. Gerraty
122*0957b409SSimon J. Gerraty /*
123*0957b409SSimon J. Gerraty * 3. If the additional seed is empty, then stop here.
124*0957b409SSimon J. Gerraty */
125*0957b409SSimon J. Gerraty if (len == 0) {
126*0957b409SSimon J. Gerraty return;
127*0957b409SSimon J. Gerraty }
128*0957b409SSimon J. Gerraty
129*0957b409SSimon J. Gerraty /*
130*0957b409SSimon J. Gerraty * 4. K = HMAC(K, V || 0x01 || seed)
131*0957b409SSimon J. Gerraty */
132*0957b409SSimon J. Gerraty br_hmac_init(&hc, &kc, 0);
133*0957b409SSimon J. Gerraty br_hmac_update(&hc, ctx->V, hlen);
134*0957b409SSimon J. Gerraty x = 0x01;
135*0957b409SSimon J. Gerraty br_hmac_update(&hc, &x, 1);
136*0957b409SSimon J. Gerraty br_hmac_update(&hc, seed, len);
137*0957b409SSimon J. Gerraty br_hmac_out(&hc, ctx->K);
138*0957b409SSimon J. Gerraty br_hmac_key_init(&kc, dig, ctx->K, hlen);
139*0957b409SSimon J. Gerraty
140*0957b409SSimon J. Gerraty /*
141*0957b409SSimon J. Gerraty * 5. V = HMAC(K, V)
142*0957b409SSimon J. Gerraty */
143*0957b409SSimon J. Gerraty br_hmac_init(&hc, &kc, 0);
144*0957b409SSimon J. Gerraty br_hmac_update(&hc, ctx->V, hlen);
145*0957b409SSimon J. Gerraty br_hmac_out(&hc, ctx->V);
146*0957b409SSimon J. Gerraty }
147*0957b409SSimon J. Gerraty
148*0957b409SSimon J. Gerraty /* see bearssl.h */
149*0957b409SSimon J. Gerraty const br_prng_class br_hmac_drbg_vtable = {
150*0957b409SSimon J. Gerraty sizeof(br_hmac_drbg_context),
151*0957b409SSimon J. Gerraty (void (*)(const br_prng_class **, const void *, const void *, size_t))
152*0957b409SSimon J. Gerraty &br_hmac_drbg_init,
153*0957b409SSimon J. Gerraty (void (*)(const br_prng_class **, void *, size_t))
154*0957b409SSimon J. Gerraty &br_hmac_drbg_generate,
155*0957b409SSimon J. Gerraty (void (*)(const br_prng_class **, const void *, size_t))
156*0957b409SSimon J. Gerraty &br_hmac_drbg_update
157*0957b409SSimon J. Gerraty };
158