1 /**********************************************************************
2  * Copyright (c) 2014 Pieter Wuille                                   *
3  * Distributed under the MIT software license, see the accompanying   *
4  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
5  **********************************************************************/
6 
7 #ifndef SECP256K1_HASH_IMPL_H
8 #define SECP256K1_HASH_IMPL_H
9 
10 #include "hash.h"
11 #include "util.h"
12 
13 #include <stdlib.h>
14 #include <stdint.h>
15 #include <string.h>
16 
17 #define Ch(x,y,z) ((z) ^ ((x) & ((y) ^ (z))))
18 #define Maj(x,y,z) (((x) & (y)) | ((z) & ((x) | (y))))
19 #define Sigma0(x) (((x) >> 2 | (x) << 30) ^ ((x) >> 13 | (x) << 19) ^ ((x) >> 22 | (x) << 10))
20 #define Sigma1(x) (((x) >> 6 | (x) << 26) ^ ((x) >> 11 | (x) << 21) ^ ((x) >> 25 | (x) << 7))
21 #define sigma0(x) (((x) >> 7 | (x) << 25) ^ ((x) >> 18 | (x) << 14) ^ ((x) >> 3))
22 #define sigma1(x) (((x) >> 17 | (x) << 15) ^ ((x) >> 19 | (x) << 13) ^ ((x) >> 10))
23 
24 #define Round(a,b,c,d,e,f,g,h,k,w) do { \
25     uint32_t t1 = (h) + Sigma1(e) + Ch((e), (f), (g)) + (k) + (w); \
26     uint32_t t2 = Sigma0(a) + Maj((a), (b), (c)); \
27     (d) += t1; \
28     (h) = t1 + t2; \
29 } while(0)
30 
31 #if defined(SECP256K1_BIG_ENDIAN)
32 #define BE32(x) (x)
33 #elif defined(SECP256K1_LITTLE_ENDIAN)
34 #define BE32(p) ((((p) & 0xFF) << 24) | (((p) & 0xFF00) << 8) | (((p) & 0xFF0000) >> 8) | (((p) & 0xFF000000) >> 24))
35 #endif
36 
secp256k1_sha256_initialize(secp256k1_sha256 * hash)37 static void secp256k1_sha256_initialize(secp256k1_sha256 *hash) {
38     hash->s[0] = 0x6a09e667ul;
39     hash->s[1] = 0xbb67ae85ul;
40     hash->s[2] = 0x3c6ef372ul;
41     hash->s[3] = 0xa54ff53aul;
42     hash->s[4] = 0x510e527ful;
43     hash->s[5] = 0x9b05688cul;
44     hash->s[6] = 0x1f83d9abul;
45     hash->s[7] = 0x5be0cd19ul;
46     hash->bytes = 0;
47 }
48 
49 /** Perform one SHA-256 transformation, processing 16 big endian 32-bit words. */
secp256k1_sha256_transform(uint32_t * s,const uint32_t * chunk)50 static void secp256k1_sha256_transform(uint32_t* s, const uint32_t* chunk) {
51     uint32_t a = s[0], b = s[1], c = s[2], d = s[3], e = s[4], f = s[5], g = s[6], h = s[7];
52     uint32_t w0, w1, w2, w3, w4, w5, w6, w7, w8, w9, w10, w11, w12, w13, w14, w15;
53 
54     Round(a, b, c, d, e, f, g, h, 0x428a2f98, w0 = BE32(chunk[0]));
55     Round(h, a, b, c, d, e, f, g, 0x71374491, w1 = BE32(chunk[1]));
56     Round(g, h, a, b, c, d, e, f, 0xb5c0fbcf, w2 = BE32(chunk[2]));
57     Round(f, g, h, a, b, c, d, e, 0xe9b5dba5, w3 = BE32(chunk[3]));
58     Round(e, f, g, h, a, b, c, d, 0x3956c25b, w4 = BE32(chunk[4]));
59     Round(d, e, f, g, h, a, b, c, 0x59f111f1, w5 = BE32(chunk[5]));
60     Round(c, d, e, f, g, h, a, b, 0x923f82a4, w6 = BE32(chunk[6]));
61     Round(b, c, d, e, f, g, h, a, 0xab1c5ed5, w7 = BE32(chunk[7]));
62     Round(a, b, c, d, e, f, g, h, 0xd807aa98, w8 = BE32(chunk[8]));
63     Round(h, a, b, c, d, e, f, g, 0x12835b01, w9 = BE32(chunk[9]));
64     Round(g, h, a, b, c, d, e, f, 0x243185be, w10 = BE32(chunk[10]));
65     Round(f, g, h, a, b, c, d, e, 0x550c7dc3, w11 = BE32(chunk[11]));
66     Round(e, f, g, h, a, b, c, d, 0x72be5d74, w12 = BE32(chunk[12]));
67     Round(d, e, f, g, h, a, b, c, 0x80deb1fe, w13 = BE32(chunk[13]));
68     Round(c, d, e, f, g, h, a, b, 0x9bdc06a7, w14 = BE32(chunk[14]));
69     Round(b, c, d, e, f, g, h, a, 0xc19bf174, w15 = BE32(chunk[15]));
70 
71     Round(a, b, c, d, e, f, g, h, 0xe49b69c1, w0 += sigma1(w14) + w9 + sigma0(w1));
72     Round(h, a, b, c, d, e, f, g, 0xefbe4786, w1 += sigma1(w15) + w10 + sigma0(w2));
73     Round(g, h, a, b, c, d, e, f, 0x0fc19dc6, w2 += sigma1(w0) + w11 + sigma0(w3));
74     Round(f, g, h, a, b, c, d, e, 0x240ca1cc, w3 += sigma1(w1) + w12 + sigma0(w4));
75     Round(e, f, g, h, a, b, c, d, 0x2de92c6f, w4 += sigma1(w2) + w13 + sigma0(w5));
76     Round(d, e, f, g, h, a, b, c, 0x4a7484aa, w5 += sigma1(w3) + w14 + sigma0(w6));
77     Round(c, d, e, f, g, h, a, b, 0x5cb0a9dc, w6 += sigma1(w4) + w15 + sigma0(w7));
78     Round(b, c, d, e, f, g, h, a, 0x76f988da, w7 += sigma1(w5) + w0 + sigma0(w8));
79     Round(a, b, c, d, e, f, g, h, 0x983e5152, w8 += sigma1(w6) + w1 + sigma0(w9));
80     Round(h, a, b, c, d, e, f, g, 0xa831c66d, w9 += sigma1(w7) + w2 + sigma0(w10));
81     Round(g, h, a, b, c, d, e, f, 0xb00327c8, w10 += sigma1(w8) + w3 + sigma0(w11));
82     Round(f, g, h, a, b, c, d, e, 0xbf597fc7, w11 += sigma1(w9) + w4 + sigma0(w12));
83     Round(e, f, g, h, a, b, c, d, 0xc6e00bf3, w12 += sigma1(w10) + w5 + sigma0(w13));
84     Round(d, e, f, g, h, a, b, c, 0xd5a79147, w13 += sigma1(w11) + w6 + sigma0(w14));
85     Round(c, d, e, f, g, h, a, b, 0x06ca6351, w14 += sigma1(w12) + w7 + sigma0(w15));
86     Round(b, c, d, e, f, g, h, a, 0x14292967, w15 += sigma1(w13) + w8 + sigma0(w0));
87 
88     Round(a, b, c, d, e, f, g, h, 0x27b70a85, w0 += sigma1(w14) + w9 + sigma0(w1));
89     Round(h, a, b, c, d, e, f, g, 0x2e1b2138, w1 += sigma1(w15) + w10 + sigma0(w2));
90     Round(g, h, a, b, c, d, e, f, 0x4d2c6dfc, w2 += sigma1(w0) + w11 + sigma0(w3));
91     Round(f, g, h, a, b, c, d, e, 0x53380d13, w3 += sigma1(w1) + w12 + sigma0(w4));
92     Round(e, f, g, h, a, b, c, d, 0x650a7354, w4 += sigma1(w2) + w13 + sigma0(w5));
93     Round(d, e, f, g, h, a, b, c, 0x766a0abb, w5 += sigma1(w3) + w14 + sigma0(w6));
94     Round(c, d, e, f, g, h, a, b, 0x81c2c92e, w6 += sigma1(w4) + w15 + sigma0(w7));
95     Round(b, c, d, e, f, g, h, a, 0x92722c85, w7 += sigma1(w5) + w0 + sigma0(w8));
96     Round(a, b, c, d, e, f, g, h, 0xa2bfe8a1, w8 += sigma1(w6) + w1 + sigma0(w9));
97     Round(h, a, b, c, d, e, f, g, 0xa81a664b, w9 += sigma1(w7) + w2 + sigma0(w10));
98     Round(g, h, a, b, c, d, e, f, 0xc24b8b70, w10 += sigma1(w8) + w3 + sigma0(w11));
99     Round(f, g, h, a, b, c, d, e, 0xc76c51a3, w11 += sigma1(w9) + w4 + sigma0(w12));
100     Round(e, f, g, h, a, b, c, d, 0xd192e819, w12 += sigma1(w10) + w5 + sigma0(w13));
101     Round(d, e, f, g, h, a, b, c, 0xd6990624, w13 += sigma1(w11) + w6 + sigma0(w14));
102     Round(c, d, e, f, g, h, a, b, 0xf40e3585, w14 += sigma1(w12) + w7 + sigma0(w15));
103     Round(b, c, d, e, f, g, h, a, 0x106aa070, w15 += sigma1(w13) + w8 + sigma0(w0));
104 
105     Round(a, b, c, d, e, f, g, h, 0x19a4c116, w0 += sigma1(w14) + w9 + sigma0(w1));
106     Round(h, a, b, c, d, e, f, g, 0x1e376c08, w1 += sigma1(w15) + w10 + sigma0(w2));
107     Round(g, h, a, b, c, d, e, f, 0x2748774c, w2 += sigma1(w0) + w11 + sigma0(w3));
108     Round(f, g, h, a, b, c, d, e, 0x34b0bcb5, w3 += sigma1(w1) + w12 + sigma0(w4));
109     Round(e, f, g, h, a, b, c, d, 0x391c0cb3, w4 += sigma1(w2) + w13 + sigma0(w5));
110     Round(d, e, f, g, h, a, b, c, 0x4ed8aa4a, w5 += sigma1(w3) + w14 + sigma0(w6));
111     Round(c, d, e, f, g, h, a, b, 0x5b9cca4f, w6 += sigma1(w4) + w15 + sigma0(w7));
112     Round(b, c, d, e, f, g, h, a, 0x682e6ff3, w7 += sigma1(w5) + w0 + sigma0(w8));
113     Round(a, b, c, d, e, f, g, h, 0x748f82ee, w8 += sigma1(w6) + w1 + sigma0(w9));
114     Round(h, a, b, c, d, e, f, g, 0x78a5636f, w9 += sigma1(w7) + w2 + sigma0(w10));
115     Round(g, h, a, b, c, d, e, f, 0x84c87814, w10 += sigma1(w8) + w3 + sigma0(w11));
116     Round(f, g, h, a, b, c, d, e, 0x8cc70208, w11 += sigma1(w9) + w4 + sigma0(w12));
117     Round(e, f, g, h, a, b, c, d, 0x90befffa, w12 += sigma1(w10) + w5 + sigma0(w13));
118     Round(d, e, f, g, h, a, b, c, 0xa4506ceb, w13 += sigma1(w11) + w6 + sigma0(w14));
119     Round(c, d, e, f, g, h, a, b, 0xbef9a3f7, w14 + sigma1(w12) + w7 + sigma0(w15));
120     Round(b, c, d, e, f, g, h, a, 0xc67178f2, w15 + sigma1(w13) + w8 + sigma0(w0));
121 
122     s[0] += a;
123     s[1] += b;
124     s[2] += c;
125     s[3] += d;
126     s[4] += e;
127     s[5] += f;
128     s[6] += g;
129     s[7] += h;
130 }
131 
secp256k1_sha256_write(secp256k1_sha256 * hash,const unsigned char * data,size_t len)132 static void secp256k1_sha256_write(secp256k1_sha256 *hash, const unsigned char *data, size_t len) {
133     size_t bufsize = hash->bytes & 0x3F;
134     hash->bytes += len;
135     VERIFY_CHECK(hash->bytes >= len);
136     while (len >= 64 - bufsize) {
137         /* Fill the buffer, and process it. */
138         size_t chunk_len = 64 - bufsize;
139         memcpy(((unsigned char*)hash->buf) + bufsize, data, chunk_len);
140         data += chunk_len;
141         len -= chunk_len;
142         secp256k1_sha256_transform(hash->s, hash->buf);
143         bufsize = 0;
144     }
145     if (len) {
146         /* Fill the buffer with what remains. */
147         memcpy(((unsigned char*)hash->buf) + bufsize, data, len);
148     }
149 }
150 
secp256k1_sha256_finalize(secp256k1_sha256 * hash,unsigned char * out32)151 static void secp256k1_sha256_finalize(secp256k1_sha256 *hash, unsigned char *out32) {
152     static const unsigned char pad[64] = {0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
153     uint32_t sizedesc[2];
154     uint32_t out[8];
155     int i = 0;
156     sizedesc[0] = BE32(hash->bytes >> 29);
157     sizedesc[1] = BE32(hash->bytes << 3);
158     secp256k1_sha256_write(hash, pad, 1 + ((119 - (hash->bytes % 64)) % 64));
159     secp256k1_sha256_write(hash, (const unsigned char*)sizedesc, 8);
160     for (i = 0; i < 8; i++) {
161         out[i] = BE32(hash->s[i]);
162         hash->s[i] = 0;
163     }
164     memcpy(out32, (const unsigned char*)out, 32);
165 }
166 
167 /* Initializes a sha256 struct and writes the 64 byte string
168  * SHA256(tag)||SHA256(tag) into it. */
secp256k1_sha256_initialize_tagged(secp256k1_sha256 * hash,const unsigned char * tag,size_t taglen)169 static void secp256k1_sha256_initialize_tagged(secp256k1_sha256 *hash, const unsigned char *tag, size_t taglen) {
170     unsigned char buf[32];
171     secp256k1_sha256_initialize(hash);
172     secp256k1_sha256_write(hash, tag, taglen);
173     secp256k1_sha256_finalize(hash, buf);
174 
175     secp256k1_sha256_initialize(hash);
176     secp256k1_sha256_write(hash, buf, 32);
177     secp256k1_sha256_write(hash, buf, 32);
178 }
179 
secp256k1_hmac_sha256_initialize(secp256k1_hmac_sha256 * hash,const unsigned char * key,size_t keylen)180 static void secp256k1_hmac_sha256_initialize(secp256k1_hmac_sha256 *hash, const unsigned char *key, size_t keylen) {
181     size_t n;
182     unsigned char rkey[64];
183     if (keylen <= sizeof(rkey)) {
184         memcpy(rkey, key, keylen);
185         memset(rkey + keylen, 0, sizeof(rkey) - keylen);
186     } else {
187         secp256k1_sha256 sha256;
188         secp256k1_sha256_initialize(&sha256);
189         secp256k1_sha256_write(&sha256, key, keylen);
190         secp256k1_sha256_finalize(&sha256, rkey);
191         memset(rkey + 32, 0, 32);
192     }
193 
194     secp256k1_sha256_initialize(&hash->outer);
195     for (n = 0; n < sizeof(rkey); n++) {
196         rkey[n] ^= 0x5c;
197     }
198     secp256k1_sha256_write(&hash->outer, rkey, sizeof(rkey));
199 
200     secp256k1_sha256_initialize(&hash->inner);
201     for (n = 0; n < sizeof(rkey); n++) {
202         rkey[n] ^= 0x5c ^ 0x36;
203     }
204     secp256k1_sha256_write(&hash->inner, rkey, sizeof(rkey));
205     memset(rkey, 0, sizeof(rkey));
206 }
207 
secp256k1_hmac_sha256_write(secp256k1_hmac_sha256 * hash,const unsigned char * data,size_t size)208 static void secp256k1_hmac_sha256_write(secp256k1_hmac_sha256 *hash, const unsigned char *data, size_t size) {
209     secp256k1_sha256_write(&hash->inner, data, size);
210 }
211 
secp256k1_hmac_sha256_finalize(secp256k1_hmac_sha256 * hash,unsigned char * out32)212 static void secp256k1_hmac_sha256_finalize(secp256k1_hmac_sha256 *hash, unsigned char *out32) {
213     unsigned char temp[32];
214     secp256k1_sha256_finalize(&hash->inner, temp);
215     secp256k1_sha256_write(&hash->outer, temp, 32);
216     memset(temp, 0, 32);
217     secp256k1_sha256_finalize(&hash->outer, out32);
218 }
219 
220 
secp256k1_rfc6979_hmac_sha256_initialize(secp256k1_rfc6979_hmac_sha256 * rng,const unsigned char * key,size_t keylen)221 static void secp256k1_rfc6979_hmac_sha256_initialize(secp256k1_rfc6979_hmac_sha256 *rng, const unsigned char *key, size_t keylen) {
222     secp256k1_hmac_sha256 hmac;
223     static const unsigned char zero[1] = {0x00};
224     static const unsigned char one[1] = {0x01};
225 
226     memset(rng->v, 0x01, 32); /* RFC6979 3.2.b. */
227     memset(rng->k, 0x00, 32); /* RFC6979 3.2.c. */
228 
229     /* RFC6979 3.2.d. */
230     secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
231     secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
232     secp256k1_hmac_sha256_write(&hmac, zero, 1);
233     secp256k1_hmac_sha256_write(&hmac, key, keylen);
234     secp256k1_hmac_sha256_finalize(&hmac, rng->k);
235     secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
236     secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
237     secp256k1_hmac_sha256_finalize(&hmac, rng->v);
238 
239     /* RFC6979 3.2.f. */
240     secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
241     secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
242     secp256k1_hmac_sha256_write(&hmac, one, 1);
243     secp256k1_hmac_sha256_write(&hmac, key, keylen);
244     secp256k1_hmac_sha256_finalize(&hmac, rng->k);
245     secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
246     secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
247     secp256k1_hmac_sha256_finalize(&hmac, rng->v);
248     rng->retry = 0;
249 }
250 
secp256k1_rfc6979_hmac_sha256_generate(secp256k1_rfc6979_hmac_sha256 * rng,unsigned char * out,size_t outlen)251 static void secp256k1_rfc6979_hmac_sha256_generate(secp256k1_rfc6979_hmac_sha256 *rng, unsigned char *out, size_t outlen) {
252     /* RFC6979 3.2.h. */
253     static const unsigned char zero[1] = {0x00};
254     if (rng->retry) {
255         secp256k1_hmac_sha256 hmac;
256         secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
257         secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
258         secp256k1_hmac_sha256_write(&hmac, zero, 1);
259         secp256k1_hmac_sha256_finalize(&hmac, rng->k);
260         secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
261         secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
262         secp256k1_hmac_sha256_finalize(&hmac, rng->v);
263     }
264 
265     while (outlen > 0) {
266         secp256k1_hmac_sha256 hmac;
267         int now = outlen;
268         secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
269         secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
270         secp256k1_hmac_sha256_finalize(&hmac, rng->v);
271         if (now > 32) {
272             now = 32;
273         }
274         memcpy(out, rng->v, now);
275         out += now;
276         outlen -= now;
277     }
278 
279     rng->retry = 1;
280 }
281 
secp256k1_rfc6979_hmac_sha256_finalize(secp256k1_rfc6979_hmac_sha256 * rng)282 static void secp256k1_rfc6979_hmac_sha256_finalize(secp256k1_rfc6979_hmac_sha256 *rng) {
283     memset(rng->k, 0, 32);
284     memset(rng->v, 0, 32);
285     rng->retry = 0;
286 }
287 
288 #undef BE32
289 #undef Round
290 #undef sigma1
291 #undef sigma0
292 #undef Sigma1
293 #undef Sigma0
294 #undef Maj
295 #undef Ch
296 
297 #endif /* SECP256K1_HASH_IMPL_H */
298