text: /**********************************************************************
   * Copyright (c) 2014 Pieter Wuille                                   *
   * Distributed under the MIT software license, see the accompanying   *
   * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
   **********************************************************************/
  
  #ifndef _SECP256K1_HASH_IMPL_H_
  #define _SECP256K1_HASH_IMPL_H_
  
  #include "hash.h"
  
  #include <stdlib.h>
  #include <stdint.h>
  #include <string.h>
  
  #define Ch(x,y,z) ((z) ^ ((x) & ((y) ^ (z))))
  #define Maj(x,y,z) (((x) & (y)) | ((z) & ((x) | (y))))
  #define Sigma0(x) (((x) >> 2 | (x) << 30) ^ ((x) >> 13 | (x) << 19) ^ ((x) >> 22 | (x) << 10))
  #define Sigma1(x) (((x) >> 6 | (x) << 26) ^ ((x) >> 11 | (x) << 21) ^ ((x) >> 25 | (x) << 7))
  #define sigma0(x) (((x) >> 7 | (x) << 25) ^ ((x) >> 18 | (x) << 14) ^ ((x) >> 3))
  #define sigma1(x) (((x) >> 17 | (x) << 15) ^ ((x) >> 19 | (x) << 13) ^ ((x) >> 10))
  
  #define Round(a,b,c,d,e,f,g,h,k,w) do { \
      uint32_t t1 = (h) + Sigma1(e) + Ch((e), (f), (g)) + (k) + (w); \
      uint32_t t2 = Sigma0(a) + Maj((a), (b), (c)); \
      (d) += t1; \
      (h) = t1 + t2; \
  } while(0)
  
  #ifdef WORDS_BIGENDIAN
  #define BE32(x) (x)
  #else
  #define BE32(p) ((((p) & 0xFF) << 24) | (((p) & 0xFF00) << 8) | (((p) & 0xFF0000) >> 8) | (((p) & 0xFF000000) >> 24))
  #endif
  
  static void secp256k1_sha256_initialize(secp256k1_sha256_t *hash) {
      hash->s[0] = 0x6a09e667ul;
      hash->s[1] = 0xbb67ae85ul;
      hash->s[2] = 0x3c6ef372ul;
      hash->s[3] = 0xa54ff53aul;
      hash->s[4] = 0x510e527ful;
      hash->s[5] = 0x9b05688cul;
      hash->s[6] = 0x1f83d9abul;
      hash->s[7] = 0x5be0cd19ul;
      hash->bytes = 0;
  }
  
  /** Perform one SHA-256 transformation, processing 16 big endian 32-bit words. */
  static void secp256k1_sha256_transform(uint32_t* s, const uint32_t* chunk) {
      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];
      uint32_t w0, w1, w2, w3, w4, w5, w6, w7, w8, w9, w10, w11, w12, w13, w14, w15;
  
      Round(a, b, c, d, e, f, g, h, 0x428a2f98, w0 = BE32(chunk[0]));
      Round(h, a, b, c, d, e, f, g, 0x71374491, w1 = BE32(chunk[1]));
      Round(g, h, a, b, c, d, e, f, 0xb5c0fbcf, w2 = BE32(chunk[2]));
      Round(f, g, h, a, b, c, d, e, 0xe9b5dba5, w3 = BE32(chunk[3]));
      Round(e, f, g, h, a, b, c, d, 0x3956c25b, w4 = BE32(chunk[4]));
      Round(d, e, f, g, h, a, b, c, 0x59f111f1, w5 = BE32(chunk[5]));
      Round(c, d, e, f, g, h, a, b, 0x923f82a4, w6 = BE32(chunk[6]));
      Round(b, c, d, e, f, g, h, a, 0xab1c5ed5, w7 = BE32(chunk[7]));
      Round(a, b, c, d, e, f, g, h, 0xd807aa98, w8 = BE32(chunk[8]));
      Round(h, a, b, c, d, e, f, g, 0x12835b01, w9 = BE32(chunk[9]));
      Round(g, h, a, b, c, d, e, f, 0x243185be, w10 = BE32(chunk[10]));
      Round(f, g, h, a, b, c, d, e, 0x550c7dc3, w11 = BE32(chunk[11]));
      Round(e, f, g, h, a, b, c, d, 0x72be5d74, w12 = BE32(chunk[12]));
      Round(d, e, f, g, h, a, b, c, 0x80deb1fe, w13 = BE32(chunk[13]));
      Round(c, d, e, f, g, h, a, b, 0x9bdc06a7, w14 = BE32(chunk[14]));
      Round(b, c, d, e, f, g, h, a, 0xc19bf174, w15 = BE32(chunk[15]));
  
      Round(a, b, c, d, e, f, g, h, 0xe49b69c1, w0 += sigma1(w14) + w9 + sigma0(w1));
      Round(h, a, b, c, d, e, f, g, 0xefbe4786, w1 += sigma1(w15) + w10 + sigma0(w2));
      Round(g, h, a, b, c, d, e, f, 0x0fc19dc6, w2 += sigma1(w0) + w11 + sigma0(w3));
      Round(f, g, h, a, b, c, d, e, 0x240ca1cc, w3 += sigma1(w1) + w12 + sigma0(w4));
      Round(e, f, g, h, a, b, c, d, 0x2de92c6f, w4 += sigma1(w2) + w13 + sigma0(w5));
      Round(d, e, f, g, h, a, b, c, 0x4a7484aa, w5 += sigma1(w3) + w14 + sigma0(w6));
      Round(c, d, e, f, g, h, a, b, 0x5cb0a9dc, w6 += sigma1(w4) + w15 + sigma0(w7));
      Round(b, c, d, e, f, g, h, a, 0x76f988da, w7 += sigma1(w5) + w0 + sigma0(w8));
      Round(a, b, c, d, e, f, g, h, 0x983e5152, w8 += sigma1(w6) + w1 + sigma0(w9));
      Round(h, a, b, c, d, e, f, g, 0xa831c66d, w9 += sigma1(w7) + w2 + sigma0(w10));
      Round(g, h, a, b, c, d, e, f, 0xb00327c8, w10 += sigma1(w8) + w3 + sigma0(w11));
      Round(f, g, h, a, b, c, d, e, 0xbf597fc7, w11 += sigma1(w9) + w4 + sigma0(w12));
      Round(e, f, g, h, a, b, c, d, 0xc6e00bf3, w12 += sigma1(w10) + w5 + sigma0(w13));
      Round(d, e, f, g, h, a, b, c, 0xd5a79147, w13 += sigma1(w11) + w6 + sigma0(w14));
      Round(c, d, e, f, g, h, a, b, 0x06ca6351, w14 += sigma1(w12) + w7 + sigma0(w15));
      Round(b, c, d, e, f, g, h, a, 0x14292967, w15 += sigma1(w13) + w8 + sigma0(w0));
  
      Round(a, b, c, d, e, f, g, h, 0x27b70a85, w0 += sigma1(w14) + w9 + sigma0(w1));
      Round(h, a, b, c, d, e, f, g, 0x2e1b2138, w1 += sigma1(w15) + w10 + sigma0(w2));
      Round(g, h, a, b, c, d, e, f, 0x4d2c6dfc, w2 += sigma1(w0) + w11 + sigma0(w3));
      Round(f, g, h, a, b, c, d, e, 0x53380d13, w3 += sigma1(w1) + w12 + sigma0(w4));
      Round(e, f, g, h, a, b, c, d, 0x650a7354, w4 += sigma1(w2) + w13 + sigma0(w5));
      Round(d, e, f, g, h, a, b, c, 0x766a0abb, w5 += sigma1(w3) + w14 + sigma0(w6));
      Round(c, d, e, f, g, h, a, b, 0x81c2c92e, w6 += sigma1(w4) + w15 + sigma0(w7));
      Round(b, c, d, e, f, g, h, a, 0x92722c85, w7 += sigma1(w5) + w0 + sigma0(w8));
      Round(a, b, c, d, e, f, g, h, 0xa2bfe8a1, w8 += sigma1(w6) + w1 + sigma0(w9));
      Round(h, a, b, c, d, e, f, g, 0xa81a664b, w9 += sigma1(w7) + w2 + sigma0(w10));
      Round(g, h, a, b, c, d, e, f, 0xc24b8b70, w10 += sigma1(w8) + w3 + sigma0(w11));
      Round(f, g, h, a, b, c, d, e, 0xc76c51a3, w11 += sigma1(w9) + w4 + sigma0(w12));
      Round(e, f, g, h, a, b, c, d, 0xd192e819, w12 += sigma1(w10) + w5 + sigma0(w13));
      Round(d, e, f, g, h, a, b, c, 0xd6990624, w13 += sigma1(w11) + w6 + sigma0(w14));
      Round(c, d, e, f, g, h, a, b, 0xf40e3585, w14 += sigma1(w12) + w7 + sigma0(w15));
      Round(b, c, d, e, f, g, h, a, 0x106aa070, w15 += sigma1(w13) + w8 + sigma0(w0));
  
      Round(a, b, c, d, e, f, g, h, 0x19a4c116, w0 += sigma1(w14) + w9 + sigma0(w1));
      Round(h, a, b, c, d, e, f, g, 0x1e376c08, w1 += sigma1(w15) + w10 + sigma0(w2));
      Round(g, h, a, b, c, d, e, f, 0x2748774c, w2 += sigma1(w0) + w11 + sigma0(w3));
      Round(f, g, h, a, b, c, d, e, 0x34b0bcb5, w3 += sigma1(w1) + w12 + sigma0(w4));
      Round(e, f, g, h, a, b, c, d, 0x391c0cb3, w4 += sigma1(w2) + w13 + sigma0(w5));
      Round(d, e, f, g, h, a, b, c, 0x4ed8aa4a, w5 += sigma1(w3) + w14 + sigma0(w6));
      Round(c, d, e, f, g, h, a, b, 0x5b9cca4f, w6 += sigma1(w4) + w15 + sigma0(w7));
      Round(b, c, d, e, f, g, h, a, 0x682e6ff3, w7 += sigma1(w5) + w0 + sigma0(w8));
      Round(a, b, c, d, e, f, g, h, 0x748f82ee, w8 += sigma1(w6) + w1 + sigma0(w9));
      Round(h, a, b, c, d, e, f, g, 0x78a5636f, w9 += sigma1(w7) + w2 + sigma0(w10));
      Round(g, h, a, b, c, d, e, f, 0x84c87814, w10 += sigma1(w8) + w3 + sigma0(w11));
      Round(f, g, h, a, b, c, d, e, 0x8cc70208, w11 += sigma1(w9) + w4 + sigma0(w12));
      Round(e, f, g, h, a, b, c, d, 0x90befffa, w12 += sigma1(w10) + w5 + sigma0(w13));
      Round(d, e, f, g, h, a, b, c, 0xa4506ceb, w13 += sigma1(w11) + w6 + sigma0(w14));
      Round(c, d, e, f, g, h, a, b, 0xbef9a3f7, w14 + sigma1(w12) + w7 + sigma0(w15));
      Round(b, c, d, e, f, g, h, a, 0xc67178f2, w15 + sigma1(w13) + w8 + sigma0(w0));
  
      s[0] += a;
      s[1] += b;
      s[2] += c;
      s[3] += d;
      s[4] += e;
      s[5] += f;
      s[6] += g;
      s[7] += h;
  }
  
  static void secp256k1_sha256_write(secp256k1_sha256_t *hash, const unsigned char *data, size_t len) {
      size_t bufsize = hash->bytes & 0x3F;
      hash->bytes += len;
      while (bufsize + len >= 64) {
          /* Fill the buffer, and process it. */
          memcpy(((unsigned char*)hash->buf) + bufsize, data, 64 - bufsize);
          data += 64 - bufsize;
          len -= 64 - bufsize;
          secp256k1_sha256_transform(hash->s, hash->buf);
          bufsize = 0;
      }
      if (len) {
          /* Fill the buffer with what remains. */
          memcpy(((unsigned char*)hash->buf) + bufsize, data, len);
      }
  }
  
  static void secp256k1_sha256_finalize(secp256k1_sha256_t *hash, unsigned char *out32) {
      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};
      uint32_t sizedesc[2];
      uint32_t out[8];
      int i = 0;
      sizedesc[0] = (uint32_t)BE32(hash->bytes >> 29);
      sizedesc[1] = (uint32_t)BE32(hash->bytes << 3);
      secp256k1_sha256_write(hash, pad, 1 + ((119 - (hash->bytes % 64)) % 64));
      secp256k1_sha256_write(hash, (const unsigned char*)sizedesc, 8);
      for (i = 0; i < 8; i++) {
          out[i] = BE32(hash->s[i]);
          hash->s[i] = 0;
      }
      memcpy(out32, (const unsigned char*)out, 32);
  }
  
  static void secp256k1_hmac_sha256_initialize(secp256k1_hmac_sha256_t *hash, const unsigned char *key, size_t keylen) {
      int n;
      unsigned char rkey[64];
      if (keylen <= 64) {
          memcpy(rkey, key, keylen);
          memset(rkey + keylen, 0, 64 - keylen);
      } else {
          secp256k1_sha256_t sha256;
          secp256k1_sha256_initialize(&sha256);
          secp256k1_sha256_write(&sha256, key, keylen);
          secp256k1_sha256_finalize(&sha256, rkey);
          memset(rkey + 32, 0, 32);
      }
  
      secp256k1_sha256_initialize(&hash->outer);
      for (n = 0; n < 64; n++) {
          rkey[n] ^= 0x5c;
      }
      secp256k1_sha256_write(&hash->outer, rkey, 64);
  
      secp256k1_sha256_initialize(&hash->inner);
      for (n = 0; n < 64; n++) {
          rkey[n] ^= 0x5c ^ 0x36;
      }
      secp256k1_sha256_write(&hash->inner, rkey, 64);
      memset(rkey, 0, 64);
  }
  
  static void secp256k1_hmac_sha256_write(secp256k1_hmac_sha256_t *hash, const unsigned char *data, size_t size) {
      secp256k1_sha256_write(&hash->inner, data, size);
  }
  
  static void secp256k1_hmac_sha256_finalize(secp256k1_hmac_sha256_t *hash, unsigned char *out32) {
      unsigned char temp[32];
      secp256k1_sha256_finalize(&hash->inner, temp);
      secp256k1_sha256_write(&hash->outer, temp, 32);
      memset(temp, 0, 32);
      secp256k1_sha256_finalize(&hash->outer, out32);
  }
  
  
  static void secp256k1_rfc6979_hmac_sha256_initialize(secp256k1_rfc6979_hmac_sha256_t *rng, const unsigned char *key, size_t keylen) {
      secp256k1_hmac_sha256_t hmac;
      static const unsigned char zero[1] = {0x00};
      static const unsigned char one[1] = {0x01};
  
      memset(rng->v, 0x01, 32); /* RFC6979 3.2.b. */
      memset(rng->k, 0x00, 32); /* RFC6979 3.2.c. */
  
      /* RFC6979 3.2.d. */
      secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
      secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
      secp256k1_hmac_sha256_write(&hmac, zero, 1);
      secp256k1_hmac_sha256_write(&hmac, key, keylen);
      secp256k1_hmac_sha256_finalize(&hmac, rng->k);
      secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
      secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
      secp256k1_hmac_sha256_finalize(&hmac, rng->v);
  
      /* RFC6979 3.2.f. */
      secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
      secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
      secp256k1_hmac_sha256_write(&hmac, one, 1);
      secp256k1_hmac_sha256_write(&hmac, key, keylen);
      secp256k1_hmac_sha256_finalize(&hmac, rng->k);
      secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
      secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
      secp256k1_hmac_sha256_finalize(&hmac, rng->v);
      rng->retry = 0;
  }
  
  static void secp256k1_rfc6979_hmac_sha256_generate(secp256k1_rfc6979_hmac_sha256_t *rng, unsigned char *out, size_t outlen) {
      /* RFC6979 3.2.h. */
      static const unsigned char zero[1] = {0x00};
      if (rng->retry) {
          secp256k1_hmac_sha256_t hmac;
          secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
          secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
          secp256k1_hmac_sha256_write(&hmac, zero, 1);
          secp256k1_hmac_sha256_finalize(&hmac, rng->k);
          secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
          secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
          secp256k1_hmac_sha256_finalize(&hmac, rng->v);
      }
  
      while (outlen > 0) {
          secp256k1_hmac_sha256_t hmac;
          int now = (int)outlen;
          secp256k1_hmac_sha256_initialize(&hmac, rng->k, 32);
          secp256k1_hmac_sha256_write(&hmac, rng->v, 32);
          secp256k1_hmac_sha256_finalize(&hmac, rng->v);
          if (now > 32) {
              now = 32;
          }
          memcpy(out, rng->v, now);
          out += now;
          outlen -= now;
      }
  
      rng->retry = 1;
  }
  
  static void secp256k1_rfc6979_hmac_sha256_finalize(secp256k1_rfc6979_hmac_sha256_t *rng) {
      memset(rng->k, 0, 32);
      memset(rng->v, 0, 32);
      rng->retry = 0;
  }
  
  
  #undef Round
  #undef sigma0
  #undef sigma1
  #undef Sigma0
  #undef Sigma1
  #undef Ch
  #undef Maj
  #undef ReadBE32
  #undef WriteBE32
  
  #endif
  