text: // Copyright (c) 2014-2020, The Monero Project
  // 
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  /*
   * The blake256_* and blake224_* functions are largely copied from
   * blake256_light.c and blake224_light.c from the BLAKE website:
   *
   *     https://131002.net/blake/
   *
   * The hmac_* functions implement HMAC-BLAKE-256 and HMAC-BLAKE-224.
   * HMAC is specified by RFC 2104.
   */
  
  #include <string.h>
  #include <stdint.h>
  #include <memwipe.h>
  #include "blake256.h"
  
  #define U8TO32(p) \
      (((uint32_t)((p)[0]) << 24) | ((uint32_t)((p)[1]) << 16) |    \
       ((uint32_t)((p)[2]) <<  8) | ((uint32_t)((p)[3])      ))
  #define U32TO8(p, v) \
      (p)[0] = (uint8_t)((v) >> 24); (p)[1] = (uint8_t)((v) >> 16); \
      (p)[2] = (uint8_t)((v) >>  8); (p)[3] = (uint8_t)((v)      );
  
  const uint8_t sigma[][16] = {
      { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,15},
      {14,10, 4, 8, 9,15,13, 6, 1,12, 0, 2,11, 7, 5, 3},
      {11, 8,12, 0, 5, 2,15,13,10,14, 3, 6, 7, 1, 9, 4},
      { 7, 9, 3, 1,13,12,11,14, 2, 6, 5,10, 4, 0,15, 8},
      { 9, 0, 5, 7, 2, 4,10,15,14, 1,11,12, 6, 8, 3,13},
      { 2,12, 6,10, 0,11, 8, 3, 4,13, 7, 5,15,14, 1, 9},
      {12, 5, 1,15,14,13, 4,10, 0, 7, 6, 3, 9, 2, 8,11},
      {13,11, 7,14,12, 1, 3, 9, 5, 0,15, 4, 8, 6, 2,10},
      { 6,15,14, 9,11, 3, 0, 8,12, 2,13, 7, 1, 4,10, 5},
      {10, 2, 8, 4, 7, 6, 1, 5,15,11, 9,14, 3,12,13, 0},
      { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,15},
      {14,10, 4, 8, 9,15,13, 6, 1,12, 0, 2,11, 7, 5, 3},
      {11, 8,12, 0, 5, 2,15,13,10,14, 3, 6, 7, 1, 9, 4},
      { 7, 9, 3, 1,13,12,11,14, 2, 6, 5,10, 4, 0,15, 8}
  };
  
  const uint32_t cst[16] = {
      0x243F6A88, 0x85A308D3, 0x13198A2E, 0x03707344,
      0xA4093822, 0x299F31D0, 0x082EFA98, 0xEC4E6C89,
      0x452821E6, 0x38D01377, 0xBE5466CF, 0x34E90C6C,
      0xC0AC29B7, 0xC97C50DD, 0x3F84D5B5, 0xB5470917
  };
  
  static const uint8_t padding[] = {
      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
  };
  
  
  void blake256_compress(state *S, const uint8_t *block) {
      uint32_t v[16], m[16], i;
  
  #define ROT(x,n) (((x)<<(32-n))|((x)>>(n)))
  #define G(a,b,c,d,e)                                      \
      v[a] += (m[sigma[i][e]] ^ cst[sigma[i][e+1]]) + v[b]; \
      v[d] = ROT(v[d] ^ v[a],16);                           \
      v[c] += v[d];                                         \
      v[b] = ROT(v[b] ^ v[c],12);                           \
      v[a] += (m[sigma[i][e+1]] ^ cst[sigma[i][e]])+v[b];   \
      v[d] = ROT(v[d] ^ v[a], 8);                           \
      v[c] += v[d];                                         \
      v[b] = ROT(v[b] ^ v[c], 7);
  
      for (i = 0; i < 16; ++i) m[i] = U8TO32(block + i * 4);
      for (i = 0; i < 8;  ++i) v[i] = S->h[i];
      v[ 8] = S->s[0] ^ 0x243F6A88;
      v[ 9] = S->s[1] ^ 0x85A308D3;
      v[10] = S->s[2] ^ 0x13198A2E;
      v[11] = S->s[3] ^ 0x03707344;
      v[12] = 0xA4093822;
      v[13] = 0x299F31D0;
      v[14] = 0x082EFA98;
      v[15] = 0xEC4E6C89;
  
      if (S->nullt == 0) {
          v[12] ^= S->t[0];
          v[13] ^= S->t[0];
          v[14] ^= S->t[1];
          v[15] ^= S->t[1];
      }
  
      for (i = 0; i < 14; ++i) {
          G(0, 4,  8, 12,  0);
          G(1, 5,  9, 13,  2);
          G(2, 6, 10, 14,  4);
          G(3, 7, 11, 15,  6);
          G(3, 4,  9, 14, 14);
          G(2, 7,  8, 13, 12);
          G(0, 5, 10, 15,  8);
          G(1, 6, 11, 12, 10);
      }
  
      for (i = 0; i < 16; ++i) S->h[i % 8] ^= v[i];
      for (i = 0; i < 8;  ++i) S->h[i] ^= S->s[i % 4];
  }
  
  void blake256_init(state *S) {
      S->h[0] = 0x6A09E667;
      S->h[1] = 0xBB67AE85;
      S->h[2] = 0x3C6EF372;
      S->h[3] = 0xA54FF53A;
      S->h[4] = 0x510E527F;
      S->h[5] = 0x9B05688C;
      S->h[6] = 0x1F83D9AB;
      S->h[7] = 0x5BE0CD19;
      S->t[0] = S->t[1] = S->buflen = S->nullt = 0;
      S->s[0] = S->s[1] = S->s[2] = S->s[3] = 0;
  }
  
  void blake224_init(state *S) {
      S->h[0] = 0xC1059ED8;
      S->h[1] = 0x367CD507;
      S->h[2] = 0x3070DD17;
      S->h[3] = 0xF70E5939;
      S->h[4] = 0xFFC00B31;
      S->h[5] = 0x68581511;
      S->h[6] = 0x64F98FA7;
      S->h[7] = 0xBEFA4FA4;
      S->t[0] = S->t[1] = S->buflen = S->nullt = 0;
      S->s[0] = S->s[1] = S->s[2] = S->s[3] = 0;
  }
  
  // datalen = number of bits
  void blake256_update(state *S, const uint8_t *data, uint64_t datalen) {
      int left = S->buflen >> 3;
      int fill = 64 - left;
  
      if (left && (((datalen >> 3)) >= (unsigned) fill)) {
          memcpy((void *) (S->buf + left), (void *) data, fill);
          S->t[0] += 512;
          if (S->t[0] == 0) S->t[1]++;
          blake256_compress(S, S->buf);
          data += fill;
          datalen -= (fill << 3);
          left = 0;
      }
  
      while (datalen >= 512) {
          S->t[0] += 512;
          if (S->t[0] == 0) S->t[1]++;
          blake256_compress(S, data);
          data += 64;
          datalen -= 512;
      }
  
      if (datalen > 0) {
          memcpy((void *) (S->buf + left), (void *) data, datalen >> 3);
          S->buflen = (left << 3) + datalen;
      } else {
          S->buflen = 0;
      }
  }
  
  // datalen = number of bits
  void blake224_update(state *S, const uint8_t *data, uint64_t datalen) {
      blake256_update(S, data, datalen);
  }
  
  void blake256_final_h(state *S, uint8_t *digest, uint8_t pa, uint8_t pb) {
      uint8_t msglen[8];
      uint32_t lo = S->t[0] + S->buflen, hi = S->t[1];
      if (lo < (unsigned) S->buflen) hi++;
      U32TO8(msglen + 0, hi);
      U32TO8(msglen + 4, lo);
  
      if (S->buflen == 440) { /* one padding byte */
          S->t[0] -= 8;
          blake256_update(S, &pa, 8);
      } else {
          if (S->buflen < 440) { /* enough space to fill the block  */
              if (S->buflen == 0) S->nullt = 1;
              S->t[0] -= 440 - S->buflen;
              blake256_update(S, padding, 440 - S->buflen);
          } else { /* need 2 compressions */
              S->t[0] -= 512 - S->buflen;
              blake256_update(S, padding, 512 - S->buflen);
              S->t[0] -= 440;
              blake256_update(S, padding + 1, 440);
              S->nullt = 1;
          }
          blake256_update(S, &pb, 8);
          S->t[0] -= 8;
      }
      S->t[0] -= 64;
      blake256_update(S, msglen, 64);
  
      U32TO8(digest +  0, S->h[0]);
      U32TO8(digest +  4, S->h[1]);
      U32TO8(digest +  8, S->h[2]);
      U32TO8(digest + 12, S->h[3]);
      U32TO8(digest + 16, S->h[4]);
      U32TO8(digest + 20, S->h[5]);
      U32TO8(digest + 24, S->h[6]);
      U32TO8(digest + 28, S->h[7]);
  }
  
  void blake256_final(state *S, uint8_t *digest) {
      blake256_final_h(S, digest, 0x81, 0x01);
  }
  
  void blake224_final(state *S, uint8_t *digest) {
      blake256_final_h(S, digest, 0x80, 0x00);
  }
  
  // inlen = number of bytes
  void blake256_hash(uint8_t *out, const uint8_t *in, uint64_t inlen) {
      state S;
      blake256_init(&S);
      blake256_update(&S, in, inlen * 8);
      blake256_final(&S, out);
  }
  
  // inlen = number of bytes
  void blake224_hash(uint8_t *out, const uint8_t *in, uint64_t inlen) {
      state S;
      blake224_init(&S);
      blake224_update(&S, in, inlen * 8);
      blake224_final(&S, out);
  }
  
  // keylen = number of bytes
  void hmac_blake256_init(hmac_state *S, const uint8_t *_key, uint64_t keylen) {
      const uint8_t *key = _key;
      uint8_t keyhash[32];
      uint8_t pad[64];
      uint64_t i;
  
      if (keylen > 64) {
          blake256_hash(keyhash, key, keylen);
          key = keyhash;
          keylen = 32;
      }
  
      blake256_init(&S->inner);
      memset(pad, 0x36, 64);
      for (i = 0; i < keylen; ++i) {
          pad[i] ^= key[i];
      }
      blake256_update(&S->inner, pad, 512);
  
      blake256_init(&S->outer);
      memset(pad, 0x5c, 64);
      for (i = 0; i < keylen; ++i) {
          pad[i] ^= key[i];
      }
      blake256_update(&S->outer, pad, 512);
  
      memwipe(keyhash, sizeof(keyhash));
  }
  
  // keylen = number of bytes
  void hmac_blake224_init(hmac_state *S, const uint8_t *_key, uint64_t keylen) {
      const uint8_t *key = _key;
      uint8_t keyhash[32];
      uint8_t pad[64];
      uint64_t i;
  
      if (keylen > 64) {
          blake256_hash(keyhash, key, keylen);
          key = keyhash;
          keylen = 28;
      }
  
      blake224_init(&S->inner);
      memset(pad, 0x36, 64);
      for (i = 0; i < keylen; ++i) {
          pad[i] ^= key[i];
      }
      blake224_update(&S->inner, pad, 512);
  
      blake224_init(&S->outer);
      memset(pad, 0x5c, 64);
      for (i = 0; i < keylen; ++i) {
          pad[i] ^= key[i];
      }
      blake224_update(&S->outer, pad, 512);
  
      memwipe(keyhash, sizeof(keyhash));
  }
  
  // datalen = number of bits
  void hmac_blake256_update(hmac_state *S, const uint8_t *data, uint64_t datalen) {
    // update the inner state
    blake256_update(&S->inner, data, datalen);
  }
  
  // datalen = number of bits
  void hmac_blake224_update(hmac_state *S, const uint8_t *data, uint64_t datalen) {
    // update the inner state
    blake224_update(&S->inner, data, datalen);
  }
  
  void hmac_blake256_final(hmac_state *S, uint8_t *digest) {
      uint8_t ihash[32];
      blake256_final(&S->inner, ihash);
      blake256_update(&S->outer, ihash, 256);
      blake256_final(&S->outer, digest);
      memwipe(ihash, sizeof(ihash));
  }
  
  void hmac_blake224_final(hmac_state *S, uint8_t *digest) {
      uint8_t ihash[32];
      blake224_final(&S->inner, ihash);
      blake224_update(&S->outer, ihash, 224);
      blake224_final(&S->outer, digest);
      memwipe(ihash, sizeof(ihash));
  }
  
  // keylen = number of bytes; inlen = number of bytes
  void hmac_blake256_hash(uint8_t *out, const uint8_t *key, uint64_t keylen, const uint8_t *in, uint64_t inlen) {
      hmac_state S;
      hmac_blake256_init(&S, key, keylen);
      hmac_blake256_update(&S, in, inlen * 8);
      hmac_blake256_final(&S, out);
  }
  
  // keylen = number of bytes; inlen = number of bytes
  void hmac_blake224_hash(uint8_t *out, const uint8_t *key, uint64_t keylen, const uint8_t *in, uint64_t inlen) {
      hmac_state S;
      hmac_blake224_init(&S, key, keylen);
      hmac_blake224_update(&S, in, inlen * 8);
      hmac_blake224_final(&S, out);
  }
  