sha2.c

#include "sha2.h"
#include <string.h>
#include <stdint.h>

#define ROR(x,n) (((x)>>(n))|((x)<<(32-(n))))
#define SIG0(x) (ROR(x,7) ^ ROR(x,18) ^ ((x) >> 3))
#define SIG1(x) (ROR(x,17) ^ ROR(x,19) ^ ((x) >> 10))
#define EP0(x) (ROR(x,2) ^ ROR(x,13) ^ ROR(x,22))
#define EP1(x) (ROR(x,6) ^ ROR(x,11) ^ ROR(x,25))
#define CH(x,y,z)  (((x) & (y)) ^ (~(x) & (z)))
#define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define LOAD32_BE(p) \
  (((uint32_t)(p)[0] << 24) | \
   ((uint32_t)(p)[1] << 16) | \
   ((uint32_t)(p)[2] << 8)  | \
   ((uint32_t)(p)[3]))
#define STORE32_BE(p, v)       \
  do {                         \
    (p)[3] = (uint8_t)((v));   \
    (p)[2] = (uint8_t)((v) >> 8);  \
    (p)[1] = (uint8_t)((v) >> 16); \
    (p)[0] = (uint8_t)((v) >> 24); \
  } while (0)
#define STORE64_BE(p, v)       \
  do {                         \
    (p)[0] = (uint8_t)((v) >> 56); \
    (p)[1] = (uint8_t)((v) >> 48); \
    (p)[2] = (uint8_t)((v) >> 40); \
    (p)[3] = (uint8_t)((v) >> 32); \
    (p)[4] = (uint8_t)((v) >> 24); \
    (p)[5] = (uint8_t)((v) >> 16); \
    (p)[6] = (uint8_t)((v) >> 8);  \
    (p)[7] = (uint8_t)(v);         \
  } while (0)

typedef struct {
  uint64_t n;
  uint32_t h[8];
} sha2s;

static const uint32_t K[64] = {
  0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
  0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
  0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
  0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
  0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
  0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
  0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
  0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
  0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
  0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
  0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
  0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
  0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
  0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
};

static void sha2block(sha2s *s, const unsigned char *p) {
  int i;
  uint32_t w[64]={0};
  uint32_t a=s->h[0],b=s->h[1],c=s->h[2],d=s->h[3];
  uint32_t e=s->h[4],f=s->h[5],g=s->h[6],h=s->h[7];

  s->n++;

  for(i=0;i<16;i++) w[i] = LOAD32_BE(p+4*i);

  for(i=16;i<64;i++) w[i] = SIG1(w[i-2]) + w[i-7] + SIG0(w[i-15]) + w[i-16];

  for(i=0;i<64;i++) {
    uint32_t t1 = h + EP1(e) + CH(e,f,g) + K[i] + w[i];
    uint32_t t2 = EP0(a) + MAJ(a,b,c);
    h = g;
    g = f;
    f = e;
    e = d + t1;
    d = c;
    c = b;
    b = a;
    a = t1 + t2;
  }

  s->h[0] += a;
  s->h[1] += b;
  s->h[2] += c;
  s->h[3] += d;
  s->h[4] += e;
  s->h[5] += f;
  s->h[6] += g;
  s->h[7] += h;
}

static void sha2final(sha2s *s, unsigned char *p, size_t n, unsigned char *d) {
  uint32_t i,*h=s->h;
  uint64_t len=(s->n*64ULL+n)*8ULL;

  p[n++] = 0x80;
  if(n<=56) memset(p+n,0,56-n);
  else {
    memset(p+n,0,64-n);
    sha2block(s,p);
    memset(p,0,56);
  }

  STORE64_BE(p+56,len);
  sha2block(s,p);
  for(i=0;i<8;i++) STORE32_BE(d+4*i,h[i]);
}

static void hex(char *s, const unsigned char *b, size_t n) {
  const char h[]="0123456789abcdef";
  size_t i;
  for(i=0;i<n;i++) {
    s[2*i]=h[b[i]>>4];
    s[2*i+1]=h[b[i]&0xf];
  }
  s[2*i]=0;
}

void sha2(char *h, const unsigned char *b, size_t n) {
  unsigned char block[64]={0},d[32];
  sha2s s={0,{0x6a09e667,0xbb67ae85,0x3c6ef372,0xa54ff53a,
              0x510e527f,0x9b05688c,0x1f83d9ab,0x5be0cd19}};
  while(n>=64) {
    sha2block(&s,b);
    b+=64;
    n-=64;
  }
  memcpy((char*)block,(char*)b,n);
  sha2final(&s,block,n,d);
  hex(h,d,32);
}