sha256.c

/*
 * SHA256
 *
 * The author (Brad Conte) has released this file "into the public domain free
 * of any restrictions".  This file is unchanged except for some style
 * clean-up.
 */

#define DBL_INT_ADD(a, b, c) if (a > 0xffffffff - (c)) ++b; a += c;
#define ROTLEFT(a, b) (((a) << (b)) | ((a) >> (32-(b))))
#define ROTRIGHT(a, b) (((a) >> (b)) | ((a) << (32-(b))))

#define CH(x, y, z) (((x) & (y)) ^ (~(x) & (z)))
#define MAJ(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define EP0(x) (ROTRIGHT(x, 2) ^ ROTRIGHT(x, 13) ^ ROTRIGHT(x, 22))
#define EP1(x) (ROTRIGHT(x, 6) ^ ROTRIGHT(x, 11) ^ ROTRIGHT(x, 25))
#define SIG0(x) (ROTRIGHT(x, 7) ^ ROTRIGHT(x, 18) ^ ((x) >> 3))
#define SIG1(x) (ROTRIGHT(x, 17) ^ ROTRIGHT(x, 19) ^ ((x) >> 10))

typedef struct _SHA256_CTX
{
    UINT8 data[64];
    UINT32 datalen;
    UINT32 bitlen[2];
    UINT32 state[8];
} SHA256_CTX;

static const UINT32 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 sha256Transform(SHA256_CTX *ctx, UINT8 *data)
{  
    UINT32 a, b, c, d, e, f, g, h, i, j, t1, t2, m[64];
      
    for (i = 0, j = 0; i < 16; ++i, j += 4)
        m[i] = (data[j] << 24) | (data[j+1] << 16) | (data[j+2] << 8) |
            (data[j+3]);
    for (; i < 64; ++i)
        m[i] = SIG1(m[i-2]) + m[i-7] + SIG0(m[i-15]) + m[i-16];

    a = ctx->state[0];
    b = ctx->state[1];
    c = ctx->state[2];
    d = ctx->state[3];
    e = ctx->state[4];
    f = ctx->state[5];
    g = ctx->state[6];
    h = ctx->state[7];
   
    for (i = 0; i < 64; ++i)
    {
        t1 = h + EP1(e) + CH(e, f, g) + k[i] + m[i];
        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;
    }
   
    ctx->state[0] += a;
    ctx->state[1] += b;
    ctx->state[2] += c;
    ctx->state[3] += d;
    ctx->state[4] += e;
    ctx->state[5] += f;
    ctx->state[6] += g;
    ctx->state[7] += h;
}

static void sha256Init(SHA256_CTX *ctx)
{  
    ctx->datalen = 0; 
    ctx->bitlen[0] = 0; 
    ctx->bitlen[1] = 0; 
    ctx->state[0] = 0x6a09e667;
    ctx->state[1] = 0xbb67ae85;
    ctx->state[2] = 0x3c6ef372;
    ctx->state[3] = 0xa54ff53a;
    ctx->state[4] = 0x510e527f;
    ctx->state[5] = 0x9b05688c;
    ctx->state[6] = 0x1f83d9ab;
    ctx->state[7] = 0x5be0cd19;
}

static void sha256Update(SHA256_CTX *ctx, UINT8 *data, UINT32 len)
{  
    UINT32 i;
   
    for (i = 0; i < len; ++i)
    { 
        ctx->data[ctx->datalen] = data[i]; 
        ctx->datalen++; 
        if (ctx->datalen == 64)
        { 
            sha256Transform(ctx, ctx->data);
            DBL_INT_ADD(ctx->bitlen[0], ctx->bitlen[1], 512); 
            ctx->datalen = 0; 
        }  
    }  
}  

static void sha256Final(SHA256_CTX *ctx, UINT8 *hash)
{  
    UINT32 i; 
   
    i = ctx->datalen; 
    if (ctx->datalen < 56)
    { 
        ctx->data[i++] = 0x80; 
        while (i < 56) 
            ctx->data[i++] = 0x00; 
    }
    else
    { 
        ctx->data[i++] = 0x80; 
        while (i < 64) 
            ctx->data[i++] = 0x00; 
        sha256Transform(ctx, ctx->data);
        ZeroMemory(ctx->data, 56); 
    }  
   
    DBL_INT_ADD(ctx->bitlen[0], ctx->bitlen[1], ctx->datalen * 8);
    ctx->data[63] = ctx->bitlen[0]; 
    ctx->data[62] = ctx->bitlen[0] >> 8; 
    ctx->data[61] = ctx->bitlen[0] >> 16; 
    ctx->data[60] = ctx->bitlen[0] >> 24; 
    ctx->data[59] = ctx->bitlen[1]; 
    ctx->data[58] = ctx->bitlen[1] >> 8; 
    ctx->data[57] = ctx->bitlen[1] >> 16;  
    ctx->data[56] = ctx->bitlen[1] >> 24; 
    sha256Transform(ctx, ctx->data);
   
    for (i = 0; i < 4; ++i)
    { 
        hash[i]    = (ctx->state[0] >> (24-i*8)) & 0x000000ff; 
        hash[i+4]  = (ctx->state[1] >> (24-i*8)) & 0x000000ff; 
        hash[i+8]  = (ctx->state[2] >> (24-i*8)) & 0x000000ff;
        hash[i+12] = (ctx->state[3] >> (24-i*8)) & 0x000000ff;
        hash[i+16] = (ctx->state[4] >> (24-i*8)) & 0x000000ff;
        hash[i+20] = (ctx->state[5] >> (24-i*8)) & 0x000000ff;
        hash[i+24] = (ctx->state[6] >> (24-i*8)) & 0x000000ff;
        hash[i+28] = (ctx->state[7] >> (24-i*8)) & 0x000000ff;
   }
}