SHA256
Computes the SHA256 hash for the input data.
/*****Please include following header files*****/
// stdio.h
// stdlib.h
// string.h
/***********************************************/
#define uchar unsigned char
#define uint unsigned int
#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 {
uchar data[64];
uint datalen;
uint bitlen[2];
uint state[8];
} SHA256_CTX;
uint 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
};
void SHA256Transform(SHA256_CTX *ctx, uchar data[])
{
uint 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;
}
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;
}
void SHA256Update(SHA256_CTX *ctx, uchar data[], uint len)
{
for (uint 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;
}
}
}
void SHA256Final(SHA256_CTX *ctx, uchar hash[])
{
uint 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);
memset(ctx->data, 0, 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;
}
}
char* SHA256(char* data) {
int strLen = strlen(data);
SHA256_CTX ctx;
unsigned char hash[32];
char* hashStr = malloc(65);
strcpy(hashStr, "");
SHA256Init(&ctx);
SHA256Update(&ctx, data, strLen);
SHA256Final(&ctx, hash);
char s[3];
for (int i = 0; i < 32; i++) {
sprintf(s, "%02x", hash[i]);
strcat(hashStr, s);
}
return hashStr;
}
Example
char data[] = "Hello World!";
char* sha256 = SHA256(data);
Output
7f83b1657ff1fc53b92dc18148a1d65dfc2d4b1fa3d677284addd200126d9069