text: #include <stdio.h>
  #include <stdlib.h>
  #include <sha2.h>
  
  unsigned char app_b1[SHA256_DIGEST_LENGTH] = {
      0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
      0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
      0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
      0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad
  };
  
  unsigned char app_b2[SHA256_DIGEST_LENGTH] = {
      0xcd, 0xc7, 0x6e, 0x5c, 0x99, 0x14, 0xfb, 0x92,
      0x81, 0xa1, 0xc7, 0xe2, 0x84, 0xd7, 0x3e, 0x67,
      0xf1, 0x80, 0x9a, 0x48, 0xa4, 0x97, 0x20, 0x0e,
      0x04, 0x6d, 0x39, 0xcc, 0xc7, 0x11, 0x2c, 0xd0
  };
  
  int main(int argc, char **argv)
  {
  	unsigned char md[SHA256_DIGEST_LENGTH];
  
  	fprintf(stdout, "Testing SHA-256 ");
  	SHA256_CTX *state = malloc(sizeof(SHA256_CTX));
  	SHA256_Init(state);
  
  	SHA256_Update(state, "abc", 3);
  	SHA256_Final(md, state);
  	if (memcmp(md, app_b1, sizeof(app_b1))) {
  		fflush(stdout);
  		fprintf(stderr, "\nTEST 1 of 2 failed.\n");
  		return 1;
      } else
  		fprintf(stdout, ".");
  	fflush(stdout);
  
  	SHA256_Init(state);
  	int i;
  	for (i = 0; i < 1000000; i += 160)
  		SHA256_Update(state, "aaaaaaaa" "aaaaaaaa" "aaaaaaaa" "aaaaaaaa"
  		                     "aaaaaaaa" "aaaaaaaa" "aaaaaaaa" "aaaaaaaa"
  		                     "aaaaaaaa" "aaaaaaaa" "aaaaaaaa" "aaaaaaaa"
  		                     "aaaaaaaa" "aaaaaaaa" "aaaaaaaa" "aaaaaaaa"
  		                     "aaaaaaaa" "aaaaaaaa" "aaaaaaaa" "aaaaaaaa",
  		                     (1000000 - i) < 160 ? 1000000 - i : 160);
  	SHA256_Final(md, state);
  
  	if (memcmp(md, app_b2, sizeof(app_b2))) {
  		fflush(stdout);
  		fprintf(stderr, "\nTEST 2 of 2 failed.\n");
  		return 1;
      } else
  		fprintf(stdout, ".");
  
  	free(state);
  	fprintf(stdout, " passed.\n");
  	fflush(stdout);
  
  	return 0;
  } 
  