Generate the Sha1 of a string using OpenSSL.

sha1.c

#include <stdio.h>
#include <string.h>
#include <openssl/sha.h>

// gcc -o sha1 sha1.c -lcrypto

int main(void) {
  const unsigned char ibuf[] = "compute sha1";
  unsigned char obuf[20];

  SHA1(ibuf, strlen(ibuf), obuf);

  int i;
  for (i = 0; i < 20; i++) {
    printf("%02x", obuf[i]);
  }
  printf("\n");

  return 0;
}