Correctly hashing a string in C - c

Question

When using the terminal utility "openssl" with the following command:
echo -n "Hello World!" | openssl sha1
This is the output produced:
(stdin)= 2ef7bde608ce5404e97d5f042f95f89f1c232871
I've tried producing the same output with following C code:
#include <stdio.h>
#include <stdlib.h>
#include <openssl/sha.h>
int main(void){
const unsigned char source_string[1024] = "Hello World!";
unsigned char dest_string[1024];
SHA1(source_string, 16, dest_string);
printf("String: %s\nHashed string: %s\n", source_string, dest_string);
return 0;
}
However, it produces this weird non-unicode output:
String: Hello World!
Hashed string: #�V�#��#�����T\�
How can I make it produce the same output as the before shown openssl terminal command?

Answer 1

You should
Pass the correct length of the string (it is 12-byte long) to SHA1.
Print the result in hexadecimal, not as string.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/sha.h>
int main(void){
const unsigned char source_string[1024] = "Hello World!";
unsigned char dest_string[1024];
int i;
SHA1(source_string, strlen((const char*)source_string), dest_string);
printf("String: %s\nHashed string: ", source_string);
for (i = 0; i < 20; i++) printf("%02x", dest_string[i]);
putchar('\n');
return 0;
}
I didn't check by running this, so there may be other errors.