30th June 2013, 1 min read

Very simple SHA1 test program written in C

Original post is here eklausmeier.goip.de/blog/2013/06-30-very-simple-sha1-test-program-written-in-c.

Here is a simple test program to call SHA1 hashing routine from OpenSSL.

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

int main (int argc, char *argv[]) {
        unsigned long i, n;
        unsigned char md[1024];

        if (argc <= 1) return 0;

        n = strlen(argv[1]);
        SHA1((unsigned char*)argv[1],n,md);

        for (i=0; i<SHA_DIGEST_LENGTH; ++i)
                printf("%02x",md[i]);
        puts("");

        return 0;
}

Compile with

cc -Wall sha1tst.c -o sha1tst -lcrypto

It is important to give the -l flag after -o.

Some tests:

$ ./sha1tst ABCabc
135488ccc0c5e5a3d0ac437aac1821bba9347b3d
$ printf "ABCabc" | sha1sum
135488ccc0c5e5a3d0ac437aac1821bba9347b3d  -

In Ubuntu the openssl development libraries are in libssl-dev.