Secret Key Store/Load Testing 123...

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <stdint.h>


#if defined (NDEBUG)
#   error Not ready for NDEBUG to be defined!
#endif


void ct_hex_printf(
    FILE* fout,
    unsigned char* buf,
    size_t buf_sz
) {
    for (size_t i = 0; i < buf_sz; i++)
    {
        fprintf(fout, "%02x ", buf[i]);
    }
}


int
ct_secret_key_store_test(void)
{
    //int status = 0; // assume failed status... ;^)

    FILE* file = fopen("sk.bin", "wb");
    assert(file);

    printf(
        "ct_secret_key_store_test\n"
        "____________________________________\n"
    );

    if (file)
    {
        #define HMAC_ALGO_SZ (32 + 1)

        char hmac_algo[] = "sha256";
        unsigned long hmac_algo_sz = sizeof(hmac_algo) - 1;


        char hmac_key[] = "Password";
        unsigned long hmac_key_sz = sizeof(hmac_key) - 1;


        unsigned long rand_n = 32;


        fprintf(file, "%lu,%lu,%lu,", hmac_algo_sz, hmac_key_sz, rand_n);
        fwrite(hmac_algo, 1, hmac_algo_sz, file);
        fwrite(hmac_key, 1, hmac_key_sz, file);


        fprintf(
            stdout,
            "%lu,%lu,%lu,%s%s",
            hmac_algo_sz,
            hmac_key_sz,
            rand_n,
            hmac_algo,
            hmac_key
        );
    }

    fclose(file);

    printf(
        "\n____________________________________\n\n\n"
    );

    return 1;
}


int
ct_secret_key_load_test(void)
{
    int status = 0; // assume failed status... ;^)

    FILE* file = fopen("sk.bin", "rb");
    assert(file);

    printf(
        "ct_secret_key_load_test\n"
        "____________________________________\n"
    );

    if (file)
    {
        unsigned long hmac_algo_sz = 0;
        unsigned long hmac_key_sz = 0;
        unsigned long rand_n = 0;

        status = fscanf(
            file,
            "%lu,%lu,%lu,",
            &hmac_algo_sz,
            &hmac_key_sz,
            &rand_n
        );



        assert(status == 3);

        if (status == 3)
        {
            size_t buf_sz = hmac_algo_sz + hmac_key_sz;
            unsigned char* buf = calloc(1, buf_sz); // calloc and peformance?
            assert(buf);

            if (buf)
            {
                status = fread(buf, 1, hmac_algo_sz, file);
                assert((size_t)status == hmac_algo_sz);


                fprintf(
                    stdout,
                    "%lu,%lu,%lu,",
                    hmac_algo_sz,
                    hmac_key_sz,
                    rand_n
                );

                printf("[");
                ct_hex_printf(stdout, buf, hmac_algo_sz);
                printf("]");

                if ((size_t)status == hmac_algo_sz)
                {
                    status = fread(buf + hmac_algo_sz, 1, hmac_key_sz, file);
                    assert((size_t)status == hmac_key_sz);

                    if ((size_t)status == hmac_key_sz)
                    {
                        // okay: we are one...
                        printf("[");
                        ct_hex_printf(stdout, buf + hmac_algo_sz, hmac_key_sz);
                        printf("]");

                        status = 1;
                    }
                }

                free(buf);
            }
        }
    }

    fclose(file);

    printf(
        "\n____________________________________\n\n\n"
    );

    return status;
}


int main(void)
{
    {
        int status_store = ct_secret_key_store_test();
        assert(status_store == 1);


        int status_load = ct_secret_key_load_test();
        assert(status_load == 1);
    }

    return 0;
}