static void digestNtoStr(const unsigned char digest[], int n, char *output)
{
    int i;
    for (i = 0; i<n; ++i) {
        pj_val_to_hex_digit(digest[i], output);
        output += 2;
    }
}
static void digestNtoStr(const unsigned char digest[], int n, char *output)
{
    int i;
    for (i = 0; i<n; ++i) {
        pj_val_to_hex_digit(digest[i], output);
        output += 2;
    }
}