<dt><strong>-request </strong><em>bool</em></dt>
	<dd>Request a certificate from peer during SSL handshake.
	    (default is <em>true</em>)</dd>
	<dt><strong>-require</strong> <em>bool</em></dt>
	<dd>Require a valid certificate from peer during SSL handshake.
	    If this is set to true, then <strong>-request</strong> must
	    also be set to true. (default is <em>false</em>)</dd>
	<dt><strong>-security_level</strong> <em>integer</em></dt>
	<dd>Set security level. Must be 0 to 5. The security level affects
	    cipher suite encryption algorithms, supported ECC curves,
	    supported signature algorithms, DH parameter sizes, certificate
	    key sizes and signature algorithms. The default is 1.
	    Level 3 and higher disable support for session tickets and only
	    accept cipher suites that provide forward secrecy.</dd>
	<dt><strong>-server</strong> <em>bool</em></dt>

	OPTBYTE("-key", key, key_len);
	OPTSTR("-keyfile", keyfile);
	OPTSTR("-model", model);
	OPTOBJ("-password", password);
	OPTBOOL("-post_handshake", post_handshake);
	OPTBOOL("-request", request);
	OPTBOOL("-require", require);
	OPTINT("-security_level", level);
	OPTBOOL("-server", server);
	OPTSTR("-servername", servername);
	OPTSTR("-session_id", session_id);
	OPTBOOL("-ssl2", ssl2);
	OPTBOOL("-ssl3", ssl3);
	OPTBOOL("-tls1", tls1);
	OPTBOOL("-tls1.1", tls1_1);
	OPTBOOL("-tls1.2", tls1_2);
	OPTBOOL("-tls1.3", tls1_3);
	OPTOBJ("-validatecommand", vcmd);
	OPTOBJ("-vcmd", vcmd);

	OPTBAD("option", "-alpn, -cadir, -cafile, -cert, -certfile, -cipher, -ciphersuites, -command, -dhparams, -key, -keyfile, -model, -password, -post_handshake, -request, -require, -security_level, -server, -servername, -session_id, -ssl2, -ssl3, -tls1, -tls1.1, -tls1.2, -tls1.3, or -validatecommand");

	return TCL_ERROR;
    }
    if (request)		verify |= SSL_VERIFY_CLIENT_ONCE | SSL_VERIFY_PEER;
    if (request && require)	verify |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
    if (request && post_handshake)	verify |= SSL_VERIFY_POST_HANDSHAKE;
    if (verify == 0)		verify = SSL_VERIFY_NONE;

    }
#endif

    /* Force cipher selection order by server */
    if (!isServer) {
	SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
    }

#if OPENSSL_VERSION_NUMBER < 0x10100000L
    OpenSSL_add_all_algorithms(); /* Load ciphers and digests */
#endif

    SSL_CTX_set_app_data(ctx, (void*)interp);	/* remember the interpreter */
    SSL_CTX_set_options(ctx, SSL_OP_ALL);	/* all SSL bug workarounds */
    SSL_CTX_set_options(ctx, SSL_OP_NO_COMPRESSION);	/* disable compression even if supported */
    SSL_CTX_set_options(ctx, off);		/* disable protocol versions */
#if OPENSSL_VERSION_NUMBER < 0x10101000L
    SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);	/* handle new handshakes in background. On by default in OpenSSL 1.1.1. */

	/* Get protocol */
	LAPPEND_STR(interp, objPtr, "protocol", SSL_get_version(ssl), -1);

	/* Renegotiation allowed */
	LAPPEND_BOOL(interp, objPtr, "renegotiation_allowed", SSL_get_secure_renegotiation_support(ssl));

	/* Get security level */
	LAPPEND_INT(interp, objPtr, "security_level", SSL_get_security_level(ssl));

	/* Session info */
	LAPPEND_BOOL(interp, objPtr, "session_reused", SSL_session_reused(ssl));

	/* Is server info */
	LAPPEND_BOOL(interp, objPtr, "is_server", SSL_is_server(ssl));

/* Define maximum certificate size. Max PEM size 100kB and DER size is 24kB. */
#define CERT_STR_SIZE 32768


/*
 * Binary string to hex string
 */
int String_to_Hex(unsigned char* input, int ilen, unsigned char *output, int olen) {
    int count = 0;
    unsigned char *iptr = input;
    unsigned char *optr = &output[0];
    const char *hex = "0123456789abcdef";

    for (int i = 0; i < ilen && count < olen - 1; i++, count += 2) {

        *optr++ = hex[(*iptr>>4)&0xF];
        *optr++ = hex[(*iptr++)&0xF];
    }
    *optr = 0;
    return count;
}

/*
 * BIO to Buffer
 */
int BIO_to_Buffer(int result, BIO *bio, void *buffer, int size) {