diff --git a/auth2-chall.c b/auth2-chall.c
new file mode 100644
index 0000000..77294f4
--- /dev/null
+++ b/auth2-chall.c
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2001 Markus Friedl. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "includes.h"
+RCSID("$OpenBSD: auth2-chall.c,v 1.1 2001/01/18 17:12:43 markus Exp $");
+
+#include "ssh.h"
+#include "ssh2.h"
+#include "auth.h"
+#include "packet.h"
+#include "xmalloc.h"
+#include "dispatch.h"
+
+void send_userauth_into_request(Authctxt *authctxt, char *challenge, int echo);
+void input_userauth_info_response(int type, int plen, void *ctxt);
+
+/*
+ * try challenge-reponse, return -1 (= postponed) if we have to
+ * wait for the response.
+ */
+int
+auth2_challenge(Authctxt *authctxt, char *devs)
+{
+	char *challenge;
+
+	if (!authctxt->valid || authctxt->user == NULL)
+		return 0;
+	if ((challenge = get_challenge(authctxt, devs)) == NULL)
+		return 0;
+	send_userauth_into_request(authctxt, challenge, 0);
+	dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE,
+	    &input_userauth_info_response);
+	authctxt->postponed = 1;
+	return 0;
+}
+
+void
+send_userauth_into_request(Authctxt *authctxt, char *challenge, int echo)
+{
+	int nprompts = 1;
+
+	packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
+	/* name, instruction and language are unused */
+	packet_put_cstring("");
+	packet_put_cstring("");
+	packet_put_cstring("");
+	packet_put_int(nprompts);
+	packet_put_cstring(challenge);
+	packet_put_char(echo);
+	packet_send();
+	packet_write_wait();
+}
+
+void
+input_userauth_info_response(int type, int plen, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	int authenticated = 0;
+	u_int nresp, rlen;
+	char *response, *method = "challenge-reponse";
+
+	if (authctxt == NULL)
+		fatal("input_userauth_info_response: no authctxt");
+
+	authctxt->postponed = 0;	/* reset */
+	nresp = packet_get_int();
+	if (nresp == 1) {
+		response = packet_get_string(&rlen);
+		packet_done();
+		if (strlen(response) == 0) {
+			/*
+			 * if we received an empty response, resend challenge
+			 * with echo enabled
+			 */
+			char *challenge = get_challenge(authctxt, NULL);
+			if (challenge != NULL) {
+				send_userauth_into_request(authctxt,
+				    challenge, 1);
+				authctxt->postponed = 1;
+			}
+		} else if (authctxt->valid) {
+			authenticated = verify_response(authctxt, response);
+			memset(response, 'r', rlen);
+		}
+		xfree(response);
+	}
+	auth_log(authctxt, authenticated, method, " ssh2");
+	if (!authctxt->postponed) {
+		/* unregister callback and send reply */
+		dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
+		userauth_reply(authctxt, authenticated);
+	}
+}