diff --git a/ChangeLog b/ChangeLog
index 3e9e55e39..d902bd62f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,7 @@
      [deattack.c]
      so that large packets do not wrap "n"; from netbsd
  - (bal) rijndel.c - fix up RCSID to match OpenBSD tree
+ - (bal) auth2-skey.c - Checked in.  Missing from portable tree
 
 20001029
  - (stevesk) Fix typo in auth.c: USE_PAM not PAM
diff --git a/Makefile.in b/Makefile.in
index 03c745914..c55352635 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -41,7 +41,7 @@ LIBOPENBSD_COMPAT_OBJS=bsd-arc4random.o bsd-base64.o bsd-bindresvport.o bsd-daem
 
 SSHOBJS= ssh.o sshconnect.o sshconnect1.o sshconnect2.o log-client.o readconf.o clientloop.o
 
-SSHDOBJS= sshd.o auth.o auth1.o auth2.o auth-rhosts.o auth-options.o auth-krb4.o auth-pam.o auth-passwd.o auth-rsa.o auth-rh-rsa.o dh.o pty.o log-server.o login.o loginrec.o servconf.o serverloop.o md5crypt.o session.o
+SSHDOBJS= sshd.o auth.o auth1.o auth2.o auth2-skey.o auth-rhosts.o auth-options.o auth-krb4.o auth-pam.o auth-passwd.o auth-rsa.o auth-rh-rsa.o dh.o pty.o log-server.o login.o loginrec.o servconf.o serverloop.o md5crypt.o session.o
 
 TROFFMAN	= scp.1 ssh-add.1 ssh-agent.1 ssh-keygen.1 ssh.1 sshd.8 sftp-server.8
 CATMAN		= scp.0 ssh-add.0 ssh-agent.0 ssh-keygen.0 ssh.0 sshd.0 sftp-server.0
diff --git a/auth2-skey.c b/auth2-skey.c
new file mode 100644
index 000000000..e29205d4b
--- /dev/null
+++ b/auth2-skey.c
@@ -0,0 +1,107 @@
+#include "includes.h"
+RCSID("$OpenBSD: auth2-skey.c,v 1.1 2000/10/11 20:14:38 markus Exp $");
+
+#ifdef SKEY
+#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, int echo);
+void	input_userauth_info_response(int type, int plen, void *ctxt);
+
+/*
+ * try skey authentication, always return -1 (= postponed) since we have to
+ * wait for the s/key response.
+ */
+int
+auth2_skey(Authctxt *authctxt)
+{
+	send_userauth_into_request(authctxt, 0);
+	dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, &input_userauth_info_response);
+	return -1;
+}
+
+void
+send_userauth_into_request(Authctxt *authctxt, int echo)
+{
+	int retval = -1;
+	struct skey skey;
+	char challenge[SKEY_MAX_CHALLENGE];
+	char *fake;
+
+	if (authctxt->user == NULL)
+		fatal("send_userauth_into_request: internal error: no user");
+
+	/* get skey challenge */
+	if (authctxt->valid)
+		retval = skeychallenge(&skey, authctxt->user, challenge);
+
+	if (retval == -1) {
+		fake = skey_fake_keyinfo(authctxt->user);
+		strlcpy(challenge, fake, sizeof challenge);
+	}
+	/* send our info request */
+	packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
+	packet_put_cstring("S/Key Authentication");	/* Name */
+	packet_put_cstring(challenge);			/* Instruction */
+	packet_put_cstring("");				/* Language */
+	packet_put_int(1);			 	/* Number of prompts */
+	packet_put_cstring(echo ?
+		 "Response [Echo]: ": "Response: ");	/* Prompt */
+	packet_put_char(echo);				/* Echo */
+	packet_send();
+	packet_write_wait();
+	memset(challenge, 'c', sizeof challenge);
+}
+
+void
+input_userauth_info_response(int type, int plen, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	int authenticated = 0;
+	unsigned int nresp, rlen;
+	char *resp, *method;
+
+	if (authctxt == NULL)
+		fatal("input_userauth_info_response: no authentication context");
+
+	if (authctxt->attempt++ >= AUTH_FAIL_MAX)
+		packet_disconnect("too many failed userauth_requests");
+
+	nresp = packet_get_int();
+	if (nresp == 1) {
+		/* we only support s/key and assume s/key for nresp == 1 */
+		method = "s/key";
+		resp = packet_get_string(&rlen);
+		packet_done();
+		if (strlen(resp) == 0) {
+			/*
+			 * if we received a null response, resend prompt with
+			 * echo enabled
+			 */
+			authenticated = -1;
+			userauth_log(authctxt, authenticated, method);
+			send_userauth_into_request(authctxt, 1);
+		} else {
+			/* verify skey response */
+			if (authctxt->valid &&
+			    skey_haskey(authctxt->pw->pw_name) == 0 &&
+			    skey_passcheck(authctxt->pw->pw_name, resp) != -1) {
+				authenticated = 1;
+			} else {
+				authenticated = 0;
+			}
+			memset(resp, 'r', rlen);
+			/* unregister callback */
+			dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
+			userauth_log(authctxt, authenticated, method);
+			userauth_reply(authctxt, authenticated);
+		}
+		xfree(resp);
+	}
+}
+
+#endif /* SKEY */