diff -u ssh-1.2.27.orig/cipher.c ssh-1.2.27/cipher.c
--- ssh-1.2.27.orig/cipher.c	Tue Jul 20 00:40:16 1999
+++ ssh-1.2.27/cipher.c	Tue Jul 20 00:47:07 1999
@@ -69,11 +69,22 @@
 #include "ssh.h"
 #include "cipher.h"
 
+#ifdef WITH_ROT13
+void rot13cpy(char *dest,char *src,unsigned len) {
+  while(len--) {
+    if((*src>='a')&&(*src<='m')) *dest=(*src)+13;
+    else if((*src>='n')&&(*src<='z')) *dest=(*src)-13;
+    else if((*src>='A')&&(*src<='M')) *dest=(*src)+13;
+    else if((*src>='N')&&(*src<='Z')) *dest=(*src)-13;
+    else *dest=*src;
+    dest++, src++; }; }
+#endif
+
 /* Names of all encryption algorithms.  These must match the numbers defined
    int cipher.h. */
 static char *cipher_names[] =
 { "none", "idea", "des", "3des", "used to be tss", "arcfour", "blowfish",
-  "reserved"};
+  "reserved", "rot13"};
 
 /* Returns a bit mask indicating which ciphers are supported by this
    implementation.  The bit mask has the corresponding bit set of each
@@ -104,6 +115,10 @@
 #ifdef WITH_BLOWFISH
   mask |= 1 << SSH_CIPHER_BLOWFISH;
 #endif /* WITH_BLOWFISH */
+
+#ifdef WITH_ROT13
+  mask |= 1 << SSH_CIPHER_ROT13;
+#endif /* WITH_ROT13 */
   return mask;
 }
 
@@ -248,6 +263,12 @@
       blowfish_set_key(&context->u.blowfish, key, keylen, for_encryption);
       break;
 #endif /* WITH_BLOWFISH */
+
+#ifdef WITH_ROT13
+    case SSH_CIPHER_ROT13:
+      break;
+#endif /* WITH_ROT13 */
+
     default:
       fatal("cipher_set_key: unknown cipher: %d", cipher);
     }
@@ -297,6 +318,12 @@
       break;
 #endif /* WITH_BLOWFISH */
       
+#ifdef WITH_ROT13
+    case SSH_CIPHER_ROT13:
+      rot13cpy(dest,src,len);
+      break;
+#endif /* WITH_ROT13 */
+
     default:
       fatal("cipher_encrypt: unknown cipher: %d", context->type);
     }
@@ -345,6 +372,12 @@
       break;
 #endif /* WITH_BLOWFISH */
       
+#ifdef WITH_ROT13
+    case SSH_CIPHER_ROT13:
+      rot13cpy(dest,src,len);
+      break;
+#endif /* WITH_ROT13 */
+
     default:
       fatal("cipher_decrypt: unknown cipher: %d", context->type);
     }
diff -u ssh-1.2.27.orig/cipher.h ssh-1.2.27/cipher.h
--- ssh-1.2.27.orig/cipher.h	Tue Jul 20 00:40:50 1999
+++ ssh-1.2.27/cipher.h	Tue Jul 20 00:47:44 1999
@@ -77,6 +77,7 @@
 #define SSH_CIPHER_BLOWFISH     6 /* Bruce Schneier's Blowfish */
 #define SSH_CIPHER_RESERVED	7 /* Reserved for 40 bit crippled encryption,
 				     Bernard Perrot <perrot@lal.in2p3.fr> */
+#define SSH_CIPHER_ROT13        8 /* ROT13 */
 
 typedef struct {
   unsigned int type;
diff -u ssh-1.2.27.orig/config.h.in ssh-1.2.27/config.h.in
--- ssh-1.2.27.orig/config.h.in	Tue Jul 20 00:40:59 1999
+++ ssh-1.2.27/config.h.in	Tue Jul 20 00:48:05 1999
@@ -165,6 +165,7 @@
 #undef WITH_ARCFOUR
 #undef WITH_BLOWFISH
 #undef WITH_NONE
+#undef WITH_ROT13
 
 /* Define this to include libwrap (tcp_wrappers) support. */
 #undef LIBWRAP
diff -u ssh-1.2.27.orig/configure.in ssh-1.2.27/configure.in
--- ssh-1.2.27.orig/configure.in	Tue Jul 20 00:41:23 1999
+++ ssh-1.2.27/configure.in	Tue Jul 20 00:51:11 1999
@@ -732,6 +732,22 @@
   AC_MSG_RESULT(no)
 )
 
+AC_MSG_CHECKING(whether to include the ROT13 encryption algorithm)
+AC_ARG_WITH(rot13,
+[  --with-rot13            Include ROT13 (Do NOT enable this, it is worthless)
+  --without-rot13         Don't include ROT13 (default)],
+[ case $withval in
+  yes)
+   AC_MSG_RESULT(yes)
+   AC_DEFINE(WITH_ROT13)
+   ;;
+  *)
+   AC_MSG_RESULT(no)
+   ;;
+  esac ],
+  AC_MSG_RESULT(no)
+)
+
 AC_MSG_CHECKING(whether to include the none encryption algorithm)
 AC_ARG_WITH(none,
 [  --with-none             Include support for unencrypted connections
diff -u ssh-1.2.27.orig/ssh.c ssh-1.2.27/ssh.c
--- ssh-1.2.27.orig/ssh.c	Tue Jul 20 00:41:30 1999
+++ ssh-1.2.27/ssh.c	Tue Jul 20 00:51:47 1999
@@ -309,6 +309,9 @@
 #ifdef WITH_BLOWFISH
           "``blowfish'', "
 #endif /* WITH_BLOWFISH */
+#ifdef WITH_ROT13
+	  "``rot13'', "
+#endif /* WITH_ROT13 */
           "``3des''\n");
   fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
   fprintf(stderr, "  -P          Don't use privileged source port.\n");
diff -u ssh-1.2.27.orig/sshd.c ssh-1.2.27/sshd.c
--- ssh-1.2.27.orig/sshd.c	Tue Jul 20 00:41:33 1999
+++ ssh-1.2.27/sshd.c	Tue Jul 20 00:53:16 1999
@@ -2420,7 +2420,12 @@
               log_msg("RhostsRsa authentication not available for session encrypted with arcfour.");
               break;
             }
-
+	  if (cipher_type == SSH_CIPHER_ROT13)
+	    {
+	      packet_get_all();
+	      log_msg("RhostsRsa authentication not available for session encrypted with ROT13.");
+	      break;
+	    }
           /* Get client user name.  Note that we just have to trust the client;
              root on the client machine can claim to be any user. */
           client_user = packet_get_string(NULL);