From: Phil Thompson <phil@river-bank.demon.co.uk>

I've completed the patch to fix the protocol and authentication issues I
was discussing a couple of weeks ago.  The particular changes are:

- the protocol has a version number
- network byte order is used throughout
- the pg_hba.conf file is used to specify what method is used to
  authenticate a frontend (either password, ident, trust, reject, krb4
  or krb5)
- support for multiplexed backends is removed
- appropriate changes to man pages
- the -a switch to many programs to specify an authentication service
  no longer has any effect
- the libpq.so version number has changed to 1.1

The new backend still supports the old protocol so old interfaces won't
break.

src/backend/libpq/crypt.c

@@ -17,9 +17,6 @@
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
-#ifdef HAVE_CRYPT_H
-#include <crypt.h>
-#endif
 
 #include "postgres.h"
 #include "miscadmin.h"
@@ -27,6 +24,10 @@
 #include "storage/fd.h"
 #include "libpq/crypt.h"
 
+#ifdef HAVE_CRYPT_H
+#include <crypt.h>
+#endif
+
 char**     pwd_cache = NULL;
 int        pwd_cache_count = 0;
 
@@ -219,6 +220,7 @@ int crypt_getloginfo(const char* user, char** passwd, char** valuntil) {
 
 /*-------------------------------------------------------------------------*/
 
+#ifdef 0
 MsgType crypt_salt(const char* user) {
 
   char*     passwd;
@@ -237,6 +239,7 @@ MsgType crypt_salt(const char* user) {
   if (valuntil) free((void*)valuntil);
   return STARTUP_SALT_MSG;
 }
+#endif
 
 /*-------------------------------------------------------------------------*/
 
@@ -258,7 +261,13 @@ int crypt_verify(Port* port, const char* user, const char* pgpass) {
     return STATUS_ERROR;
   }
 
-  crypt_pwd = crypt(passwd, port->salt);
+  /*
+   * Compare with the encrypted or plain password depending on the
+   * authentication method being used for this connection.
+   */
+
+  crypt_pwd = (port->auth_method == uaCrypt ? crypt(passwd, port->salt) : passwd);
+
   if (!strcmp(pgpass, crypt_pwd)) {
     /* check here to be sure we are not past valuntil
      */