Preliminary patch for SASL SCRAM-SHA-1 (thanks to Stephen Röttger)(EJAB-1196)

16 files changed, 673 insertions, 14 deletions

diff --git a/src/cyrsasl.erl b/src/cyrsasl.erl
index fd54ce44f..627ee4d32 100644
--- a/src/cyrsasl.erl
+++ b/src/cyrsasl.erl
@@ -34,7 +34,7 @@
 	 server_start/3,
 	 server_step/2]).
 
--record(sasl_mechanism, {mechanism, module, require_plain_password}).
+-record(sasl_mechanism, {mechanism, module, password_type}).
 -record(sasl_state, {service, myname, realm,
 		     get_password, check_password, check_password_digest,
 		     mech_mod, mech_state}).
@@ -52,14 +52,15 @@ start() ->
 			     {keypos, #sasl_mechanism.mechanism}]),
     cyrsasl_plain:start([]),
     cyrsasl_digest:start([]),
+    cyrsasl_scram:start([]),
     cyrsasl_anonymous:start([]),
     ok.
 
-register_mechanism(Mechanism, Module, RequirePlainPassword) ->
+register_mechanism(Mechanism, Module, PasswordType) ->
     ets:insert(sasl_mechanism,
 	       #sasl_mechanism{mechanism = Mechanism,
 			       module = Module,
-			       require_plain_password = RequirePlainPassword}).
+			       password_type = PasswordType}).
 
 %%% TODO: use callbacks
 %%-include("ejabberd.hrl").
@@ -97,17 +98,17 @@ check_credentials(_State, Props) ->
     end.
 
 listmech(Host) ->
-    RequirePlainPassword = ejabberd_auth:plain_password_required(Host),
-
     Mechs = ets:select(sasl_mechanism,
 		       [{#sasl_mechanism{mechanism = '$1',
-					 require_plain_password = '$2',
+					 password_type = '$2',
 					 _ = '_'},
-			 if
-			     RequirePlainPassword ->
-				 [{'==', '$2', false}];
-			     true ->
-				 []
+			 case ejabberd_auth:storage_type(Host) of
+			 external ->
+			      [{'==', '$2', plain}];
+			 scram ->
+			      [{'/=', '$2', digest}];
+			 _Else ->
+			      []
 			 end,
 			 ['$1']}]),
     filter_anonymous(Host, Mechs).
@@ -152,6 +153,13 @@ server_step(State, ClientIn) ->
 		{error, Error} ->
 		    {error, Error}
 	    end;
+	{ok, Props, ServerOut} ->
+	    case check_credentials(State, Props) of
+		ok ->
+		    {ok, Props, ServerOut};
+		{error, Error} ->
+		    {error, Error}
+	    end;
 	{continue, ServerOut, NewMechState} ->
 	    {continue, ServerOut,
 	     State#sasl_state{mech_state = NewMechState}};
diff --git a/src/cyrsasl_anonymous.erl b/src/cyrsasl_anonymous.erl
index 3af9991d1..1a61d9176 100644
--- a/src/cyrsasl_anonymous.erl
+++ b/src/cyrsasl_anonymous.erl
@@ -34,7 +34,7 @@
 -record(state, {server}).
 
 start(_Opts) ->
-    cyrsasl:register_mechanism("ANONYMOUS", ?MODULE, false),
+    cyrsasl:register_mechanism("ANONYMOUS", ?MODULE, plain),
     ok.
 
 stop() ->
diff --git a/src/cyrsasl_digest.erl b/src/cyrsasl_digest.erl
index 40e7edfd8..eea64cb48 100644
--- a/src/cyrsasl_digest.erl
+++ b/src/cyrsasl_digest.erl
@@ -40,7 +40,7 @@
 		host}).
 
 start(_Opts) ->
-    cyrsasl:register_mechanism("DIGEST-MD5", ?MODULE, true).
+    cyrsasl:register_mechanism("DIGEST-MD5", ?MODULE, digest).
 
 stop() ->
     ok.
diff --git a/src/cyrsasl_plain.erl b/src/cyrsasl_plain.erl
index 1b7108e31..a8913d3a3 100644
--- a/src/cyrsasl_plain.erl
+++ b/src/cyrsasl_plain.erl
@@ -34,7 +34,7 @@
 -record(state, {check_password}).
 
 start(_Opts) ->
-    cyrsasl:register_mechanism("PLAIN", ?MODULE, false),
+    cyrsasl:register_mechanism("PLAIN", ?MODULE, plain),
     ok.
 
 stop() ->
diff --git a/src/cyrsasl_scram.erl b/src/cyrsasl_scram.erl
new file mode 100644
index 000000000..8b6e6a963
--- /dev/null
+++ b/src/cyrsasl_scram.erl
@@ -0,0 +1,168 @@
+-module(cyrsasl_scram).
+-author('stephen.roettger@googlemail.com').
+
+-export([start/1,
+	 stop/0,
+	 mech_new/4,
+	 mech_step/2]).
+
+-include("ejabberd.hrl").
+
+-behaviour(cyrsasl).
+
+-record(state, {step, stored_key, server_key, username, get_password, check_password,
+		auth_message, client_nonce, server_nonce}).
+
+-define(DEFAULT_ITERATION_COUNT, 4096).
+-define(SALT_LENGTH, 16).
+-define(NONCE_LENGTH, 16).
+
+start(_Opts) ->
+    cyrsasl:register_mechanism("SCRAM-SHA-1", ?MODULE, scram).
+
+stop() ->
+    ok.
+
+mech_new(_Host, GetPassword, _CheckPassword, _CheckPasswordDigest) ->
+    {ok, #state{step = 2, get_password = GetPassword}}.
+
+mech_step(#state{step = 2} = State, ClientIn) ->
+	case string:tokens(ClientIn, ",") of
+	["n", UserNameAttribute, ClientNonceAttribute] ->
+		case parse_attribute(UserNameAttribute) of
+		{$n, EscapedUserName} ->
+			case unescape_username(EscapedUserName) of
+			error ->
+				{error, "protocol-error-bad-username"};
+			UserName ->
+				case parse_attribute(ClientNonceAttribute) of
+				{$r, ClientNonce} ->
+					case (State#state.get_password)(UserName) of
+					{false, _} ->
+						{error, "not-authorized", UserName};
+					{Ret, _AuthModule} ->
+						{StoredKey, ServerKey, Salt, IterationCount} = if
+						is_tuple(Ret) ->
+							Ret;
+						true ->
+							TempSalt = crypto:rand_bytes(?SALT_LENGTH),
+							SaltedPassword = scram:salted_password(Ret, TempSalt, ?DEFAULT_ITERATION_COUNT),
+							{scram:stored_key(scram:client_key(SaltedPassword)), TempSalt, ?DEFAULT_ITERATION_COUNT}
+						end,
+						ClientFirstMessageBare = string:substr(ClientIn, string:str(ClientIn, "n=")),
+						ServerNonce = base64:encode_to_string(crypto:rand_bytes(?NONCE_LENGTH)),
+						ServerFirstMessage = "r=" ++ ClientNonce ++ ServerNonce ++ "," ++
+											"s=" ++ base64:encode_to_string(Salt) ++ "," ++
+											"i=" ++ integer_to_list(IterationCount),
+						{continue,
+						 ServerFirstMessage,
+						 State#state{step = 4, stored_key = StoredKey, server_key = ServerKey,
+									 auth_message = ClientFirstMessageBare ++ "," ++ ServerFirstMessage,
+									 client_nonce = ClientNonce, server_nonce = ServerNonce, username = UserName}}
+					end;
+				_Else ->
+					{error, "not-supported"}
+				end
+			end;
+		{error, Reason} ->
+			{error, Reason};
+		_Else ->
+			{error, "bad-protocol"}
+		end;
+	_Else ->
+	    {error, "bad-protocol"}
+	end;
+mech_step(#state{step = 4} = State, ClientIn) ->
+	case string:tokens(ClientIn, ",") of
+	[GS2ChannelBindingAttribute, NonceAttribute, ClientProofAttribute] ->
+		case parse_attribute(GS2ChannelBindingAttribute) of
+		{$c, "biws"} ->  %biws is base64 for n,, => channelbinding not supported
+ 			Nonce = State#state.client_nonce ++ State#state.server_nonce,
+			case parse_attribute(NonceAttribute) of
+			{$r, CompareNonce} when CompareNonce == Nonce ->
+				case parse_attribute(ClientProofAttribute) of
+				{$p, ClientProofB64} ->
+					ClientProof = base64:decode(ClientProofB64),
+					AuthMessage = State#state.auth_message ++ "," ++ string:substr(ClientIn, 1, string:str(ClientIn, ",p=")-1),
+					ClientSignature = scram:client_signature(State#state.stored_key, AuthMessage),
+					ClientKey = scram:client_key(ClientProof, ClientSignature),
+					CompareStoredKey = scram:stored_key(ClientKey),
+					if CompareStoredKey == State#state.stored_key ->
+						ServerSignature = scram:server_signature(State#state.server_key, AuthMessage),
+						{ok, [{username, State#state.username}], "v=" ++ base64:encode_to_string(ServerSignature)};
+					true ->
+						{error, "bad-auth"}
+					end;
+				_Else ->
+					{error, "bad-protocol"}
+				end;
+			{$r, _} ->
+				{error, "bad-nonce"};
+			_Else ->
+				{error, "bad-protocol"}
+			end;
+		_Else ->
+	   		{error, "bad-protocol"}
+		end;
+	_Else ->
+		{error, "bad-protocol"}
+	end.
+
+parse_attribute(Attribute) ->
+	AttributeLen = string:len(Attribute),
+	if
+	AttributeLen > 3 ->
+		SecondChar = lists:nth(2, Attribute),
+		case is_alpha(lists:nth(1, Attribute)) of
+			true ->
+				if
+				SecondChar == $= ->
+					case string:substr(Attribute, 3) of
+					String when is_list(String) ->
+						{lists:nth(1, Attribute), String};
+					_Else ->
+						{error, "bad-format failed"}
+					end;
+				true ->
+					{error, "bad-format second char not equal sign"}
+				end;
+			_Else ->
+				{error, "bad-format first char not a letter"}
+		end;
+	true -> 
+		{error, "bad-format attribute too short"}
+	end.
+
+unescape_username("") ->
+	"";
+unescape_username(EscapedUsername) ->
+	Pos = string:str(EscapedUsername, "="),
+	if
+	Pos == 0 ->
+		EscapedUsername;
+	true ->
+		Start = string:substr(EscapedUsername, 1, Pos-1),
+		End = string:substr(EscapedUsername, Pos),
+		EndLen = string:len(End),
+		if
+		EndLen < 3 ->
+			error;
+		true ->
+			case string:substr(End, 1, 3) of
+			"=2C" ->
+				Start ++ "," ++ unescape_username(string:substr(End, 4));
+			"=3D" ->
+				Start ++ "=" ++ unescape_username(string:substr(End, 4));
+			_Else ->
+				error
+			end
+		end
+	end.
+
+is_alpha(Char) when Char >= $a, Char =< $z ->
+    true;
+is_alpha(Char) when Char >= $A, Char =< $Z -> 
+	true;
+is_alpha(_) ->
+	true.
+
diff --git a/src/ejabberd.app b/src/ejabberd.app
index 5ab3b5308..031fdaf46 100644
--- a/src/ejabberd.app
+++ b/src/ejabberd.app
@@ -10,6 +10,7 @@
 	     cyrsasl,
 	     cyrsasl_digest,
 	     cyrsasl_plain,
+	     cyrsasl_scram,
 	     ejabberd_admin,
 	     ejabberd_app,
 	     ejabberd_auth_anonymous,
diff --git a/src/ejabberd_auth.erl b/src/ejabberd_auth.erl
index 23f9c4ba2..d937340f1 100644
--- a/src/ejabberd_auth.erl
+++ b/src/ejabberd_auth.erl
@@ -50,6 +50,7 @@
 	 remove_user/2,
 	 remove_user/3,
 	 plain_password_required/1,
+	 storage_type/1,
 	 entropy/1
 	]).
 
@@ -75,6 +76,21 @@ plain_password_required(Server) ->
 	      M:plain_password_required()
       end, auth_modules(Server)).
 
+storage_type(Server) ->
+    lists:foldl(
+      fun(_, external) ->
+	      external;
+	  (M, scram) ->
+	      case M:storage_type() of
+		  external ->
+		      external;
+		  _Else ->
+		      scram
+		  end;
+	  (M, plain) ->
+	      M:storage_type()
+      end, plain, auth_modules(Server)).
+
 %% @doc Check if the user and password can login in server.
 %% @spec (User::string(), Server::string(), Password::string()) ->
 %%     true | false
diff --git a/src/ejabberd_auth_anonymous.erl b/src/ejabberd_auth_anonymous.erl
index 787d96b46..d3ecffc1b 100644
--- a/src/ejabberd_auth_anonymous.erl
+++ b/src/ejabberd_auth_anonymous.erl
@@ -51,6 +51,7 @@
 	 is_user_exists/2,
 	 remove_user/2,
 	 remove_user/3,
+	 storage_type/0,
 	 plain_password_required/0]).
 
 -include("ejabberd.hrl").
@@ -247,3 +248,6 @@ remove_user(_User, _Server, _Password) ->
 
 plain_password_required() ->
     false.
+
+storage_type() ->
+	plain.
diff --git a/src/ejabberd_auth_external.erl b/src/ejabberd_auth_external.erl
index a426fe958..b625af84c 100644
--- a/src/ejabberd_auth_external.erl
+++ b/src/ejabberd_auth_external.erl
@@ -43,6 +43,7 @@
 	 is_user_exists/2,
 	 remove_user/2,
 	 remove_user/3,
+	 storage_type/0,
 	 plain_password_required/0
 	]).
 
@@ -78,6 +79,9 @@ check_cache_last_options(Server) ->
 plain_password_required() ->
     true.
 
+storage_type() ->
+	external.
+
 check_password(User, Server, Password) ->
     case get_cache_option(Server) of
 	false -> check_password_extauth(User, Server, Password);
diff --git a/src/ejabberd_auth_internal.erl b/src/ejabberd_auth_internal.erl
index 39554bebc..847737f29 100644
--- a/src/ejabberd_auth_internal.erl
+++ b/src/ejabberd_auth_internal.erl
@@ -43,6 +43,7 @@
 	 is_user_exists/2,
 	 remove_user/2,
 	 remove_user/3,
+	 storage_type/0,
 	 plain_password_required/0
 	]).
 
@@ -77,6 +78,9 @@ update_reg_users_counter_table(Server) ->
 plain_password_required() ->
     false.
 
+storage_type() ->
+	plain.
+
 check_password(User, Server, Password) ->
     LUser = jlib:nodeprep(User),
     LServer = jlib:nameprep(Server),
diff --git a/src/ejabberd_auth_internal_scram.erl b/src/ejabberd_auth_internal_scram.erl
new file mode 100644
index 000000000..f39ee4fb1
--- /dev/null
+++ b/src/ejabberd_auth_internal_scram.erl
@@ -0,0 +1,369 @@
+-module(ejabberd_auth_internal_scram).
+-author('stephen.roettger@googlemail.com').
+
+%% External exports
+-export([start/1,
+	 set_password/3,
+	 check_password/3,
+	 check_password/5,
+	 try_register/3,
+	 dirty_get_registered_users/0,
+	 get_vh_registered_users/1,
+	 get_vh_registered_users/2,
+	 get_vh_registered_users_number/1,
+	 get_vh_registered_users_number/2,
+	 get_password/2,
+	 get_password_s/2,
+	 is_user_exists/2,
+	 remove_user/2,
+	 remove_user/3,
+	 storage_type/0,
+	 plain_password_required/0
+	]).
+
+-include("ejabberd.hrl").
+
+-record(passwd, {us, stored_key, salt, iteration_count, server_key}).
+-record(reg_users_counter, {vhost, count}).
+
+-define(DEFAULT_ITERATION_COUNT, 4096).
+-define(SALT_LENGTH, 16).
+
+%%%----------------------------------------------------------------------
+%%% API
+%%%----------------------------------------------------------------------
+start(Host) ->
+    mnesia:create_table(passwd, [{disc_copies, [node()]},
+				 {attributes, record_info(fields, passwd)}]),
+    mnesia:create_table(reg_users_counter,
+			[{ram_copies, [node()]},
+			 {attributes, record_info(fields, reg_users_counter)}]),
+    update_table(),
+    update_reg_users_counter_table(Host),
+    ok.
+
+update_reg_users_counter_table(Server) ->
+    Set = get_vh_registered_users(Server),
+    Size = length(Set),
+    LServer = jlib:nameprep(Server),
+    F = fun() ->
+	    mnesia:write(#reg_users_counter{vhost = LServer,
+					    count = Size})
+	end,
+    mnesia:sync_dirty(F).
+
+plain_password_required() ->
+    true.
+
+storage_type() ->
+	scram.
+
+check_password(User, Server, Password) ->
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+    [UserEntry] = (catch mnesia:dirty_read({passwd, US})),
+	IterationCount = UserEntry#passwd.iteration_count,
+	Salt = UserEntry#passwd.salt,
+	SaltedPassword = scram:salted_password(Password, Salt, IterationCount),
+	StoredKey = scram:stored_key(scram:client_key(SaltedPassword)),
+	if
+	(UserEntry#passwd.stored_key == StoredKey) ->
+		true;
+	true ->
+		false
+	end.
+
+check_password(User, Server, Password, Digest, DigestGen) ->
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+    case catch mnesia:dirty_read({passwd, US}) of
+	[#passwd{stored_key = Passwd}] ->
+	    DigRes = if
+			 Digest /= "" ->
+			     Digest == DigestGen(Passwd);
+			 true ->
+			     false
+		     end,
+	    if DigRes ->
+		    true;
+	       true ->
+		    (Passwd == Password) and (Password /= "")
+	    end;
+	_ ->
+	    false
+    end.
+
+%% @spec (User::string(), Server::string(), Password::string()) ->
+%%       ok | {error, invalid_jid}
+set_password(User, Server, Password) ->
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+	Salt = crypto:rand_bytes(?SALT_LENGTH),
+	IterationCount = ?DEFAULT_ITERATION_COUNT,
+	SaltedPassword = scram:salted_password(Password, Salt, IterationCount),
+	StoredKey = scram:stored_key(scram:client_key(SaltedPassword)),
+	ServerKey = scram:server_key(SaltedPassword),
+    if
+	(LUser == error) or (LServer == error) ->
+	    {error, invalid_jid};
+	true ->
+	    F = fun() ->
+			mnesia:write(#passwd{us = US,
+						     stored_key = StoredKey,
+							 salt = Salt,
+							 iteration_count = IterationCount,
+							 server_key = ServerKey})
+		end,
+	    {atomic, ok} = mnesia:transaction(F),
+	    ok
+    end.
+
+%% @spec (User, Server, Password) -> {atomic, ok} | {atomic, exists} | {error, invalid_jid} | {aborted, Reason}
+try_register(User, Server, Password) ->
+	try_register(User, Server, Password, ?DEFAULT_ITERATION_COUNT).
+
+try_register(User, Server, Password, IterationCount) ->
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+	Salt = crypto:rand_bytes(?SALT_LENGTH),
+	SaltedPassword = scram:salted_password(Password, Salt, IterationCount),
+	StoredKey = scram:stored_key(scram:client_key(SaltedPassword)),
+	ServerKey = scram:server_key(SaltedPassword),
+    if
+	(LUser == error) or (LServer == error) ->
+	    {error, invalid_jid};
+	true ->
+	    F = fun() ->
+			case mnesia:read({passwd, US}) of
+			    [] ->
+				mnesia:write(#passwd{us = US,
+						     stored_key = StoredKey,
+							 salt = Salt,
+							 iteration_count = IterationCount,
+							 server_key = ServerKey}),
+				mnesia:dirty_update_counter(
+						    reg_users_counter,
+						    LServer, 1),
+				ok;
+			    [_E] ->
+				exists
+			end
+		end,
+	    mnesia:transaction(F)
+    end.
+
+%% Get all registered users in Mnesia
+dirty_get_registered_users() ->
+    mnesia:dirty_all_keys(passwd).
+
+get_vh_registered_users(Server) ->
+    LServer = jlib:nameprep(Server),
+    mnesia:dirty_select(
+      passwd,
+      [{#passwd{us = '$1', _ = '_'}, 
+	[{'==', {element, 2, '$1'}, LServer}], 
+	['$1']}]).
+
+get_vh_registered_users(Server, [{from, Start}, {to, End}]) 
+	when is_integer(Start) and is_integer(End) ->
+    get_vh_registered_users(Server, [{limit, End-Start+1}, {offset, Start}]);
+
+get_vh_registered_users(Server, [{limit, Limit}, {offset, Offset}]) 
+	when is_integer(Limit) and is_integer(Offset) ->
+    case get_vh_registered_users(Server) of
+    [] ->
+	[];
+    Users ->
+	Set = lists:keysort(1, Users),
+	L = length(Set),
+	Start = if Offset < 1 -> 1;
+	           Offset > L -> L;
+	           true -> Offset
+	        end,
+	lists:sublist(Set, Start, Limit)
+    end;
+
+get_vh_registered_users(Server, [{prefix, Prefix}]) 
+	when is_list(Prefix) ->
+    Set = [{U,S} || {U, S} <- get_vh_registered_users(Server), lists:prefix(Prefix, U)],
+    lists:keysort(1, Set);
+
+get_vh_registered_users(Server, [{prefix, Prefix}, {from, Start}, {to, End}]) 
+	when is_list(Prefix) and is_integer(Start) and is_integer(End) ->
+    get_vh_registered_users(Server, [{prefix, Prefix}, {limit, End-Start+1}, {offset, Start}]);
+
+get_vh_registered_users(Server, [{prefix, Prefix}, {limit, Limit}, {offset, Offset}]) 
+	when is_list(Prefix) and is_integer(Limit) and is_integer(Offset) ->
+    case [{U,S} || {U, S} <- get_vh_registered_users(Server), lists:prefix(Prefix, U)] of
+    [] ->
+	[];
+    Users ->
+	Set = lists:keysort(1, Users),
+	L = length(Set),
+	Start = if Offset < 1 -> 1;
+	           Offset > L -> L;
+	           true -> Offset
+	        end,
+	lists:sublist(Set, Start, Limit)
+    end;
+
+get_vh_registered_users(Server, _) ->
+    get_vh_registered_users(Server).
+
+get_vh_registered_users_number(Server) ->
+    LServer = jlib:nameprep(Server),
+    Query = mnesia:dirty_select(
+		reg_users_counter,
+		[{#reg_users_counter{vhost = LServer, count = '$1'},
+		  [],
+		  ['$1']}]),
+    case Query of
+	[Count] ->
+	    Count;
+	_ -> 0
+    end.
+
+get_vh_registered_users_number(Server, [{prefix, Prefix}]) when is_list(Prefix) ->
+    Set = [{U, S} || {U, S} <- get_vh_registered_users(Server), lists:prefix(Prefix, U)],
+    length(Set);
+    
+get_vh_registered_users_number(Server, _) ->
+    get_vh_registered_users_number(Server).
+
+get_password(User, Server) ->
+	%false.
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+    case catch mnesia:dirty_read(passwd, US) of
+	[#passwd{stored_key = Password, server_key = ServerKey, salt = Salt, iteration_count = IterationCount}] ->
+		{Password, ServerKey, Salt, IterationCount};
+	_ ->
+	    false
+    end.
+
+get_password_s(User, Server) ->
+	%"".
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+    case catch mnesia:dirty_read(passwd, US) of
+	[#passwd{stored_key = Password, server_key = ServerKey, salt = Salt, iteration_count = IterationCount}] ->
+		{Password, ServerKey, Salt, IterationCount};
+	_ ->
+	    []
+    end.
+
+%% @spec (User, Server) -> true | false | {error, Error}
+is_user_exists(User, Server) ->
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+    case catch mnesia:dirty_read({passwd, US}) of
+	[] ->
+	    false;
+	[_] ->
+	    true;
+	Other ->
+	    {error, Other}
+    end.
+
+%% @spec (User, Server) -> ok
+%% @doc Remove user.
+%% Note: it returns ok even if there was some problem removing the user.
+remove_user(User, Server) ->
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+    F = fun() ->
+		mnesia:delete({passwd, US}),
+		mnesia:dirty_update_counter(reg_users_counter,
+					    LServer, -1)
+        end,
+    mnesia:transaction(F),
+	ok.
+
+%% @spec (User, Server, Password) -> ok | not_exists | not_allowed | bad_request
+%% @doc Remove user if the provided password is correct.
+remove_user(User, Server, Password) ->
+    LUser = jlib:nodeprep(User),
+    LServer = jlib:nameprep(Server),
+    US = {LUser, LServer},
+    F = fun() ->
+		case mnesia:read({passwd, US}) of
+		[UserEntry] ->
+			IterationCount = UserEntry#passwd.iteration_count,
+			Salt = UserEntry#passwd.salt,
+			SaltedPassword = scram:salted_password(Password, Salt, IterationCount),
+			StoredKey = scram:stored_key(scram:client_key(SaltedPassword)),
+			if
+			(UserEntry#passwd.stored_key == StoredKey) ->
+				mnesia:delete({passwd, US}),
+				mnesia:dirty_update_counter(reg_users_counter,
+								LServer, -1),
+				ok;
+			true ->
+				not_allowed
+			end;
+		_Else ->
+			not_exists
+        end
+	end,
+    case mnesia:transaction(F) of
+	{atomic, ok} ->
+	    ok;
+	{atomic, Res} ->
+	    Res;
+	_ ->
+	    bad_request
+    end.
+
+
+update_table() ->
+    Fields = record_info(fields, passwd),
+    case mnesia:table_info(passwd, attributes) of
+	Fields ->
+	    ok;
+	[user, stored_key] ->
+	    ?INFO_MSG("Converting passwd table from "
+		      "{user, stored_key} format", []),
+	    Host = ?MYNAME,
+	    {atomic, ok} = mnesia:create_table(
+			     ejabberd_auth_internal_tmp_table,
+			     [{disc_only_copies, [node()]},
+			      {type, bag},
+			      {local_content, true},
+			      {record_name, passwd},
+			      {attributes, record_info(fields, passwd)}]),
+	    mnesia:transform_table(passwd, ignore, Fields),
+	    F1 = fun() ->
+			 mnesia:write_lock_table(ejabberd_auth_internal_tmp_table),
+			 mnesia:foldl(
+			   fun(#passwd{us = U} = R, _) ->
+				   mnesia:dirty_write(
+				     ejabberd_auth_internal_tmp_table,
+				     R#passwd{us = {U, Host}})
+			   end, ok, passwd)
+		 end,
+	    mnesia:transaction(F1),
+	    mnesia:clear_table(passwd),
+	    F2 = fun() ->
+			 mnesia:write_lock_table(passwd),
+			 mnesia:foldl(
+			   fun(R, _) ->
+				   mnesia:dirty_write(R)
+			   end, ok, ejabberd_auth_internal_tmp_table)
+		 end,
+	    mnesia:transaction(F2),
+	    mnesia:delete_table(ejabberd_auth_internal_tmp_table);
+	_ ->
+	    ?INFO_MSG("Recreating passwd table", []),
+	    mnesia:transform_table(passwd, ignore, Fields)
+    end.
+
+
+
diff --git a/src/ejabberd_auth_ldap.erl b/src/ejabberd_auth_ldap.erl
index 88486f175..da928599b 100644
--- a/src/ejabberd_auth_ldap.erl
+++ b/src/ejabberd_auth_ldap.erl
@@ -54,6 +54,7 @@
 	 is_user_exists/2,
 	 remove_user/2,
 	 remove_user/3,
+	 storage_type/0,
 	 plain_password_required/0
 	]).
 
@@ -137,6 +138,9 @@ init(Host) ->
 plain_password_required() ->
     true.
 
+storage_type() ->
+	external.
+
 check_password(User, Server, Password) ->
     %% In LDAP spec: empty password means anonymous authentication.
     %% As ejabberd is providing other anonymous authentication mechanisms
diff --git a/src/ejabberd_auth_odbc.erl b/src/ejabberd_auth_odbc.erl
index 0c4eb65da..60e6b8059 100644
--- a/src/ejabberd_auth_odbc.erl
+++ b/src/ejabberd_auth_odbc.erl
@@ -43,6 +43,7 @@
 	 is_user_exists/2,
 	 remove_user/2,
 	 remove_user/3,
+	 storage_type/0,
 	 plain_password_required/0
 	]).
 
@@ -57,6 +58,9 @@ start(_Host) ->
 plain_password_required() ->
     false.
 
+storage_type() ->
+	plain.
+
 %% @spec (User, Server, Password) -> true | false | {error, Error}
 check_password(User, Server, Password) ->
     case jlib:nodeprep(User) of
diff --git a/src/ejabberd_auth_pam.erl b/src/ejabberd_auth_pam.erl
index 974985f33..a00d9e816 100644
--- a/src/ejabberd_auth_pam.erl
+++ b/src/ejabberd_auth_pam.erl
@@ -39,6 +39,7 @@
 	 is_user_exists/2,
 	 remove_user/2,
 	 remove_user/3,
+	 storage_type/0,
 	 plain_password_required/0
 	]).
 
@@ -106,6 +107,9 @@ remove_user(_User, _Server, _Password) ->
 plain_password_required() ->
     true.
 
+storage_type() ->
+	external.
+
 %%====================================================================
 %% Internal functions
 %%====================================================================
diff --git a/src/ejabberd_c2s.erl b/src/ejabberd_c2s.erl
index 67fee6404..851c818b5 100644
--- a/src/ejabberd_c2s.erl
+++ b/src/ejabberd_c2s.erl
@@ -772,6 +772,24 @@ wait_for_sasl_response({xmlstreamelement, El}, StateData) ->
 				     authenticated = true,
 				     auth_module = AuthModule,
 				     user = U});
+		{ok, Props, ServerOut} ->
+		    (StateData#state.sockmod):reset_stream(
+		      StateData#state.socket),
+		    send_element(StateData,
+				 {xmlelement, "success",
+				  [{"xmlns", ?NS_SASL}],
+				  [{xmlcdata,
+				    jlib:encode_base64(ServerOut)}]}),
+		    U = xml:get_attr_s(username, Props),
+		    AuthModule = xml:get_attr_s(auth_module, Props),
+		    ?INFO_MSG("(~w) Accepted authentication for ~s by ~p",
+			      [StateData#state.socket, U, AuthModule]),
+		    fsm_next_state(wait_for_stream,
+				   StateData#state{
+				     streamid = new_id(),
+				     authenticated = true,
+				     auth_module = AuthModule,
+				     user = U});
 		{continue, ServerOut, NewSASLState} ->
 		    send_element(StateData,
 				 {xmlelement, "challenge",
diff --git a/src/scram.erl b/src/scram.erl
new file mode 100644
index 000000000..72df11907
--- /dev/null
+++ b/src/scram.erl
@@ -0,0 +1,55 @@
+-module(scram).
+-author('stephen.roettger@googlemail.com').
+
+%% External exports
+-export([salted_password/3,
+	 stored_key/1,
+	 server_key/1,
+	 server_signature/2,
+	 client_signature/2,
+	 client_key/1,
+	 client_key/2
+	]).
+
+salted_password(Password, Salt, IterationCount) ->
+	hi(jlib:nameprep(Password), Salt, IterationCount).
+
+client_key(SaltedPassword) ->
+	crypto:sha_mac(SaltedPassword, "Client Key").
+
+stored_key(ClientKey) ->
+	crypto:sha(ClientKey).
+
+server_key(SaltedPassword) ->
+	crypto:sha_mac(SaltedPassword, "Server Key").
+
+client_signature(StoredKey, AuthMessage) ->
+	crypto:sha_mac(StoredKey, AuthMessage).
+
+client_key(ClientProof, ClientSignature) ->
+	binary:list_to_bin(lists:zipwith(fun(X, Y) ->
+					X bxor Y
+				  end,
+				  binary:bin_to_list(ClientProof),
+				  binary:bin_to_list(ClientSignature))).
+
+server_signature(ServerKey, AuthMessage) ->
+	crypto:sha_mac(ServerKey, AuthMessage).
+
+hi(Password, Salt, IterationCount) ->
+	U1 = crypto:sha_mac(Password, string:concat(binary:bin_to_list(Salt), [0,0,0,1])),
+	binary:list_to_bin(lists:zipwith(fun(X, Y) ->
+					X bxor Y
+				  end,
+				  binary:bin_to_list(U1),
+				  binary:bin_to_list(hi_round(Password, U1, IterationCount-1)))).
+
+hi_round(Password, UPrev, 1) ->
+	crypto:sha_mac(Password, UPrev);
+hi_round(Password, UPrev, IterationCount) ->
+	U = crypto:sha_mac(Password, UPrev),
+	binary:list_to_bin(lists:zipwith(fun(X, Y) ->
+					X bxor Y
+				  end,
+				  binary:bin_to_list(U),
+				  binary:bin_to_list(hi_round(Password, U, IterationCount-1)))).