218 lines
6.3 KiB
Erlang
218 lines
6.3 KiB
Erlang
%%%----------------------------------------------------------------------
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%%% File : cyrsasl_digest.erl
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%%% Author : Alexey Shchepin <alexey@sevcom.net>
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%%% Purpose : DIGEST-MD5 SASL mechanism
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%%% Created : 11 Mar 2003 by Alexey Shchepin <alexey@sevcom.net>
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%%%
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%%%
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%%% ejabberd, Copyright (C) 2002-2010 ProcessOne
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%%%
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%%% This program is free software; you can redistribute it and/or
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%%% modify it under the terms of the GNU General Public License as
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%%% published by the Free Software Foundation; either version 2 of the
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%%% License, or (at your option) any later version.
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%%%
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%%% This program is distributed in the hope that it will be useful,
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%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
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%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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%%% General Public License for more details.
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%%%
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%%% You should have received a copy of the GNU General Public License
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%%% along with this program; if not, write to the Free Software
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%%% Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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%%% 02111-1307 USA
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%%%
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%%%----------------------------------------------------------------------
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-module(cyrsasl_digest).
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-author('alexey@sevcom.net').
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-export([start/1,
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stop/0,
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mech_new/4,
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mech_step/2]).
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-include("ejabberd.hrl").
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-behaviour(cyrsasl).
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-record(state, {step, nonce, username, authzid, get_password, check_password, auth_module,
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host}).
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start(_Opts) ->
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cyrsasl:register_mechanism("DIGEST-MD5", ?MODULE, true).
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stop() ->
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ok.
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mech_new(Host, GetPassword, _CheckPassword, CheckPasswordDigest) ->
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{ok, #state{step = 1,
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nonce = randoms:get_string(),
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host = Host,
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get_password = GetPassword,
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check_password = CheckPasswordDigest}}.
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mech_step(#state{step = 1, nonce = Nonce} = State, _) ->
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{continue,
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"nonce=\"" ++ Nonce ++
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"\",qop=\"auth\",charset=utf-8,algorithm=md5-sess",
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State#state{step = 3}};
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mech_step(#state{step = 3, nonce = Nonce} = State, ClientIn) ->
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case parse(ClientIn) of
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bad ->
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{error, "bad-protocol"};
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KeyVals ->
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DigestURI = xml:get_attr_s("digest-uri", KeyVals),
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UserName = xml:get_attr_s("username", KeyVals),
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case is_digesturi_valid(DigestURI, State#state.host) of
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false ->
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?DEBUG("User login not authorized because digest-uri "
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"seems invalid: ~p", [DigestURI]),
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{error, "not-authorized", UserName};
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true ->
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AuthzId = xml:get_attr_s("authzid", KeyVals),
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case (State#state.get_password)(UserName) of
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{false, _} ->
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{error, "not-authorized", UserName};
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{Passwd, AuthModule} ->
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case (State#state.check_password)(UserName, "",
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xml:get_attr_s("response", KeyVals),
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fun(PW) -> response(KeyVals, UserName, PW, Nonce, AuthzId,
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"AUTHENTICATE") end) of
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{true, _} ->
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RspAuth = response(KeyVals,
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UserName, Passwd,
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Nonce, AuthzId, ""),
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{continue,
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"rspauth=" ++ RspAuth,
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State#state{step = 5,
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auth_module = AuthModule,
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username = UserName,
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authzid = AuthzId}};
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false ->
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{error, "not-authorized", UserName};
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{false, _} ->
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{error, "not-authorized", UserName}
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end
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end
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end
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end;
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mech_step(#state{step = 5,
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auth_module = AuthModule,
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username = UserName,
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authzid = AuthzId}, "") ->
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{ok, [{username, UserName}, {authzid, AuthzId},
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{auth_module, AuthModule}]};
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mech_step(A, B) ->
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?DEBUG("SASL DIGEST: A ~p B ~p", [A,B]),
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{error, "bad-protocol"}.
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parse(S) ->
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parse1(S, "", []).
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parse1([$= | Cs], S, Ts) ->
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parse2(Cs, lists:reverse(S), "", Ts);
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parse1([$, | Cs], [], Ts) ->
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parse1(Cs, [], Ts);
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parse1([$\s | Cs], [], Ts) ->
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parse1(Cs, [], Ts);
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parse1([C | Cs], S, Ts) ->
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parse1(Cs, [C | S], Ts);
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parse1([], [], T) ->
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lists:reverse(T);
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parse1([], _S, _T) ->
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bad.
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parse2([$\" | Cs], Key, Val, Ts) ->
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parse3(Cs, Key, Val, Ts);
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parse2([C | Cs], Key, Val, Ts) ->
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parse4(Cs, Key, [C | Val], Ts);
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parse2([], _, _, _) ->
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bad.
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parse3([$\" | Cs], Key, Val, Ts) ->
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parse4(Cs, Key, Val, Ts);
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parse3([$\\, C | Cs], Key, Val, Ts) ->
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parse3(Cs, Key, [C | Val], Ts);
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parse3([C | Cs], Key, Val, Ts) ->
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parse3(Cs, Key, [C | Val], Ts);
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parse3([], _, _, _) ->
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bad.
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parse4([$, | Cs], Key, Val, Ts) ->
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parse1(Cs, "", [{Key, lists:reverse(Val)} | Ts]);
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parse4([$\s | Cs], Key, Val, Ts) ->
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parse4(Cs, Key, Val, Ts);
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parse4([C | Cs], Key, Val, Ts) ->
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parse4(Cs, Key, [C | Val], Ts);
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parse4([], Key, Val, Ts) ->
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parse1([], "", [{Key, lists:reverse(Val)} | Ts]).
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%% @doc Check if the digest-uri is valid.
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%% RFC-2831 allows to provide the IP address in Host,
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%% however ejabberd doesn't allow that.
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%% If the service (for example jabber.example.org)
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%% is provided by several hosts (being one of them server3.example.org),
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%% then digest-uri can be like xmpp/server3.example.org/jabber.example.org
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%% In that case, ejabberd only checks the service name, not the host.
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is_digesturi_valid(DigestURICase, JabberHost) ->
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DigestURI = stringprep:tolower(DigestURICase),
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case catch string:tokens(DigestURI, "/") of
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["xmpp", Host] when Host == JabberHost ->
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true;
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["xmpp", _Host, ServName] when ServName == JabberHost ->
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true;
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_ ->
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false
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end.
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digit_to_xchar(D) when (D >= 0) and (D < 10) ->
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D + 48;
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digit_to_xchar(D) ->
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D + 87.
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hex(S) ->
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hex(S, []).
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hex([], Res) ->
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lists:reverse(Res);
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hex([N | Ns], Res) ->
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hex(Ns, [digit_to_xchar(N rem 16),
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digit_to_xchar(N div 16) | Res]).
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response(KeyVals, User, Passwd, Nonce, AuthzId, A2Prefix) ->
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Realm = xml:get_attr_s("realm", KeyVals),
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CNonce = xml:get_attr_s("cnonce", KeyVals),
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DigestURI = xml:get_attr_s("digest-uri", KeyVals),
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NC = xml:get_attr_s("nc", KeyVals),
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QOP = xml:get_attr_s("qop", KeyVals),
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A1 = case AuthzId of
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"" ->
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binary_to_list(
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crypto:md5(User ++ ":" ++ Realm ++ ":" ++ Passwd)) ++
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":" ++ Nonce ++ ":" ++ CNonce;
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_ ->
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binary_to_list(
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crypto:md5(User ++ ":" ++ Realm ++ ":" ++ Passwd)) ++
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":" ++ Nonce ++ ":" ++ CNonce ++ ":" ++ AuthzId
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end,
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A2 = case QOP of
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"auth" ->
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A2Prefix ++ ":" ++ DigestURI;
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_ ->
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A2Prefix ++ ":" ++ DigestURI ++
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":00000000000000000000000000000000"
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end,
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T = hex(binary_to_list(crypto:md5(A1))) ++ ":" ++ Nonce ++ ":" ++
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NC ++ ":" ++ CNonce ++ ":" ++ QOP ++ ":" ++
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hex(binary_to_list(crypto:md5(A2))),
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hex(binary_to_list(crypto:md5(T))).
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