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+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2008-2009. All Rights Reserved.
+%%
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+%%
+
+%%% Description: Reading and writing of PEM type encoded files.
+%% PEM encoded files have the following structure:
+%%
+%% <text>
+%% -----BEGIN SOMETHING-----<CR><LF>
+%% <Base64 encoding line><CR><LF>
+%% <Base64 encoding line><CR><LF>
+%% ...
+%% -----END SOMETHING-----<CR><LF>
+%% <text>
+%%
+%% A file can contain several BEGIN/END blocks. Text lines between
+%% blocks are ignored.
+%%
+%% The encoding is divided into lines separated by <NL>, and each line
+%% is precisely 64 characters long (excluding the <NL> characters,
+%% except the last line which 64 characters long or shorter. <NL> may
+%% follow the last line.
+
+-module(pubkey_pem).
+
+-export([read_file/1, read_file/2, write_file/2, decode/2]).
+-export([decode_key/2]).
+
+-define(ENCODED_LINE_LENGTH, 64).
+
+%%====================================================================
+%% Internal application API
+%%====================================================================
+read_file(File) ->
+ read_file(File, no_passwd).
+
+read_file(File, Passwd) ->
+ {ok, Bin} = file:read_file(File),
+ decode(Bin, Passwd).
+
+write_file(File, Ds) ->
+ file:write_file(File, encode_file(Ds)).
+
+decode_key({_Type, Bin, not_encrypted}, _) ->
+ Bin;
+decode_key({_Type, Bin, {Chipher,Salt}}, Password) ->
+ decode_key(Bin, Password, Chipher, Salt).
+
+decode(Bin, Passwd) ->
+ decode_file(split_bin(Bin), Passwd).
+
+%%--------------------------------------------------------------------
+%%% Internal functions
+%%--------------------------------------------------------------------
+
+split_bin(Bin) ->
+ split_bin(0, Bin).
+
+split_bin(N, Bin) ->
+ case Bin of
+ <<Line:N/binary, "\r\n", Rest/binary>> ->
+ [Line | split_bin(0, Rest)];
+ <<Line:N/binary, "\n", Rest/binary>> ->
+ [Line | split_bin(0, Rest)];
+ <<Line:N/binary>> ->
+ [Line];
+ _ ->
+ split_bin(N+1, Bin)
+ end.
+
+decode_file(Bin, Passwd) ->
+ decode_file(Bin, [], [Passwd]).
+
+decode_file([<<"-----BEGIN CERTIFICATE REQUEST-----", _/binary>>|Rest], Ens, Info) ->
+ decode_file2(Rest, [], Ens, cert_req, Info);
+decode_file([<<"-----BEGIN CERTIFICATE-----", _/binary>>|Rest], Ens, Info) ->
+ decode_file2(Rest, [], Ens, cert, Info);
+decode_file([<<"-----BEGIN RSA PRIVATE KEY-----", _/binary>>|Rest], Ens, Info) ->
+ decode_file2(Rest, [], Ens, rsa_private_key, Info);
+decode_file([<<"-----BEGIN DSA PRIVATE KEY-----", _/binary>>|Rest], Ens, Info) ->
+ decode_file2(Rest, [], Ens, dsa_private_key, Info);
+decode_file([<<"-----BEGIN DH PARAMETERS-----", _/binary>>|Rest], Ens, Info) ->
+ decode_file2(Rest, [], Ens, dh_params, Info);
+decode_file([_|Rest], Ens, Info) ->
+ decode_file(Rest, Ens, Info);
+decode_file([], Ens, _Info) ->
+ {ok, lists:reverse(Ens)}.
+
+decode_file2([<<"Proc-Type: 4,ENCRYPTED", _/binary>>| Rest0], RLs, Ens, Tag, Info0) ->
+ [InfoLine|Rest] = Rest0,
+ Info = dek_info(InfoLine, Info0),
+ decode_file2(Rest, RLs, Ens, Tag, Info);
+decode_file2([<<"-----END", _/binary>>| Rest], RLs, Ens, Tag, Info0) ->
+ Cs = erlang:iolist_to_binary(lists:reverse(RLs)),
+ Bin = base64:mime_decode(Cs),
+ case Info0 of
+ [Password, Cipher, SaltHex | Info1] ->
+ Salt = unhex(SaltHex),
+ Enc = {Cipher, Salt},
+ Decoded = decode_key(Bin, Password, Cipher, Salt),
+ decode_file(Rest, [{Tag, Decoded, Enc}| Ens], Info1);
+ _ ->
+ decode_file(Rest, [{Tag, Bin, not_encrypted}| Ens], Info0)
+ end;
+decode_file2([L|Rest], RLs, Ens, Tag, Info0) ->
+ decode_file2(Rest, [L|RLs], Ens, Tag, Info0);
+decode_file2([], _, Ens, _, _) ->
+ {ok, lists:reverse(Ens)}.
+
+%% TODO Support same as decode_file
+encode_file(Ds) ->
+ lists:map(
+ fun({cert, Bin}) ->
+ %% PKIX (X.509)
+ ["-----BEGIN CERTIFICATE-----\n",
+ b64encode_and_split(Bin),
+ "-----END CERTIFICATE-----\n\n"];
+ ({cert_req, Bin}) ->
+ %% PKCS#10
+ ["-----BEGIN CERTIFICATE REQUEST-----\n",
+ b64encode_and_split(Bin),
+ "-----END CERTIFICATE REQUEST-----\n\n"];
+ ({rsa_private_key, Bin}) ->
+ %% PKCS#?
+ ["XXX Following key assumed not encrypted\n",
+ "-----BEGIN RSA PRIVATE KEY-----\n",
+ b64encode_and_split(Bin),
+ "-----END RSA PRIVATE KEY-----\n\n"]
+ end, Ds).
+
+dek_info(Line0, Info) ->
+ Line = binary_to_list(Line0),
+ [_, DekInfo0] = string:tokens(Line, ": "),
+ DekInfo1 = string:tokens(DekInfo0, ",\n"),
+ Info ++ DekInfo1.
+
+unhex(S) ->
+ unhex(S, []).
+
+unhex("", Acc) ->
+ lists:reverse(Acc);
+unhex([D1, D2 | Rest], Acc) ->
+ unhex(Rest, [erlang:list_to_integer([D1, D2], 16) | Acc]).
+
+decode_key(Data, no_passwd, _Alg, _Salt) ->
+ Data;
+decode_key(Data, Password, "DES-CBC", Salt) ->
+ Key = password_to_key(Password, Salt, 8),
+ IV = Salt,
+ crypto:des_cbc_decrypt(Key, IV, Data);
+decode_key(Data, Password, "DES-EDE3-CBC", Salt) ->
+ Key = password_to_key(Password, Salt, 24),
+ IV = Salt,
+ <<Key1:8/binary, Key2:8/binary, Key3:8/binary>> = Key,
+ crypto:des_ede3_cbc_decrypt(Key1, Key2, Key3, IV, Data).
+
+password_to_key(Data, Salt, KeyLen) ->
+ <<Key:KeyLen/binary, _/binary>> =
+ password_to_key(<<>>, Data, Salt, KeyLen, <<>>),
+ Key.
+
+password_to_key(_, _, _, Len, Acc) when Len =< 0 ->
+ Acc;
+password_to_key(Prev, Data, Salt, Len, Acc) ->
+ M = crypto:md5([Prev, Data, Salt]),
+ password_to_key(M, Data, Salt, Len - size(M), <<Acc/binary, M/binary>>).
+
+b64encode_and_split(Bin) ->
+ split_lines(base64:encode(Bin)).
+
+split_lines(<<Text:?ENCODED_LINE_LENGTH/binary, Rest/binary>>) ->
+ [Text, $\n | split_lines(Rest)];
+split_lines(Bin) ->
+ [Bin, $\n].
+