%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2003-2009. 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%
%%
%%
-module(ssl_pem).
%%% Purpose: Reading and writing of PEM type encoded files for SSL.
%% NB write_file/2 is only preliminary.
%% 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.
-export([read_file/1, read_file/2, write_file/2]).
%% Read a PEM file and return each decoding as a binary.
read_file(File) ->
read_file(File, no_passwd).
read_file(File, Passwd) ->
{ok, Fd} = file:open(File, [read]),
Result = decode_file(Fd, Passwd),
file:close(Fd),
Result.
decode_file(Fd, Passwd) ->
decode_file(Fd, [], [], notag, [Passwd]).
decode_file(Fd, _RLs, Ens, notag, Info) ->
case io:get_line(Fd, "") of
"-----BEGIN CERTIFICATE REQUEST-----" ++ _ ->
decode_file(Fd, [], Ens, cert_req, Info);
"-----BEGIN CERTIFICATE-----" ++ _ ->
decode_file(Fd, [], Ens, cert, Info);
"-----BEGIN RSA PRIVATE KEY-----" ++ _ ->
decode_file(Fd, [], Ens, rsa_private_key, Info);
eof ->
{ok, lists:reverse(Ens)};
_ ->
decode_file(Fd, [], Ens, notag, Info)
end;
decode_file(Fd, RLs, Ens, Tag, Info0) ->
case io:get_line(Fd, "") of
"Proc-Type: 4,ENCRYPTED"++_ ->
Info = dek_info(Fd, Info0),
decode_file(Fd, RLs, Ens, Tag, Info);
"-----END" ++ _ -> % XXX sloppy
Cs = lists:flatten(lists:reverse(RLs)),
Bin = ssl_base64:join_decode(Cs),
case Info0 of
[Password, Cipher, SaltHex | Info1] ->
Decoded = decode_key(Bin, Password, Cipher, unhex(SaltHex)),
decode_file(Fd, [], [{Tag, Decoded}| Ens], notag, Info1);
_ ->
decode_file(Fd, [], [{Tag, Bin}| Ens], notag, Info0)
end;
eof ->
{ok, lists:reverse(Ens)};
L ->
decode_file(Fd, [L|RLs], Ens, Tag, Info0)
end.
dek_info(Fd, Info) ->
Line = io:get_line(Fd, ""),
[_, 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, 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).
write_file(File, Ds) ->
file:write_file(File, encode_file(Ds)).
encode_file(Ds) ->
[encode_file_1(D) || D <- Ds].
encode_file_1({cert, Bin}) ->
%% PKIX (X.509)
["-----BEGIN CERTIFICATE-----\n",
ssl_base64:encode_split(Bin),
"-----END CERTIFICATE-----\n\n"];
encode_file_1({cert_req, Bin}) ->
%% PKCS#10
["-----BEGIN CERTIFICATE REQUEST-----\n",
ssl_base64:encode_split(Bin),
"-----END CERTIFICATE REQUEST-----\n\n"];
encode_file_1({rsa_private_key, Bin}) ->
%% PKCS#?
["XXX Following key assumed not encrypted\n",
"-----BEGIN RSA PRIVATE KEY-----\n",
ssl_base64:encode_split(Bin),
"-----END RSA PRIVATE KEY-----\n\n"].
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 - byte_size(M), <<Acc/binary, M/binary>>).
