%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2011-2011. 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: Implements Password Based Encryption PKCS-5, RFC-2898
-module(pubkey_pbe).
-include("public_key.hrl").
-export([encode/4, decode/4, decrypt_parameters/1]).
-export([pbdkdf1/4, pbdkdf2/6]).
-define(DEFAULT_SHA_MAC_KEYLEN, 20).
-define(ASN1_OCTET_STR_TAG, 4).
-define(IV_LEN, 8).
%%====================================================================
%% Internal application API
%%====================================================================
pbdkdf2(Password, Salt, Count, DerivedKeyLen, Prf, PrfOutputLen)->
NumBlocks = ceiling(DerivedKeyLen / PrfOutputLen),
NumLastBlockOctets = DerivedKeyLen - (NumBlocks - 1) * PrfOutputLen ,
blocks(NumBlocks, NumLastBlockOctets, 1, Password, Salt, Count, Prf, PrfOutputLen, <<>>).
encode(Data, Password, "DES-CBC" = Cipher, KeyDevParams) ->
{Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams),
crypto:des_cbc_encrypt(Key, IV, Data);
encode(Data, Password, "DES-EDE3-CBC" = Cipher, KeyDevParams) ->
{Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams),
<<Key1:8/binary, Key2:8/binary, Key3:8/binary>> = Key,
crypto:des_ede3_cbc_encrypt(Key1, Key2, Key3, IV, Data);
encode(Data, Password, "RC2-CBC" = Cipher, KeyDevParams) ->
{Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams),
crypto:rc2_cbc_encrypt(Key, IV, Data).
decode(Data, Password,"DES-CBC"= Cipher, KeyDevParams) ->
{Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams),
crypto:des_cbc_decrypt(Key, IV, Data);
decode(Data, Password,"DES-EDE3-CBC" = Cipher, KeyDevParams) ->
{Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams),
<<Key1:8/binary, Key2:8/binary, Key3:8/binary>> = Key,
crypto:des_ede3_cbc_decrypt(Key1, Key2, Key3, IV, Data);
decode(Data, Password,"RC2-CBC"= Cipher, KeyDevParams) ->
{Key, IV} = password_to_key_and_iv(Password, Cipher, KeyDevParams),
crypto:rc2_cbc_decrypt(Key, IV, Data).
%%--------------------------------------------------------------------
-spec pbdkdf1(string(), iodata(), integer(), atom()) -> binary().
%%
%% Description: Implements password based decryption key derive function 1.
%% Exported mainly for testing purposes.
%%--------------------------------------------------------------------
pbdkdf1(_, _, 0, Acc) ->
Acc;
pbdkdf1(Password, Salt, Count, Hash) ->
Result = crypto:Hash([Password, Salt]),
do_pbdkdf1(Result, Count-1, Result, Hash).
%%--------------------------------------------------------------------
-spec pbdkdf2(string(), iodata(), integer(), integer(), fun(), integer())
-> binary().
%%
%% Description: Implements password based decryption key derive function 2.
%% Exported mainly for testing purposes.
%%--------------------------------------------------------------------
pbdkdf2(Password, Salt, Count, DerivedKeyLen, Prf, PrfOutputLen)->
NumBlocks = ceiling(DerivedKeyLen / PrfOutputLen),
NumLastBlockOctets = DerivedKeyLen - (NumBlocks - 1) * PrfOutputLen ,
blocks(NumBlocks, NumLastBlockOctets, 1, Password, Salt,
Count, Prf, PrfOutputLen, <<>>).
%%--------------------------------------------------------------------
-spec decrypt_parameters(#'EncryptedPrivateKeyInfo_encryptionAlgorithm'{}) ->
{Cipher::string(), #'PBES2-params'{}}.
%%
%% Description: Performs ANS1-decoding of encryption parameters.
%%--------------------------------------------------------------------
decrypt_parameters(#'EncryptedPrivateKeyInfo_encryptionAlgorithm'{
algorithm = Oid, parameters = Param}) ->
decrypt_parameters(Oid, Param).
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
password_to_key_and_iv(Password, Cipher, {salt, Salt}) ->
KeyLen = derived_key_length(Cipher, undefined),
<<Key:KeyLen/binary, _/binary>> =
pem_encrypt(<<>>, Password, Salt, ceiling(KeyLen div 16), <<>>, md5),
%% Old PEM encryption does not use standard encryption method
%% pbdkdf1 and uses then salt as IV
{Key, Salt}.
password_to_key_and_iv(Password, _, #'PBES2-params'{} = Params) ->
{Salt, ItrCount, KeyLen, PseudoRandomFunction, PseudoOtputLen, IV} =
key_derivation_params(Params),
<<Key:KeyLen/binary, _/binary>> =
pbdkdf2(Password, Salt, ItrCount, KeyLen, PseudoRandomFunction, PseudoOtputLen),
{Key, IV}.
pem_encrypt(_, _, _, 0, Acc, _) ->
Acc;
pem_encrypt(Prev, Password, Salt, Count, Acc, Hash) ->
Result = crypto:Hash([Prev, Password, Salt]),
pem_encrypt(Result, Password, Salt, Count-1 , <<Acc/binary, Result/binary>>, Hash).
do_pbdkdf1(_, 0, Acc, _) ->
Acc;
do_pbdkdf1(Prev, Count, Acc, Hash) ->
Result = crypto:Hash(Prev),
do_pbdkdf1(Result, Count-1 , <<Result/binary, Acc/binary>>, Hash).
iv(#'PBES2-params_encryptionScheme'{algorithm = Algo,
parameters = ASNIV}) when (Algo == ?'desCBC') or
(Algo == ?'des-EDE3-CBC') ->
%% This is an so called open ASN1-type that in this
%% case will be an octet-string of length 8
<<?ASN1_OCTET_STR_TAG, ?IV_LEN, IV:?IV_LEN/binary>> = ASNIV,
IV;
iv(#'PBES2-params_encryptionScheme'{algorithm = ?'rc2CBC',
parameters = ASN1IV}) ->
{ok, #'RC2-CBC-Parameter'{iv = IV}} = 'PKCS-FRAME':decode('RC2-CBC-Parameter', ASN1IV),
iolist_to_binary(IV).
blocks(1, N, Index, Password, Salt, Count, Prf, PrfLen, Acc) ->
<<XorSum:N/binary, _/binary>> = xor_sum(Password, Salt, Count, Index, Prf, PrfLen),
<<Acc/binary, XorSum/binary>>;
blocks(NumBlocks, N, Index, Password, Salt, Count, Prf, PrfLen, Acc) ->
XorSum = xor_sum(Password, Salt, Count, Index, Prf, PrfLen),
blocks(NumBlocks -1, N, Index +1, Password, Salt, Count, Prf, PrfLen, <<Acc/binary, XorSum/binary>>).
xor_sum(Password, Salt, Count, Index, Prf, PrfLen) ->
Result = Prf(Password, [Salt,<<Index:32/unsigned-big-integer>>], PrfLen),
do_xor_sum(Prf, PrfLen, Result, Password, Count-1, Result).
do_xor_sum(_, _, _, _, 0, Acc) ->
Acc;
do_xor_sum(Prf, PrfLen, Prev, Password, Count, Acc)->
Result = Prf(Password, Prev, PrfLen),
do_xor_sum(Prf, PrfLen, Result, Password, Count-1, crypto:exor(Acc, Result)).
decrypt_parameters(?'id-PBES2', DekParams) ->
{ok, Params} = 'PKCS-FRAME':decode('PBES2-params', DekParams),
{cipher(Params#'PBES2-params'.encryptionScheme), Params}.
key_derivation_params(#'PBES2-params'{keyDerivationFunc = KeyDerivationFunc,
encryptionScheme = EncScheme}) ->
#'PBES2-params_keyDerivationFunc'{algorithm = ?'id-PBKDF2',
parameters =
#'PBKDF2-params'{salt = {specified, OctetSalt},
iterationCount = Count,
keyLength = Length,
prf = Prf}} = KeyDerivationFunc,
#'PBES2-params_encryptionScheme'{algorithm = Algo} = EncScheme,
{PseudoRandomFunction, PseudoOtputLen} = pseudo_random_function(Prf),
KeyLen = derived_key_length(Algo, Length),
{iolist_to_binary(OctetSalt), Count, KeyLen, PseudoRandomFunction, PseudoOtputLen, iv(EncScheme)}.
%% This function currently matches a tuple that ougth to be the value ?'id-hmacWithSHA1,
%% but we need some kind of ASN1-fix for this.
pseudo_random_function(#'PBKDF2-params_prf'{algorithm = {_,_, _,'id-hmacWithSHA1'}}) ->
{fun crypto:sha_mac/3, pseudo_output_length(?'id-hmacWithSHA1')}.
pseudo_output_length(?'id-hmacWithSHA1') ->
?DEFAULT_SHA_MAC_KEYLEN.
derived_key_length(_, Len) when is_integer(Len) ->
Len;
derived_key_length(Cipher,_) when (Cipher == ?'desCBC') or (Cipher == "DES-CBC") ->
8;
derived_key_length(Cipher,_) when (Cipher == ?'rc2CBC') or (Cipher == "RC2-CBC") ->
16;
derived_key_length(Cipher,_) when (Cipher == ?'des-EDE3-CBC') or (Cipher == "DES-EDE3-CBC") ->
24.
cipher(#'PBES2-params_encryptionScheme'{algorithm = ?'desCBC'}) ->
"DES-CBC";
cipher(#'PBES2-params_encryptionScheme'{algorithm = ?'des-EDE3-CBC'}) ->
"DES-EDE3-CBC";
cipher(#'PBES2-params_encryptionScheme'{algorithm = ?'rc2CBC'}) ->
"RC2-CBC".
ceiling(Float) ->
erlang:round(Float + 0.5).
