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Submitted on behalf of @luos: Implement fallback secret #15

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Merged
merged 1 commit into from
May 2, 2022
Merged

Submitted on behalf of @luos: Implement fallback secret #15

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7 changes: 6 additions & 1 deletion src/credentials_obfuscation.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@
-export([enabled/0, cipher/0, hash/0, iterations/0, secret/0]).

%% API
-export([set_secret/1, encrypt/1, decrypt/1, refresh_config/0]).
-export([set_secret/1, set_fallback_secret/1, encrypt/1, decrypt/1, refresh_config/0]).

-spec enabled() -> boolean().
enabled() ->
Expand All @@ -37,6 +37,11 @@ secret() ->
set_secret(Secret) when is_binary(Secret) ->
ok = credentials_obfuscation_svc:set_secret(Secret).


-spec set_fallback_secret(binary()) -> ok.
set_fallback_secret(Secret) when is_binary(Secret) ->
ok = credentials_obfuscation_svc:set_fallback_secret(Secret).

-spec encrypt(term()) -> {plaintext, term()} | {encrypted, binary()}.
encrypt(none) -> none;
encrypt(undefined) -> undefined;
Expand Down
61 changes: 53 additions & 8 deletions src/credentials_obfuscation_svc.erl
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Expand Up @@ -16,6 +16,7 @@
get_config/1,
refresh_config/0,
set_secret/1,
set_fallback_secret/1,
encrypt/1,
decrypt/1]).

Expand All @@ -31,9 +32,11 @@
cipher :: atom(),
hash :: atom(),
iterations :: non_neg_integer(),
secret :: binary() | '$pending-secret'}).
secret :: binary() | '$pending-secret',
fallback_secret :: binary() | undefined}).

-define(TIMEOUT, 30000).
-define(VALUE_TAG, credentials_obfuscation).

%%%===================================================================
%%% API functions
Expand All @@ -54,8 +57,13 @@ refresh_config() ->
set_secret(Secret) when is_binary(Secret) ->
gen_server:call(?MODULE, {set_secret, Secret}).

-spec set_fallback_secret(binary()) -> ok.
set_fallback_secret(Secret) when is_binary(Secret) ->
gen_server:call(?MODULE, {set_fallback_secret, Secret}).


-spec encrypt(term()) -> {plaintext, term()} | {encrypted, binary()}.
encrypt(Term) ->
encrypt(Term) when is_binary(Term); is_list(Term) ->
try
gen_server:call(?MODULE, {encrypt, Term}, ?TIMEOUT)
catch exit:{timeout, _} ->
Expand Down Expand Up @@ -99,19 +107,42 @@ handle_call({encrypt, Term}, _From, #state{enabled=false}=State) ->
handle_call({encrypt, Term}, _From, #state{cipher=Cipher,
hash=Hash,
iterations=Iterations,
secret=Secret}=State) ->
Encrypted = credentials_obfuscation_pbe:encrypt(Cipher, Hash, Iterations, Secret, Term),
{reply, Encrypted, State};
secret=Secret} = State) ->
% We need to wrap the data in a tuple to be able to say if the decryption was
% successful or not. We may just receive junk data if the secret is incorrect
% upon decryption.
ClearText = {?VALUE_TAG, to_binary(Term)},
Encrypted = credentials_obfuscation_pbe:encrypt_term(Cipher, Hash, Iterations, Secret, ClearText),
case Encrypted of
{plaintext, _} ->
{reply, {plaintext, Term}, State};
_ -> {reply, Encrypted, State}
end;
handle_call({decrypt, Term}, _From, #state{enabled=false}=State) ->
{reply, Term, State};
handle_call({decrypt, {plaintext, Term}}, _From, State) ->
{reply, Term, State};
handle_call({decrypt, Term}, _From, #state{cipher=Cipher,
hash=Hash,
iterations=Iterations,
secret=Secret}=State) ->
Decrypted = credentials_obfuscation_pbe:decrypt(Cipher, Hash, Iterations, Secret, Term),
{reply, Decrypted, State};
secret=Secret,
fallback_secret=FallbackSecret}=State) ->
case try_decrypt(Cipher, Hash, Iterations, Secret, Term) of
{ok, Decrypted} ->
{reply, Decrypted, State};
{error, _E} ->
case try_decrypt(Cipher, Hash, Iterations, FallbackSecret, Term) of
{ok, Decrypted2} ->
{reply, Decrypted2, State};
_E2 ->
{reply, Term, State}
end
end;
handle_call({set_secret, Secret}, _From, State0) ->
State1 = State0#state{secret = Secret},
{reply, ok, State1};
handle_call({set_fallback_secret, Secret}, _From, State0) ->
State1 = State0#state{fallback_secret = Secret},
{reply, ok, State1}.

handle_cast(_Message, State) ->
Expand Down Expand Up @@ -163,3 +194,17 @@ check(Cipher, Hash, Iterations) ->
E = credentials_obfuscation_pbe:encrypt(Cipher, Hash, Iterations, TempSecret, Value),
Value = credentials_obfuscation_pbe:decrypt(Cipher, Hash, Iterations, TempSecret, E),
ok.

try_decrypt(Cipher, Hash, Iterations, Secret, Term) ->
try
{?VALUE_TAG, Decrypted} =
credentials_obfuscation_pbe:decrypt_term(Cipher, Hash, Iterations, Secret, Term),
{ok, Decrypted}
catch
ErrorType:Error:_Stacktrace ->
{error, {ErrorType, Error}}
end.

% currently the callers may rely on this process converting strings to binary
to_binary(Term) when is_list(Term) -> erlang:list_to_binary(Term);
to_binary(Term) when is_binary(Term) -> Term.
31 changes: 31 additions & 0 deletions test/credentials_obfuscation_SUITE.erl
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Expand Up @@ -15,6 +15,8 @@ all() -> [encrypt_decrypt,
encrypt_decrypt_char_list_value,
use_predefined_secret,
use_cookie_as_secret,
change_of_secret_returns_passed_in_data,
fallback_secret,
encryption_happens_only_when_secret_available,
change_default_cipher,
disabled,
Expand Down Expand Up @@ -102,6 +104,35 @@ use_cookie_as_secret(_Config) ->
ok = net_kernel:stop(),
ok.

%% change of secret should not crash the credentials_obfuscation_svc process
change_of_secret_returns_passed_in_data(_Config) ->
Secret1 = crypto:strong_rand_bytes(128),
Secret2 = crypto:strong_rand_bytes(128),
Uri = <<"amqp://super:secret@localhost:5672">>,
ok = credentials_obfuscation:set_secret(Secret1),
Encrypted = credentials_obfuscation:encrypt(Uri),
ok = credentials_obfuscation:set_secret(Secret2),
?assertEqual(Encrypted, credentials_obfuscation:decrypt(Encrypted)),
ok.

fallback_secret(_Config) ->
Secret1 = crypto:strong_rand_bytes(128),
Secret2 = crypto:strong_rand_bytes(128),
Uri = <<"amqp://super:secret@localhost:5672">>,
ok = credentials_obfuscation:set_secret(Secret1),
Encrypted = credentials_obfuscation:encrypt(Uri),

ok = credentials_obfuscation:set_secret(Secret2),
Encrypted2 = credentials_obfuscation:encrypt(Uri),

?assertEqual(Encrypted, credentials_obfuscation:decrypt(Encrypted)),

ok = credentials_obfuscation:set_fallback_secret(Secret1),

?assertEqual(Uri, credentials_obfuscation:decrypt(Encrypted)),
?assertEqual(Uri, credentials_obfuscation:decrypt(Encrypted2)),
ok.

encryption_happens_only_when_secret_available(_Config) ->
_ = net_kernel:stop(),
Uri = <<"amqp://super:secret@localhost:5672">>,
Expand Down