Add binary signatures

src/hz.erl

@@ -73,8 +73,8 @@
          decode_bytearray_fate/1, decode_bytearray/2,
          spend/5, spend/10,
          sign_tx/2, sign_tx/3,
-         sign_message/2,
-         verify_signature/3]).
+         sign_message/2, verify_signature/3,
+         sign_binary/2, verify_bin_signature/3]).
 
 
 %%% Types
@@ -2398,7 +2398,7 @@ spend3(DSenderID,
          Sig     :: binary().
 
 sign_message(Message, SecKey) ->
-    Prefix = <<"Gajumaru Signed Message:\n">>,
+    Prefix = message_sig_prefix(),
     {ok, PSize} = vencode(byte_size(Prefix)),
     {ok, MSize} = vencode(byte_size(Message)),
     Smashed = iolist_to_binary([PSize, Prefix, MSize, Message]),
@@ -2407,7 +2407,7 @@ sign_message(Message, SecKey) ->
 
 
 -spec verify_signature(Sig, Message, PubKey) -> Result
-    when Sig     :: binary(),
+    when Sig     :: string(), % base64 encoded signature,
          Message :: iodata(),
          PubKey  :: pubkey(),
          Result  :: {ok, Outcome :: boolean()}
@@ -2432,7 +2432,7 @@ verify_signature2(Sig, Message, PK) ->
     % the user from accidentally signing a transaction disguised as a message.
     %
     % Salt the message then hash with blake2b.
-    Prefix = <<"Gajumaru Signed Message:\n">>,
+    Prefix = message_sig_prefix(),
     {ok, PSize} = vencode(byte_size(Prefix)),
     {ok, MSize} = vencode(byte_size(Message)),
     Smashed = iolist_to_binary([PSize, Prefix, MSize, Message]),
@@ -2442,6 +2442,7 @@ verify_signature2(Sig, Message, PK) ->
     Result = ecu_eddsa:sign_verify_detached(Signature, Hashed, PK),
     {ok, Result}.
 
+message_sig_prefix() -> <<"Gajumaru Signed Message:\n">>.
 
 % This is Bitcoin's variable-length unsigned integer encoding
 % See: https://en.bitcoin.it/wiki/Protocol_documentation#Variable_length_integer
@@ -2469,6 +2470,42 @@ eu(N, Size) ->
     <<Bytes/binary, ExtraZeros/binary>>.
 
 
+-spec sign_binary(Binary, SecKey) -> Sig
+    when Binary :: binary(),
+         SecKey :: binary(),
+         Sig    :: binary().
+
+sign_binary(Binary, SecKey) ->
+    Prefix = binary_sig_prefix(),
+    Target = <<Prefix/binary, Binary/binary>>,
+    {ok, Hash} = eblake2:blake2b(32, Target),
+    ecu_eddsa:sign_detached(Hash, SecKey).
+
+
+-spec verify_bin_signature(Sig, Binary, PubKey) -> Result
+    when Sig     :: string(), % base64 encoded signature,
+         Binary  :: binary(),
+         PubKey  :: pubkey(),
+         Result  :: {ok, Outcome :: boolean()}
+                  | {error, Reason :: term()}.
+
+verify_bin_signature(Sig, Binary, PubKey) ->
+    case gmser_api_encoder:decode(PubKey) of
+        {account_pubkey, PK} -> verify_bin_signature2(Sig, Binary, PK);
+        Other                -> {error, {bad_key, Other}}
+    end.
+
+verify_bin_signature2(Sig, Binary, PK) ->
+    Prefix = binary_sig_prefix(),
+    Target = <<Prefix/binary, Binary/binary>>,
+    {ok, Hash} = eblake2:blake2b(32, Target),
+    Signature = base64:decode(Sig),
+    Result = ecu_eddsa:sign_verify_detached(Signature, Hash, PK),
+    {ok, Result}.
+
+binary_sig_prefix() -> <<"Gajumaru Signed Binary:">>.
+
+
 %%% Debug functionality
 
 % debug_network() ->