Add keypair encoding, fix seckey size checks

src/gmser_api_encoder.erl

@@ -13,8 +13,15 @@
          safe_decode/2,
          byte_size_for_type/1]).
 
+-export([encode_keypair/1,
+         safe_decode_keypair/1]).
+
+-ifdef(TEST).
+-export([encode_/2]).   %% Encode without size checks
+-endif.
+
 -export_type([encoded/0,
-             known_type/0]).
+              known_type/0]).
 
 -type known_type() :: key_block_hash
                     | micro_block_hash
@@ -53,14 +60,66 @@
 -type payload() :: binary().
 -type encoded() :: binary().
 
+-type keypair() :: #{public := <<_:(32*8)>>, secret := <<_:(64*8)>>}.
+-type encoded_keypair() :: #{binary() => binary()}.
+
+-export_type([ keypair/0
+             , encoded_keypair/0 ]).
+
 -define(BASE58, 1).
 -define(BASE64, 2).
 
+-spec encode_keypair(keypair()) -> encoded_keypair().
+encode_keypair(#{public := Pub, secret := Sec}) ->
+    case Sec of
+        <<Seed:32/binary, Pub1:32/binary>> when Pub1 =:= Pub ->
+            #{ <<"pub">> => encode(account_pubkey, Pub)
+             , <<"priv">> => encode(account_seckey, Seed) };
+        _ ->
+            erlang:error(invalid_keypair)
+    end.
+
+-spec safe_decode_keypair(encoded_keypair()) -> {'ok', keypair()} | {'error', atom()}.
+safe_decode_keypair(#{<<"pub">> := EncPub, <<"priv">> := EncPriv}) ->
+    case safe_decode(account_pubkey, EncPub) of
+        {ok, Pub} ->
+            case safe_decode(account_seckey, EncPriv) of
+                {ok, Seed} when byte_size(Seed) =:= 32 ->
+                    case enacl:sign_seed_keypair(Seed) of
+                        #{public := Pub, secret := _} = KP ->
+                            {ok, KP};
+                        _ ->
+                            {error, illegal_encoding}
+                    end;
+                {ok, <<Seed:32/binary, Pub:32/binary>>} ->
+                    case enacl:sign_seed_keypair(Seed) of
+                        #{public := Pub} = KP ->
+                            {ok, KP};
+                        _ ->
+                            {error, illegal_encoding}
+                    end;
+                {ok, _} ->
+                    {error, illegal_encoding};
+                {error, _} = Error1 ->
+                    Error1
+            end;
+        Error ->
+            Error
+    end.
+
 -spec encode(known_type(), payload() | gmser_id:id()) -> encoded().
 encode(id_hash, Payload) ->
     {IdType, Val} = gmser_id:specialize(Payload),
     encode(id2type(IdType), Val);
 encode(Type, Payload) ->
+    case type_size_check(Type, Payload) of
+        ok ->
+            encode_(Type, Payload);
+        {error, Reason} ->
+            erlang:error(Reason)
+    end.
+
+encode_(Type, Payload) ->
     Pfx = type2pfx(Type),
     Enc = case type2enc(Type) of
               ?BASE58 -> base58_check(Payload);
@@ -68,6 +127,7 @@ encode(Type, Payload) ->
           end,
     <<Pfx/binary, "_", Enc/binary>>.
 
+
 -spec decode(binary()) -> {known_type(), payload()}.
 decode(Bin0) ->
     case split(Bin0) of
@@ -83,6 +143,13 @@ decode(Bin0) ->
             erlang:error(missing_prefix)
     end.
 
+type_size_check(account_seckey, Bin) ->
+    case byte_size(Bin) of
+        Sz when Sz =:= 32; Sz =:= 64 ->
+            ok;
+        _ ->
+            {error, incorrect_size}
+    end;
 type_size_check(Type, Bin) ->
     case byte_size_for_type(Type) of
         not_applicable -> ok;