From 4f8b06713fc4e46641a5d01bb8f9c056c7aca928 Mon Sep 17 00:00:00 2001
From: Sean Hinde <sean.hinde@mac.com>
Date: Fri, 13 Jan 2023 11:31:14 +0100
Subject: [PATCH] Small fixes

---
 c_src/ecrecover.c     | 9 ++++++---
 default.nix           | 4 ----
 src/ecrecover.app.src | 3 ++-
 src/ecrecover.erl     | 9 ++-------
 4 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/c_src/ecrecover.c b/c_src/ecrecover.c
index 9ce2289..ad9abba 100644
--- a/c_src/ecrecover.c
+++ b/c_src/ecrecover.c
@@ -1,3 +1,6 @@
+// Very specific NIF just for key recovery.
+// Partly from https://github.com/mbrix/libsecp256k1
+
 #include "erl_nif.h"
 #include "secp256k1_recovery.h"
 
@@ -17,7 +20,7 @@ static ERL_NIF_TERM ok_result(ErlNifEnv* env, ERL_NIF_TERM *r)
 static ERL_NIF_TERM
 recover(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 {
-  ERL_NIF_TERM r;
+    ERL_NIF_TERM r;
 	ErlNifBinary message, csignature;
 	int result;
     int compressed = SECP256K1_EC_UNCOMPRESSED;
@@ -36,11 +39,11 @@ recover(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
     }
 
     if (!enif_get_int(env, argv[2], &recid)) {
-		return error_result(env, "Recovery id invalid 0-3");
+		return error_result(env, "Recovery id invalid not integer 0-3");
 	}
 
     if (recid < 0 || recid > 3) {
-		error_result(env, "Recovery id invalid 0-3x");
+		error_result(env, "Recovery id invalid 0-3");
 	}
 
     result = secp256k1_ecdsa_recoverable_signature_parse_compact(ctx, &signature, csignature.data, recid);
diff --git a/default.nix b/default.nix
index 3e31823..e5e67d7 100644
--- a/default.nix
+++ b/default.nix
@@ -11,10 +11,6 @@ in {
       stable.stdenv
       ## erlang
       stable.erlangR21 # OTP 21.3.5.2
-      ## rust, required for building the NIF
-      stable.rustc
-      stable.cargo
-      stable.cmake
     ];
   };
 }
diff --git a/src/ecrecover.app.src b/src/ecrecover.app.src
index 9c7a456..bab7436 100644
--- a/src/ecrecover.app.src
+++ b/src/ecrecover.app.src
@@ -4,7 +4,8 @@
   {registered, []},
   {applications,
    [kernel,
-    stdlib
+    stdlib,
+    sha3
    ]},
   {env,[]},
   {modules, []},
diff --git a/src/ecrecover.erl b/src/ecrecover.erl
index 3ed9488..314ff23 100644
--- a/src/ecrecover.erl
+++ b/src/ecrecover.erl
@@ -1,7 +1,5 @@
 -module(ecrecover).
 
-%% https://github.com/mbrix/libsecp256k1
-
 %% API
 -export([recover/2, recover/3]).
 
@@ -11,10 +9,6 @@
 
 %%=============================================================================
 %% NIF API
-%% GoodMsg1 = <<71,23,50,133,168,215,52,30,94,151,47,198,119,40,99,132,248,2,248,239,66,165,236,95,3,187,250,37,76,176,31,173>>.
-%% GoodSig1_v = <<27,101,10,207,157,63,95,10,44,121,151,118,161,37,67,85,213,244,6,23,98,162,55,57,106,153,160,224,227,252,43,205,103,41,81,74,13,172,178,230,35,172,74,189,21,124,177,129,99,255,148,34,128,219,77,92,170,214,109,223,148,27,161,46,3>>.
-%% ecrecover:recover(<<71,23,50,133,168,215,52,30,94,151,47,198,119,40,99,132,248,2,248,239,66,165,236,95,3,187,250,37,76,176,31,173>>, <<27,101,10,207,157,63,95,10,44,121,151,118,161,37,67,85,213,244,6,23,98,162,55,57,106,153,160,224,227,252,43,205,103,41,81,74,13,172,178,230,35,172,74,189,21,124,177,129,99,255,148,34,128,219,77,92,170,214,109,223,148,27,161,46,3>>).
-%% 
 
 load() ->
     EbinDir = filename:dirname(code:which(?MODULE)),
@@ -29,6 +23,7 @@ not_loaded(Line) ->
 %%=============================================================================
 %% External API
 
+-spec recover(<<_:(32*8)>>, <<_:(65*8)>>) -> <<_:(32*8)>>.
 recover(Hash, <<V, Sig:64/binary>>) when V == 27; V == 28 ->
     RecId = V - 27,
     case recover(Hash, Sig, RecId) of
@@ -41,7 +36,7 @@ recover(Hash, <<V, Sig:64/binary>>) when V == 27; V == 28 ->
 recover(_Hash, _VSig) ->
     <<0:256>>.
 
--spec recover(<<_:(32*8)>>, <<_:(65*8)>>, integer()) -> <<_:(32*8)>>.
+-spec recover(<<_:(32*8)>>, <<_:(64*8)>>, integer()) -> <<_:(32*8)>>.
 recover(_Hash, _Sig, _RecId) ->
     not_loaded(?LINE).