add tiny secp256k1 native binding

.gitignore

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+build/
+coverage/
+node_modules/

.gitmodules

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+[submodule "native/secp256k1"]
+	path = native/secp256k1
+	url = git@github.com:bitcoin-core/secp256k1.git

binding.gyp

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+{
+  "targets": [{
+    "target_name": "secp256k1",
+    "variables": {
+      "conditions": [
+        [
+          "OS=='win'", {
+            "with_gmp%": "false"
+          }, {
+            "with_gmp%": "<!(scripts/checklib gmpxx && scripts/checklib gmp)"
+          }
+        ]
+      ]
+    },
+    "sources": [
+      "./native/addon.cpp",
+      "./native/secp256k1/src/secp256k1.c"
+    ],
+    "include_dirs": [
+      "/usr/local/include",
+      "./native/secp256k1",
+      "./native/secp256k1/contrib",
+      "./native/secp256k1/include",
+      "./native/secp256k1/src",
+      "<!(node -e \"require('nan')\")"
+    ],
+    "defines": [],
+    "cflags": [
+      "-Wall",
+      "-Wno-maybe-uninitialized",
+      "-Wno-uninitialized",
+      "-Wno-unused-function",
+      "-Wextra"
+    ],
+    "cflags_cc+": [
+      "-std=c++11"
+    ],
+    "conditions": [
+      [
+        "with_gmp=='true'", {
+          "defines": [
+            "HAVE_LIBGMP=1",
+            "USE_NUM_GMP=1",
+            "USE_FIELD_INV_NUM=1",
+            "USE_SCALAR_INV_NUM=1"
+          ],
+          "libraries": [
+            "-lgmpxx",
+            "-lgmp"
+          ]
+        }, {
+          "defines": [
+            "USE_NUM_NONE=1",
+            "USE_FIELD_INV_BUILTIN=1",
+            "USE_SCALAR_INV_BUILTIN=1"
+          ]
+        }
+      ],
+      [
+        "target_arch=='x64' and OS!='win'", {
+          "defines": [
+            "HAVE___INT128=1",
+            "USE_ASM_X86_64=1",
+            "USE_FIELD_5X52=1",
+            "USE_FIELD_5X52_INT128=1",
+            "USE_SCALAR_4X64=1"
+          ]
+        }, {
+          "defines": [
+            "USE_FIELD_10X26=1",
+            "USE_SCALAR_8X32=1"
+          ]
+        }
+      ],
+      [
+        "OS=='mac'", {
+          "libraries": [
+            "-L/usr/local/lib"
+          ],
+          "xcode_settings": {
+            "MACOSX_DEPLOYMENT_TARGET": "10.7",
+            "OTHER_CPLUSPLUSFLAGS": [
+              "-stdlib=libc++"
+            ]
+          }
+        }
+      ]
+    ]
+  }]
+}

native/addon.cpp

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+#include <memory>
+#include <node.h>
+#include <nan.h>
+#include <secp256k1.h>
+
+#define EXPECT_ARGS(N) if (info.Length() != N) return Nan::ThrowTypeError("Wrong number of arguments")
+#define THROW_PRIVATE_KEY Nan::ThrowTypeError("Expected Private Key")
+#define THROW_PUBLIC_KEY Nan::ThrowTypeError("Expected Public Key")
+#define THROW_BAD_TWEAK Nan::ThrowTypeError("Expected Tweak")
+#define RETURNV(X) info.GetReturnValue().Set(X)
+
+extern secp256k1_context* secp256k1ctx;
+
+namespace {
+	v8::Local<v8::Object> asBuffer (const unsigned char* data, const size_t length) {
+		return Nan::CopyBuffer(reinterpret_cast<const char*>(data), static_cast<uint32_t>(length)).ToLocalChecked();
+	}
+
+	template <typename T>
+	const unsigned char* asDataPointer (const T& x) {
+		return reinterpret_cast<const unsigned char*>(node::Buffer::Data(x));
+	}
+
+	template <typename T>
+	bool isUInt256 (const T& x) {
+		return node::Buffer::HasInstance(x) && node::Buffer::Length(x) == 32;
+	}
+
+	template <typename T>
+	bool isPrivateKey (const T& x) {
+		if (!isUInt256<T>(x)) return false;
+		return secp256k1_ec_seckey_verify(secp256k1ctx, asDataPointer(x)) == 1;
+	}
+
+	template <typename T>
+	bool isPublicKey (const T& x, secp256k1_pubkey& pubkey) {
+		if (!node::Buffer::HasInstance(x)) return false;
+		return secp256k1_ec_pubkey_parse(secp256k1ctx, &pubkey, asDataPointer(x), node::Buffer::Length(x)) != 0;
+	}
+}
+
+NAN_METHOD(privateKeyTweakAdd) {
+	Nan::HandleScope scope;
+	EXPECT_ARGS(2);
+
+	const auto priv = info[0].As<v8::Object>();
+	const auto tweak = info[1].As<v8::Object>();
+	if (!isPrivateKey(priv)) return THROW_PRIVATE_KEY;
+	if (!isUInt256(tweak)) return THROW_BAD_TWEAK;
+
+	unsigned char output[32];
+	memcpy(output, asDataPointer(priv), 32);
+	if (secp256k1_ec_privkey_tweak_add(secp256k1ctx, output, asDataPointer(tweak)) == 0) return RETURNV(Nan::Null());
+
+	return RETURNV(asBuffer(output, 32));
+}
+
+NAN_METHOD(privateKeyValidate) {
+	Nan::HandleScope scope;
+	EXPECT_ARGS(1);
+
+	const auto priv = info[0].As<v8::Object>();
+	return RETURNV(isPrivateKey(priv));
+}
+
+NAN_METHOD(publicKeyDerive) {
+	Nan::HandleScope scope;
+	EXPECT_ARGS(2);
+
+	const auto priv = info[0].As<v8::Object>();
+	const auto flags = info[1]->BooleanValue() ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED;
+	if (!isPrivateKey(priv)) return THROW_PRIVATE_KEY;
+
+	secp256k1_pubkey public_key;
+	if (secp256k1_ec_pubkey_create(secp256k1ctx, &public_key, asDataPointer(priv)) == 0) return RETURNV(Nan::Null());
+
+	unsigned char output[65];
+	size_t output_length = 65;
+	secp256k1_ec_pubkey_serialize(secp256k1ctx, output, &output_length, &public_key, flags);
+
+	return RETURNV(asBuffer(output, output_length));
+}
+
+NAN_METHOD(publicKeyReform) {
+	Nan::HandleScope scope;
+	EXPECT_ARGS(2);
+
+	const auto pub = info[0].As<v8::Object>();
+	const auto flags = info[1]->BooleanValue() ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED;
+
+	secp256k1_pubkey public_key;
+	if (!isPublicKey(pub, public_key)) return THROW_PUBLIC_KEY;
+
+	unsigned char output[65];
+	size_t output_length = 65;
+	secp256k1_ec_pubkey_serialize(secp256k1ctx, output, &output_length, &public_key, flags);
+
+	return RETURNV(asBuffer(output, output_length));
+}
+
+NAN_METHOD(publicKeyTweakAdd) {
+	Nan::HandleScope scope;
+	EXPECT_ARGS(3);
+
+	const auto pub = info[0].As<v8::Object>();
+	const auto tweak = info[1].As<v8::Object>();
+	const auto flags = info[2]->BooleanValue() ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED;
+
+	secp256k1_pubkey public_key;
+	if (!isPublicKey(pub, public_key)) return THROW_PUBLIC_KEY;
+	if (!isUInt256(tweak)) return THROW_BAD_TWEAK;
+
+	if (secp256k1_ec_pubkey_tweak_add(secp256k1ctx, &public_key, asDataPointer(tweak)) == 0) return RETURNV(Nan::Null());
+
+	unsigned char output[65];
+	size_t output_length = 65;
+	secp256k1_ec_pubkey_serialize(secp256k1ctx, output, &output_length, &public_key, flags);
+
+	return RETURNV(asBuffer(output, output_length));
+}
+
+NAN_METHOD(publicKeyValidate) {
+	Nan::HandleScope scope;
+	EXPECT_ARGS(1);
+
+	const auto pub = info[0].As<v8::Object>();
+
+	secp256k1_pubkey public_key;
+	return RETURNV(isPublicKey(pub, public_key));
+}

native/index.js

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+'use strict'
+module.exports = require('bindings')('secp256k1')

package.json

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+{
+  "name": "tiny-secp256k1",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "gypfile": true,
+  "engines": {
+    "node": ">=4.0.0"
+  },
+  "scripts": {
+    "build": "node-gyp rebuild"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/dcousens/secp256k1-tiny.git"
+  },
+  "author": "",
+  "license": "ISC",
+  "gypfile": true,
+  "bugs": {
+    "url": "https://github.com/dcousens/secp256k1-tiny/issues"
+  },
+  "homepage": "https://github.com/dcousens/secp256k1-tiny#readme",
+  "dependencies": {
+    "bindings": "^1.3.0",
+    "nan": "^2.7.0"
+  }
+}

scripts/checklib

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+#!/usr/bin/env bash
+function check () {
+  local regex="lib$1.+(so|dylib)"
+
+  # Add /sbin to path as ldconfig is located there on some systems - e.g. Debian
+  # (and it still can be used by unprivileged users):
+  PATH="$PATH:/sbin"
+  export PATH
+
+  # Try just checking common library locations
+  for dir in /lib /usr/lib /usr/local/lib /opt/local/lib /usr/lib/x86_64-linux-gnu /usr/lib/i386-linux-gnu; do
+    if test -d $dir; then
+		# shellcheck disable=SC2010
+		ls $dir | grep -E "$regex" && return 0
+	fi
+  done
+
+  return 1
+}
+
+check "$1" > /dev/null
+if test "$?" -eq 0; then
+  echo true
+else
+  echo false
+fi