From e3da92d1ee8182aec4370bb1a4e347b462684d2e Mon Sep 17 00:00:00 2001
From: Richard Moore <github@ricmoo.com>
Date: Sun, 22 Jul 2018 20:05:14 -0400
Subject: [PATCH] Lazy load the elliptic curve; also fixed circular
 dependencies internal to the library that cause issues in browserify.

---
 src.ts/utils/secp256k1.ts    | 28 ++++++++++++++--------------
 src.ts/utils/transaction.ts  |  2 +-
 src.ts/wallet/hdnode.ts      |  4 +++-
 src.ts/wallet/signing-key.ts | 11 -----------
 4 files changed, 18 insertions(+), 27 deletions(-)

diff --git a/src.ts/utils/secp256k1.ts b/src.ts/utils/secp256k1.ts
index 8e65b1faa..5c660fd50 100644
--- a/src.ts/utils/secp256k1.ts
+++ b/src.ts/utils/secp256k1.ts
@@ -8,11 +8,20 @@ import { arrayify, hexlify, hexZeroPad, splitSignature } from './bytes';
 import { hashMessage } from './hash';
 import { keccak256 } from './keccak256';
 import { defineReadOnly } from './properties';
+import { ec as EC } from 'elliptic';
 
 import { Arrayish, Signature } from './types';
 
 import * as errors from './errors';
 
+let _curve: EC = null
+function getCurve() {
+    if (!_curve) {
+        _curve = new EC('secp256k1');
+    }
+    return _curve;
+}
+
 
 export class KeyPair {
 
@@ -24,7 +33,7 @@ export class KeyPair {
     readonly publicKeyBytes: Uint8Array;
 
     constructor(privateKey: Arrayish) {
-        let keyPair = curve.keyFromPrivate(arrayify(privateKey));
+        let keyPair = getCurve().keyFromPrivate(arrayify(privateKey));
 
         defineReadOnly(this, 'privateKey', hexlify(keyPair.priv.toArray('be', 32)));
         defineReadOnly(this, 'publicKey', '0x' + keyPair.getPublic(false, 'hex'));
@@ -33,7 +42,7 @@ export class KeyPair {
     }
 
     sign(digest: Arrayish): Signature {
-        let keyPair = curve.keyFromPrivate(arrayify(this.privateKey));
+        let keyPair = getCurve().keyFromPrivate(arrayify(this.privateKey));
         let signature = keyPair.sign(arrayify(digest), {canonical: true});
         return {
             recoveryParam: signature.recoveryParam,
@@ -50,7 +59,7 @@ export function recoverPublicKey(digest: Arrayish, signature: Signature): string
         r: arrayify(signature.r),
         s: arrayify(signature.s)
     };
-    return '0x' + curve.recoverPubKey(arrayify(digest), sig, signature.recoveryParam).encode('hex', false);
+    return '0x' + getCurve().recoverPubKey(arrayify(digest), sig, signature.recoveryParam).encode('hex', false);
 }
 
 export function computePublicKey(key: Arrayish, compressed?: boolean): string {
@@ -66,11 +75,11 @@ export function computePublicKey(key: Arrayish, compressed?: boolean): string {
 
     } else if (bytes.length === 33) {
         if (compressed) { return hexlify(bytes); }
-        return '0x' + curve.keyFromPublic(bytes).getPublic(false, 'hex');
+        return '0x' + getCurve().keyFromPublic(bytes).getPublic(false, 'hex');
 
     } else if (bytes.length === 65) {
         if (!compressed) { return hexlify(bytes); }
-        return '0x' + curve.keyFromPublic(bytes).getPublic(true, 'hex');
+        return '0x' + getCurve().keyFromPublic(bytes).getPublic(true, 'hex');
     }
 
     errors.throwError('invalid public or private key', errors.INVALID_ARGUMENT, { arg: 'key', value: '[REDACTED]' });
@@ -102,12 +111,3 @@ export function verifyMessage(message: Arrayish | string, signature: Signature |
     );
 }
 
-// !!!!!! IMPORTANT !!!!!!!!
-//
-// This import MUST be at the bottom, otehrwise browserify executes several imports
-// BEFORE they are exported, resulting in undefined
-
-import { ec as EC } from 'elliptic';
-const curve = new EC('secp256k1');
-
-export const N = '0x' + curve.n.toString(16);
diff --git a/src.ts/utils/transaction.ts b/src.ts/utils/transaction.ts
index b6aee9374..1ef66d5ec 100644
--- a/src.ts/utils/transaction.ts
+++ b/src.ts/utils/transaction.ts
@@ -3,6 +3,7 @@ import { getAddress } from './address';
 import { bigNumberify, ConstantZero } from './bignumber';
 import { arrayify, hexlify, hexZeroPad, splitSignature, stripZeros, } from './bytes';
 import { keccak256 } from './keccak256';
+import { recoverAddress } from './secp256k1';
 
 import * as RLP from './rlp';
 
@@ -159,4 +160,3 @@ export function parse(rawTransaction: Arrayish): Transaction {
     return tx;
 }
 
-import { recoverAddress } from './secp256k1';
diff --git a/src.ts/wallet/hdnode.ts b/src.ts/wallet/hdnode.ts
index 2e3c26888..011bb5fe7 100644
--- a/src.ts/wallet/hdnode.ts
+++ b/src.ts/wallet/hdnode.ts
@@ -17,9 +17,11 @@ import { toUtf8Bytes, UnicodeNormalizationForm } from '../utils/utf8';
 import { pbkdf2 } from '../utils/pbkdf2';
 import { computeHmac } from '../utils/hmac';
 import { defineReadOnly } from '../utils/properties';
-import { KeyPair, N } from '../utils/secp256k1';
+import { KeyPair } from '../utils/secp256k1';
 import { sha256 } from '../utils/sha2';
 
+const N = bigNumberify("0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141");
+
 import { Arrayish, HDNode as _HDNode ,Wordlist } from '../utils/types';
 
 import * as errors from '../utils/errors';
diff --git a/src.ts/wallet/signing-key.ts b/src.ts/wallet/signing-key.ts
index 9c9f87f7c..521e74cfe 100644
--- a/src.ts/wallet/signing-key.ts
+++ b/src.ts/wallet/signing-key.ts
@@ -67,14 +67,3 @@ export class SigningKey {
         return this.keyPair.sign(digest);
     }
 }
-/*
-export function recoverAddress(digest: Arrayish, signature: Signature): string {
-    return computeAddress(recoverPublicKey(digest, signature));
-}
-
-export function computeAddress(key: string): string {
-    // Strip off the leading "0x04"
-    let publicKey = '0x' + computePublicKey(key).slice(4);
-    return getAddress('0x' + keccak256(publicKey).substring(26));
-}
-*/