Merge pull request #27 from ChainSafe/mpetrunic/secretkey-utility-met…

…hods

Utility methods for private key

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@chainsafe/bls-js",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "description": "Implementation of bls signature verification for ethereum 2.0",
   "main": "lib/index.js",
   "types": "lib/index.d.ts",

src/privateKey.ts

@@ -1,11 +1,11 @@
 import {BIG} from "@chainsafe/amcl/ctx";
-import {SECRET_KEY_LENGTH} from "./constants";
+import {FP_POINT_LENGTH, SECRET_KEY_LENGTH} from "./constants";
 import assert from "assert";
 import ctx from "./ctx";
 import {padLeft} from "./helpers/utils";
 import {G2point} from "./helpers/g2point";
 import * as random from "secure-random";
-import {BLSDomain, bytes32} from "./types";
+import {BLSDomain, BLSSecretKey, bytes32} from "./types";
 
 export class PrivateKey {
 
@@ -27,6 +27,16 @@ export class PrivateKey {
     return G2point.hashToG2(message, domain).mul(this.value);
   }
 
+  public toBytes(): BLSSecretKey {
+    const buffer = Buffer.alloc(FP_POINT_LENGTH, 0);
+    this.value.tobytearray(buffer, 0);
+    return buffer.slice(FP_POINT_LENGTH - SECRET_KEY_LENGTH);
+  }
+
+  public toHexString(): string {
+    return `0x${this.toBytes().toString('hex')}`;
+  }
+
   public static fromBytes(bytes: Uint8Array): PrivateKey {
     assert(bytes.length === SECRET_KEY_LENGTH, 'Private key should have 32 bytes');
     const value = Buffer.from(bytes);
@@ -48,12 +58,7 @@ export class PrivateKey {
   }
 
   public static random(): PrivateKey {
-    return new PrivateKey(
-      ctx.BIG.frombytearray(
-        padLeft(random.randomBuffer(SECRET_KEY_LENGTH), 48),
-        0
-      )
-    )
+    return PrivateKey.fromBytes(random.randomBuffer(SECRET_KEY_LENGTH));
   }
 
 }

tests/unit/privateKey.test.ts

@@ -0,0 +1,22 @@
+import {PrivateKey} from "../../src/privateKey";
+import {expect} from "chai";
+import {SECRET_KEY_LENGTH} from "../../src/constants";
+
+describe('privateKey', function() {
+
+    it('should generate random private key', function () {
+        const privateKey1 = PrivateKey.random();
+        const privateKey2 = PrivateKey.random();
+        expect(privateKey1).to.not.be.equal(privateKey2);
+    });
+
+    it('should export private key to hex string', function () {
+        const privateKey = '0x9a88071ff0634f6515c7699c97d069dc4b2fa28455f6b457e92d1c1302f0c6bb';
+        expect(PrivateKey.fromHexString(privateKey).toHexString()).to.be.equal(privateKey);
+    });
+
+    it('should export private key to bytes', function () {
+        expect(PrivateKey.random().toBytes().length).to.be.equal(SECRET_KEY_LENGTH);
+    });
+
+});