add privateKeyToPublicKey function to accounts (#6466)

Author: Alex

packages/web3-eth-accounts/CHANGELOG.md

@@ -139,6 +139,10 @@ Documentation:
 
 ## [Unreleased]
 
+### Added
+
+-   Added public function `privateKeyToPublicKey`
+
 ### Fixed
 
--   Fixed `recover` function, `v` will be normalized to value 0,1 (#6344) 
+-   Fixed `recover` function, `v` will be normalized to value 0,1 (#6344) 

packages/web3-eth-accounts/src/account.ts

@@ -386,6 +386,25 @@ export const privateKeyToAddress = (privateKey: Bytes): string => {
 	return toChecksumAddress(`0x${address}`);
 };
 
+/**
+ * Get the public key from a private key
+ *
+ * @param privateKey - String or Uint8Array of 32 bytes
+ * @param isCompressed - if true, will generate a 33 byte compressed public key instead of a 65 byte public key 
+ * @returns The public key
+ * @example
+ * ```ts
+ * privateKeyToAddress("0x1e046a882bb38236b646c9f135cf90ad90a140810f439875f2a6dd8e50fa261f", true)
+ * > "0x42beb65f179720abaa3ec9a70a539629cbbc5ec65bb57e7fc78977796837e537662dd17042e6449dc843c281067a4d6d8d1a1775a13c41901670d5de7ee6503a" // uncompressed public key
+ * ```
+ */
+ export const privateKeyToPublicKey = (privateKey: Bytes, isCompressed: boolean): string => {
+	const privateKeyUint8Array = parseAndValidatePrivateKey(privateKey);
+
+	// Get public key from private key in compressed format
+	return `0x${bytesToHex(secp256k1.getPublicKey(privateKeyUint8Array, isCompressed)).slice(4)}`; // 0x and removing compression byte
+};
+
 /**
  * encrypt a private key with a password, returns a V3 JSON Keystore
  *

packages/web3-eth-accounts/test/fixtures/account.ts

@@ -24,7 +24,7 @@ import {
 	IVLengthError,
 	PBKDF2IterationsError,
 } from 'web3-errors';
-import { CipherOptions, KeyStore } from 'web3-types';
+import { CipherOptions, KeyStore, Bytes } from 'web3-types';
 import { hexToBytes } from 'web3-utils';
 import { AccessListEIP2930TxData, FeeMarketEIP1559TxData, TxData } from '../../src/tx/types';
 import { sign, signTransaction, encrypt } from '../../src/account';
@@ -221,6 +221,31 @@ export const invalidPrivateKeytoAccountData: [
 	[new Uint8Array([]), new PrivateKeyLengthError()],
 ];
 
+export const validPrivateKeyToPublicKeyData: [
+	Bytes, boolean, string // private key, isCompressed, public key
+][] = [
+	[
+		"0x1e046a882bb38236b646c9f135cf90ad90a140810f439875f2a6dd8e50fa261f",  // test string to uncompressed publickey
+		false,
+		"0x42beb65f179720abaa3ec9a70a539629cbbc5ec65bb57e7fc78977796837e537662dd17042e6449dc843c281067a4d6d8d1a1775a13c41901670d5de7ee6503a",
+	],
+	[
+		"0x1e046a882bb38236b646c9f135cf90ad90a140810f439875f2a6dd8e50fa261f",  // test string to compressed publickey
+		true,
+		"0x42beb65f179720abaa3ec9a70a539629cbbc5ec65bb57e7fc78977796837e537",
+	],
+	[
+		hexToBytes("0xd933beabed94a9f23917576596b2bc64ffeacfe5ded09a99c0feee8369bd295d"), // test uint8array to uncompressed publickey
+		false,
+		"0x7891db4ed2d26584b0fa87329c40b398c940c08e7dbeb8e3dad83f34dba284c933fb14b1edd8893fa89af3823fd827ee59044033ca068803030afc294de5f390",
+	],
+	[
+		hexToBytes("0xd933beabed94a9f23917576596b2bc64ffeacfe5ded09a99c0feee8369bd295d"), // test uint8array to compressed publickey
+		true,
+		"0x7891db4ed2d26584b0fa87329c40b398c940c08e7dbeb8e3dad83f34dba284c9",
+	],
+];
+
 export const validEncryptData: [[any, string | Uint8Array, CipherOptions], KeyStore][] = [
 	[
 		[

packages/web3-eth-accounts/test/unit/account.test.ts

@@ -28,6 +28,7 @@ import {
 	recoverTransaction,
 	sign,
 	signTransaction,
+	privateKeyToPublicKey
 } from '../../src/account';
 import {
 	invalidDecryptData,
@@ -42,6 +43,7 @@ import {
 	validHashMessageData,
 	validPrivateKeytoAccountData,
 	validPrivateKeyToAddressData,
+	validPrivateKeyToPublicKeyData,
 	validRecover,
 } from '../fixtures/account';
 import { TransactionFactory } from '../../src/tx/transactionFactory';
@@ -91,6 +93,13 @@ describe('accounts', () => {
 			});
 		});
 	});
+	describe('privateKeyToPublicKey', () => {
+		describe('valid cases', () => {
+			it.each(validPrivateKeyToPublicKeyData)('%s', (privateKey, isCompressed, output) => {
+				expect(privateKeyToPublicKey(privateKey, isCompressed)).toEqual(output);
+			});
+			})
+	})
 
 	describe('Signing and Recovery of Transaction', () => {
 		it.each(transactionsTestData)('sign transaction', async txData => {