remove buffer usage everywhere.

event.ts

@@ -1,8 +1,8 @@
-import {Buffer} from 'buffer'
-// @ts-ignore
 import * as secp256k1 from '@noble/secp256k1'
 import {sha256} from '@noble/hashes/sha256'
 
+import {utf8Encoder} from './utils'
+
 export type Event = {
   id?: string
   sig?: string
@@ -35,8 +35,8 @@ export function serializeEvent(evt: Event): string {
 }
 
 export function getEventHash(event: Event): string {
-  let eventHash = sha256(Buffer.from(serializeEvent(event)))
-  return Buffer.from(eventHash).toString('hex')
+  let eventHash = sha256(utf8Encoder.encode(serializeEvent(event)))
+  return secp256k1.utils.bytesToHex(eventHash)
 }
 
 export function validateEvent(event: Event): boolean {
@@ -63,7 +63,7 @@ export function verifySignature(
 }
 
 export async function signEvent(event: Event, key: string): Promise<string> {
-  return Buffer.from(
+  return secp256k1.utils.bytesToHex(
     await secp256k1.schnorr.sign(event.id || getEventHash(event), key)
-  ).toString('hex')
+  )
 }

keys.ts

@@ -1,10 +1,9 @@
 import * as secp256k1 from '@noble/secp256k1'
-import {Buffer} from 'buffer'
 
 export function generatePrivateKey(): string {
-  return Buffer.from(secp256k1.utils.randomPrivateKey()).toString('hex')
+  return secp256k1.utils.bytesToHex(secp256k1.utils.randomPrivateKey())
 }
 
 export function getPublicKey(privateKey: string): string {
-  return Buffer.from(secp256k1.schnorr.getPublicKey(privateKey)).toString('hex')
+  return secp256k1.utils.bytesToHex(secp256k1.schnorr.getPublicKey(privateKey))
 }

nip06.ts

@@ -1,3 +1,4 @@
+import * as secp256k1 from '@noble/secp256k1'
 import {wordlist} from '@scure/bip39/wordlists/english.js'
 import {
   generateMnemonic,
@@ -7,14 +8,14 @@ import {
 import {HDKey} from '@scure/bip32'
 
 export function privateKeyFromSeed(seed: string): string {
-  let root = HDKey.fromMasterSeed(Buffer.from(seed, 'hex'))
+  let root = HDKey.fromMasterSeed(secp256k1.utils.hexToBytes(seed))
   let privateKey = root.derive(`m/44'/1237'/0'/0/0`).privateKey
   if (!privateKey) throw new Error('could not derive private key')
-  return Buffer.from(privateKey).toString('hex')
+  return secp256k1.utils.bytesToHex(privateKey)
 }
 
 export function seedFromWords(mnemonic: string): string {
-  return Buffer.from(mnemonicToSeedSync(mnemonic)).toString('hex')
+  return secp256k1.utils.bytesToHex(mnemonicToSeedSync(mnemonic))
 }
 
 export function generateSeedWords(): string {