update secp256k1 library, add nip04.js

nip04.js

@@ -0,0 +1,36 @@
+import * as secp256k1 from '@noble/secp256k1'
+
+export function encrypt(privkey, pubkey, text) {
+  const key = secp256k1.getSharedSecret(privkey, '02' + pubkey)
+  const normalizedKey = getOnlyXFromFullSharedSecret(key)
+
+  let iv = crypto.randomFillSync(new Uint8Array(16))
+  var cipher = crypto.createCipheriv(
+    'aes-256-cbc',
+    Buffer.from(normalizedKey, 'hex'),
+    iv
+  )
+  let encryptedMessage = cipher.update(text, 'utf8', 'base64')
+  encryptedMessage += cipher.final('base64')
+
+  return [encryptedMessage, Buffer.from(iv.buffer).toString('base64')]
+}
+
+export function decrypt(privkey, pubkey, ciphertext, iv) {
+  const key = secp256k1.getSharedSecret(privkey, '02' + pubkey)
+  const normalizedKey = getOnlyXFromFullSharedSecret(key)
+
+  var decipher = crypto.createDecipheriv(
+    'aes-256-cbc',
+    Buffer.from(normalizedKey, 'hex'),
+    Buffer.from(iv, 'base64')
+  )
+  let decryptedMessage = decipher.update(ciphertext, 'base64')
+  decryptedMessage += decipher.final('utf8')
+
+  return decryptedMessage
+}
+
+function getOnlyXFromFullSharedSecret(fullSharedSecretCoordinates) {
+  return fullSharedSecretCoordinates.substr(2, 64)
+}