perf(pg): use native crypto.pbkdf2Sync in sasl auth (brianc#2815)

Author: matej21

packages/pg/lib/sasl.js

@@ -37,7 +37,7 @@ function continueSession(session, password, serverData) {
 
  var saltBytes = Buffer.from(sv.salt, 'base64')
 
- var saltedPassword = Hi(password, saltBytes, sv.iteration)
+ var saltedPassword = crypto.pbkdf2Sync(password, saltBytes, sv.iteration, 32, 'sha256')
 
  var clientKey = hmacSha256(saltedPassword, 'Client Key')
  var storedKey = sha256(clientKey)
@@ -191,17 +191,6 @@ function hmacSha256(key, msg) {
  return crypto.createHmac('sha256', key).update(msg).digest()
 }
 
-function Hi(password, saltBytes, iterations) {
- var ui1 = hmacSha256(password, Buffer.concat([saltBytes, Buffer.from([0, 0, 0, 1])]))
- var ui = ui1
- for (var i = 0; i < iterations - 1; i++) {
- ui1 = hmacSha256(password, ui1)
- ui = xorBuffers(ui, ui1)
- }
-
- return ui
-}
-
 module.exports = {
  startSession,
  continueSession,