Bip39 Last Word Default amount of iterations Employed in wallets is 2048. Increasing this amount really should make it more secure against brute power assaults, having said that you will have to store this value. To access your wallet with customized PBKDF2 you ought to use this script (or similar) https://bookmarksea.com/story18537478/bip39-first-4-letters-how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39