Build this with
the passphrase as a PrivSecretBuf.
Optional limitName: stringoptional limit name (['interactive', 'moderate' default, 'sensitive']).
Will throw an error if the passphrase is not an instance of PrivSecretBuf.
Private Optional limitPrivate passphraseEncrypt a secretSeed SeedCipher with this instance.
the secret seed to encrypt.
the encrypted seed as an object.
Will throw an error if the secret seed is not an instance of PrivSecretBuf.
SeedCipher locked by a password hash.