Encryption can be keyed from a passphrase or a PKI certificate. Testing a trial password or passphrase typically requires one hash operation. It can be a password, a passphrase, or a hexadecimal string. Fi Protected Access encryption (WPA2) is considered secure, provided a strong passphrase is used. Some Telegram clients allow users to encrypt the local message database by setting a passphrase. First the passphrase and salt are hashed together, yielding an MD5 message digest. In effect, a relatively weak password/passphrase in natural language can be used. This can be authenticated either through Google credentials, or a sync passphrase. The output of the last of these rounds is the resulting passphrase hash. Wireless suites such as aircrack-ng can crack a weak passphrase in less than a minute. However, for additional security the private key itself can be locked with a passphrase. The server never sees the user's passphrase. The user passphrase is strengthened with PKCS#5. Every passphrase leads to a valid wallet. A magistrate judge held that producing the passphrase would constitute self-incrimination.