LUKS hdd encryption: Maximum maximum password length?

Question

Is there any maximum lenght of the passphrase in the hardrive encryption option on ubuntu (luks)?

Solution

LUKS is configured via cryptsetup which has a compiled-in limitation of 512 characters for an interactive passphrase. In theory there is no limitation on the length of the passphrase as it is processed through a key derivation function.

$ crypsetup --help
...
Default compiled-in key and passphrase parameters:
        Maximum keyfile size: 8192kB, Maximum interactive passphrase length 512 (characters)
Default PBKDF2 iteration time for LUKS: 1000 (ms)

Default compiled-in device cipher parameters:
        loop-AES: aes, Key 256 bits
        plain: aes-cbc-essiv:sha256, Key: 256 bits, Password hashing: ripemd160
        LUKS1: aes-xts-plain64, Key: 256 bits, LUKS header hashing: sha1, RNG: /dev/urandom