<table> <tr><th>Tails version<br/>when encryption was created</th><th>Release date</th><th>LUKS version</th><th>Key derivation function</th><th>Strength</th></tr> <tr><td>5.12 or earlier</td><td>19 April 2023</td><td>LUKS1</td><td>PBKDF2</td><td>Weak</td></tr> <tr><td>5.13 or later</td><td>16 May 2023</td><td>LUKS2</td><td>Argon2id</td><td>Strong</td></tr> </table>
We estimated how much electricity it would cost to guess passphrases of different strengths. As we recommend for the Persistent Storage, we evaluated passphrases made of several random words.
<table> <tr><th>Passphrase length</th><th>PBKDF2</th><th>Argon2id</th></tr> <tr><td>3 random words</td><td>$0.1</td><td>$100</td></tr> <tr><td>4 random words</td><td>$1 000</td><td>$1 000 000</td></tr> <tr><td>5 random words</td><td>$10 000 000</td><td>$10 000 000 000</td></tr> <tr><td>6 random words</td><td>$100 000 000 000</td><td>$100 000 000 000 000</td></tr> <tr><td>7 random words</td><td>$1 000 000 000 000 000</td><td>$1 000 000 000 000 000 000</td></tr> </table>
To understand the maths behind password strength, watch [An information theoretic model of privacy and security metrics](https://media.libreplanet.org/u/libreplanet/m/an-information-theoretic-model-of-privacy-and-security-metrics/).Bill Budington from the EFF explains the concept of entropy and its implication on browser fingerprinting and password safety in accessible terms.
