How to encrypt with low entropy secrets

words.filippo.io

4 pointsFiloSottile3 comments

There are also password-authenticated key agreement (PAK) protocols, for obtaining strong security from weak passwords. They are useful in certain use cases.

Magic-wormhole uses a version of that. You encrypt files securely with a couple of words.

They have different use cases: with PAKEs you encrypt a connection, not a file. You can’t use PAKEs to encrypt backups. Or, rather, you can but then the two sides just have to store the key, making it not fit for e2ee use cases. It’s password authenticated key exchange, not password derived keys.

(Well, the WhatsApp solution actually uses a PAKE to talk to the HSM, but the HSM is still necessary.)

Exactly!

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