Comment by itake

> there is nothing saying there was secondary encryption on the phone.

A GrapheneOS phone stores its files encrypted. The PIN is not itself the encryption key; it is used, together with a high-entropy secret protected by the Titan M secure element, to derive the material needed to unlock the randomly generated filesystem-encryption keys.

The duress PIN does not overwrite every file. It irreversibly destroys the multiple layers of key material and encryption metadata needed to decrypt the data, making any encrypted remnants effectively unreadable.

A hypothetical, extraordinarily powerful quantum computer could theoretically decrypt the remaining ciphertext by searching for the encryption keys.