Messages in this thread | | | Date | Mon, 09 Feb 2004 15:07:35 +0300 | From | Edward Shishkin <> | Subject | Re: PATCH - ext2fs privacy (i.e. secure deletion) patch |
| |
Hans Reiser wrote: > > Exactly right. > > Hans > > Jamie Lokier wrote: > > >the grugq wrote: > > > > > >>If, on the other hand, we have a threat model of, say, the police, then > >>things are very different. In the UK, there is a law which requires you > >>to turn over your encryption keys when the court demands them. The > >>police have a tactic for extracting keys which involves physical > >>violence and intimidation. These are very effective against encryption. > >> > >> > > > >This is how to implement secure deletion cryptographically: > > > > - Each time a file is created, choose a random number. > > > > - Encrypt the number with your filesystem key and store the > > encrypted version in the inode. > > > > - The number is used for encrypting that file. > > > >Secure deletion is then a matter of securely deleting the inode. > >The file data does not have to be overwritten. > > > >This is secure against many attacks that "secure deletion" by > >overwriting is weak against. This includes electron microscopes > >looking at the data, and UK law. (The police can demand your > >filesystem key, but nobody knows the random number that belonged to a > >new-deleted inode).
Also they will demand this random number since the court can consider it as a part of your secret key. So just delete your secret key without creating meaningless infrastructure ;) Edward.
> > > >There is a chance the electron microscope may recover the number from > >the securely deleted inode. That is the weakness of this system, > >therefore the inode data should be very thoroughly erased or itself > >subject to careful cryptographic hding. > > > >-- Jamie > >- > >To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > >the body of a message to majordomo@vger.kernel.org > >More majordomo info at http://vger.kernel.org/majordomo-info.html > >Please read the FAQ at http://www.tux.org/lkml/ > > > > > > > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |