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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). > >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/ | ||||||||||||
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