On Wed, Jan 27, 2016 at 08:33:00AM +0100, Stephan Mueller wrote: > > With the current development of EXT4 encryption we currently have the > logic that the files are either open (read/writable) or closed (not > accessible). > > There is a scenario for a third option: a file is writable in a "device- > locked" state, but not readable. The logic that would implement such mechanism > is nicely described in [1] section D.3.3, especially figure 4. To use such a > mechanism, the generated shared secret should definitely go through a KDF to > ensure that the key has the right size for the underlying symmetric cipher. > > This approach would allow locking your device, but yet the system could still > write confidential data (like getting emails, generating logs, etc.) but the > data is not accessible unless you unlock the device. > > So, my idea was to provide a building block for such encryption scenarios > which I would think will come. > > Besides, if crypto network protocols are contemplated to be included into the > kernel (like TLS), I would think that the KDF should be handled by the kernel > crypto API as a central place for such logic. Thus, my patch would provide the > framework by providing the RNG template handling to have that KDF here. While this is all very nice until such a user is ready for submission into the kernel I'd rather not add this. Thanks, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
