Am Mittwoch, 27. Januar 2016, 15:35:41 schrieb Herbert Xu: Hi Herbert, >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. Ok, I have no problems with that. I put the patches onto my web server if people are interested in it [1]. [1] http://www.chronox.de/kdf.html Ciao Stephan -- 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
