On 2016-01-20 20:33:29, Wiebe Cazemier wrote: > ----- Original Message ----- > > From: "Tyler Hicks" <tyhicks@xxxxxxxxxxxxx> > > To: "Wiebe Cazemier" <wiebe@xxxxxxxxxxxx> > > Cc: ecryptfs@xxxxxxxxxxxxxxx > > Sent: Wednesday, 20 January, 2016 3:48:44 AM > > Subject: Re: bcrypt or other key derivation algorithm > > > > > It should be easy enough to borrow code from OpenSSH, which uses > > > bcrypt in their secure new private key file format (ssh-keygen -o; > > > their old format is pretty weak (MD5 once, encrypt with AES 128)). > > > > > > Questions: > > > > > > 1) The v2 wrapped does not have a field to indicate which algorithm is > > > used (like /etc/shadow (crypt API) has). Does this necessitate a > > > v3, which does have said field? > > > > Yes. The v2 wrapped passphrase format was intended to be the most simple > > fix possible for CVE-2014-9687 in order to make backporting to stable > > releases and transparent upgrades easy. > > > > The thought was always that a v3 would be needed to support greater > > algorithm agility. > > Has there already been plans for the layout of v3? Is it as simple as my suggestion? > > The read_v2_wrapped_passphrase_file method could be renamed to read_v2plus_wrapped_passphrase_file and use different offsets for v3. > > > > > > 2) Are there objections to including BSD licensed code from OpenSSH? > > > > That bit of code looks like it is under the 4-clause BSD license. I > > think that'll be a problem since the ecryptfs-utils project is GPLv2. > > > > Can you reuse the crypt(3) interface, passing the "2a" ID for bcrypt? > > The man page for crypt says: > > 2a | Blowfish (not in mainline glibc; added in some Linux distributions)". > > A Debian 5 system I still have says: > > 2a | Blowfish (on some Linux distributions) > > It's not as portable, apparently. > > Also, it's a little inconvenient that it returns an encoded string, not bytes. But I guess that's convertable. That is a bit unfortunate and could cause issues down the line if there were any changes in encoding. > > I'll look a bit more for bcrypt code/libs. > > Is ecryptfs Linux only, BTW? Yes, eCryptfs is Linux only. Tyler
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