Date: Tue, 10 Feb 2015 16:49:19 -0600 From: Tyler Hicks <tyhicks@...onical.com> To: oss-security@...ts.openwall.com Subject: Re: eCryptfs key wrapping help to crack user password On 2015-02-10 15:07:24, Sylvain Pelissier wrote: > Hi, > > I have noticed that ecryptfs-utils is the default program used by the > Ubuntu distributions for home folder encryption since version 10.04. > In this case, a wrapping key is generated from the user password > using the hash function SHA-512 applied 65536 times. By default, the > wrapping key is hashed with the default fixed salt > (0x0011223344556677) and stored in the a file. > This was already noticed in bug : > https://bugs.launchpad.net/ecryptfs/+bug/906550 > For Ubuntu installations time-memory trade-off (rainbow tables, etc.) > can apply, as well as bulk dictionary attacks to crack user passwords > of Ubuntu installations when the home folder encryption is activated. > I am currently working to correct this weakness. Thanks for reporting this issue, Sylvain. I have confirmed the analysis above and upstream ecryptfs-utils is working to correct the problem. Tyler Download attachment "signature.asc" of type "application/pgp-signature" (820 bytes)
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