Date: Tue, 10 Feb 2015 15:07:24 +0100 From: Sylvain Pelissier <sylvain.pelissier@...il.com> To: oss-security@...ts.openwall.com Subject: eCryptfs key wrapping help to crack user password 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. Sylvain Pelissier
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