From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anand Jain Subject: Re: [PATCH] fscrypt: add a documentation file for filesystem-level encryption Date: Tue, 22 Aug 2017 10:22:13 +0800 Message-ID: <7a34337d-3214-0a8a-5521-7727364cceb4@oracle.com> References: <20170818194730.61575-1-ebiggers3@gmail.com> <9dcef6c6-a758-ea57-0d51-55f33e365931@oracle.com> <20170821230821.GB8847@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-fscrypt@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Jaegeuk Kim , Richard Weinberger , Michael Halcrow , Eric Biggers To: Eric Biggers , "Theodore Y . Ts'o" Return-path: In-Reply-To: <20170821230821.GB8847@gmail.com> Content-Language: en-US Sender: linux-doc-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org >>> +fscrypt is not guaranteed to protect confidentiality or authenticity >>> +if an attacker is able to manipulate the filesystem offline prior to >>> +an authorized user later accessing the filesystem. >> >> How does fscrypt / Android protect against Evil Maid attack. ? > _However_, an "Evil Maid" attacker can probably still do other, perhaps much > more effective attacks --- e.g. :: >. Or they could attack the actual > file contents encryption which is not authenticated. Or they could mess around > with filesystem metadata on the userdata partition, which is neither encrypted > nor authenticated. In specific, the scenario I had in mind was the above threat. > I suppose that dm-integrity could be used to protect against some of those > attacks, but of course it would not protect against hardware key loggers, etc. OK. I think AE is the only good solution for this, File-name encryption at this stage won't solve any kind of Evil Maid attack, (as it was quoted somewhere else in ML). Further, below, is define but not used. ----- #define FS_AES_256_GCM_KEY_SIZE 32 ----- Thanks, Anand