Date: Thu, 04 May 2000 22:22:23 +0200 From: Mark Murray <mark@grondar.za> To: "Andrew J. Korty" <ajk@iu.edu> Cc: security@FreeBSD.ORG Subject: Re: Cryptographic dump(8) Message-ID: <200005042022.WAA07642@grimreaper.grondar.za> In-Reply-To: <Pine.BSF.4.21.0005041323480.26511-100000@verbal.uits.iupui.edu> ; from "Andrew J. Korty" <ajk@iu.edu> "Thu, 04 May 2000 13:31:15 EST." References: <Pine.BSF.4.21.0005041323480.26511-100000@verbal.uits.iupui.edu>
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> I'm starting to second guess this decision, since an attacker could
> get inode numbers from the cleartext headers and perform known-text
> attacks by guessing which binaries have those inode numbers.
You are thinking about this in very much the right way! :-)
> If I need to put the random string at the beginning of the header,
> then we're throwing the old file format out the window anyway, so
> I might as well encrypt everything.
...Unless you could flag it in some creative way "the rest of this is
encrypted; sod off"?
> The reason for the separation is so that one corrupted block does
> not render the entire tape useless.
Could you break it in a way that would not compromise the crypto;
that is break the stream at ${count} ${units}, rather than at
"logical" boundaries, in such a way that the stream can be recovered
at some point at the expense of maybe losing a ${block} if it
contains a corruption?
M
--
Mark Murray
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