RE: Hard Drive data security

From: Atom 'Smasher' (atom_at_suspicious.org)
Date: 10/07/04

  • Next message: Atom 'Smasher': "Re: Hard Drive data security" 
    Date: Thu, 7 Oct 2004 00:04:49 -0400 (EDT)
To: "Security Basics[List]" <security-basics@securityfocus.com>

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    On Tue, 5 Oct 2004, Paris E. Stone wrote:

    > I was informed that /dev/null just wrote zeros to the drive and that a
    > better way was multiple passes using random:
    >
    > dd if=/dev/urandom of=/dev/had
    >
    > or maybe /dev/random
    >
    > Not positive, so many *nixes with their own ways of doing things.
    >
    > But basically /dev/urandom writes ones and zeros in random fashion.
    ==========================

    typically, on systems that have them, /dev/random is "true" random and
    /dev/urandom is a CSPRNG.

    http://en.wikipedia.org/wiki/CSPRNG

    what makes /dev/urandom better than /dev/random for wiping a disk is that
    it can generate output a *lot* faster.

    if a few passes over a disk from /dev/urandom isn't good enough, use a
    sledgehammer (and safety glasses).

             ...atom

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