[Bug 1506995] Re: Ubiquity uses /dev/null when setting up encrypted swap

[Phillip Susi]

There is no significant difference in the "performance" of filling the
volume with zeros, and filling it with random data.  The only difference
is the fact ( broadly understood in the crypto/security community ) that
filling with a known pattern, such as zeros, facilitates recovering the
encryption keys.

See https://en.wikipedia.org/wiki/Known-plaintext_attack

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https://bugs.launchpad.net/bugs/1506995

Title:
  Ubiquity uses /dev/null when setting up encrypted swap

Status in ubiquity package in Ubuntu:
  Opinion
Status in user-setup package in Ubuntu:
  Opinion

Bug description:
  In Ubiquity's script/user-setup-encrypted-swap, the crypt partition is
  zeroed. This leaves it more vulnerable to attacks. The attacker knows
  the partition is zeroed and can more easily find the encryption key.

  The included patch solves this issue, but this can also be done in a
  faster way by using openssl.

  Patched lines:

  dd if=/dev/urandom of=$device bs=16M seek=1 2>/dev/null || true

  Alternative approch:

  openssl enc -aes-256-ctr -pass pass:"$(dd if=/dev/urandom bs=128
  count=1 2>/dev/null | base64)" -nosalt < /dev/zero | head -c $size |
  dd of=$target

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