[Bug 706011] Re: gpg --key-gen doesn't have enough entropy and rng-tools install/start fails

[Steve Beattie]

aporter,

The likely reason 'ls -R /' doesn't generate enough entropy for you is
that the only thing going to be read from the filesystem is the contents
of all the directories and perhaps some metadata on the files
themselves, which in a minimal filesystem may not generate sufficient
disk activity to capture enough entropy. Furthermore, your system may
have enough RAM that your system may have already cached most of the
directory tree into kernel memory, meaning that little disk activity is
generated by this command.

When I need to generate entropy in one of my remote vms and I don't have
access to an entropy key device, I usually do something like

  find /var/ /usr /lib /srv -type f -print0 | xargs -0 cat > /dev/null

possibly within a loop (but the contents of my disk will be larger than
the memory allocated to the VM, ensuring that performing the find
command multiple times will continue to generate disk activity; the VM
won't be able to cache all of the disk's contents in memory).

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https://bugs.launchpad.net/bugs/706011

Title:
  gpg --key-gen doesn't have enough entropy and rng-tools install/start
  fails

Status in “gnupg” package in Ubuntu:
  Invalid

Bug description:
  Binary package hint: gnupg

  Description:	Ubuntu 10.04.1 LTS
  Release:	10.04

  
  If you install gpg and then type: gpg --gen-key, it 'freezes up' during the entropy gathering phase.

  ....
  We need to generate a lot of random bytes. It is a good idea to perform
  some other action (type on the keyboard, move the mouse, utilize the
  disks) during the prime generation; this gives the random number
  generator a better chance to gain enough entropy.

  Not enough random bytes available.  Please do some other work to give
  the OS a chance to collect more entropy! (Need 278 more bytes)
  ....
  (freeze here)

  I found some reference on the interwebs suggesting to install rng-
  tools so that the rngd daemon can gather more entropy for the system
  because by default cat /proc/sys/kernel/random/entropy_avail has a
  very very low number.

  Thus, installation of rng-tools, fails to start the rngd daemon...

  Setting up rng-tools (2-unofficial-mt.12-1ubuntu3) ...
  Trying to create /dev/hwrng device inode...
  Starting Hardware RNG entropy gatherer daemon: (failed).
  invoke-rc.d: initscript rng-tools, action "start" failed.

  It is then required to do this: echo "HRNGDEVICE=/dev/urandom" >> /etc/default/rng-tools
  and then start rngd: /etc/init.d/rng-tools start

  After this process is done, gpg --gen-key is immediate...

  
  We need to generate a lot of random bytes. It is a good idea to perform
  some other action (type on the keyboard, move the mouse, utilize the
  disks) during the prime generation; this gives the random number
  generator a better chance to gain enough entropy.
  .........+++++
  ...+++++
  We need to generate a lot of random bytes. It is a good idea to perform
  some other action (type on the keyboard, move the mouse, utilize the
  disks) during the prime generation; this gives the random number
  generator a better chance to gain enough entropy.
  +++++
  .+++++

  And cat /proc/sys/kernel/random/entropy_avail has a much higher
  number.

  All in all, I think this process should be simplified by maybe making
  gpg depend on rng-tools. The whole reason why I need to generate a gpg
  key is because I want to sign the .deb debians that I'm creating for
  my repository.

  Thanks for your time.

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