In Ubuntu, I uploaded an rng-tools that supports the RNG in TPM devices (my patch is waiting in Debian). This hardware is available on a bunch of systems, including several Thinkpads and the Intel Q35, Q45 and newer main boards.
While most TPM RNGs aren’t really heavy-duty hardware RNGs, they are at least a mild source of randomness. I’ll be using an entropy key eventually, but for now, the TPM can supplement my collected entropy.
/etc/default/rng-tools:
HRNGDEVICE=/dev/null
RNGDOPTIONS=”–hrng=tpm –fill-watermark=90% –feed-interval=1″
After it’s been running a bit:
Feb 8 19:10:51 linux rngd[13143]: stats: bits received from HRNG source: 6180064
Feb 8 19:10:51 linux rngd[13143]: stats: bits sent to kernel pool: 6166144
Feb 8 19:10:51 linux rngd[13143]: stats: entropy added to kernel pool: 4624608
Feb 8 19:10:51 linux rngd[13143]: stats: FIPS 140-2 successes: 309
Feb 8 19:10:51 linux rngd[13143]: stats: FIPS 140-2 failures: 0
Feb 8 19:10:51 linux rngd[13143]: stats: FIPS 140-2(2001-10-10) Monobit: 0
Feb 8 19:10:51 linux rngd[13143]: stats: FIPS 140-2(2001-10-10) Poker: 0
Feb 8 19:10:51 linux rngd[13143]: stats: FIPS 140-2(2001-10-10) Runs: 0
Feb 8 19:10:51 linux rngd[13143]: stats: FIPS 140-2(2001-10-10) Long run: 0
Feb 8 19:10:51 linux rngd[13143]: stats: FIPS 140-2(2001-10-10) Continuous run: 0
Feb 8 19:10:51 linux rngd[13143]: stats: HRNG source speed: (min=5.207; avg=6.145; max=6.200)Kibits/s
Feb 8 19:10:51 linux rngd[13143]: stats: FIPS tests speed: (min=66.925; avg=75.789; max=112.861)Mibits/s
Feb 8 19:10:51 linux rngd[13143]: stats: Lowest ready-buffers level: 0
Feb 8 19:10:51 linux rngd[13143]: stats: Entropy starvations: 308
Feb 8 19:10:51 linux rngd[13143]: stats: Time spent starving for entropy: (min=3150263; avg=3178447.994; max=3750848)us
And now the kernel entropy pool is high:
$ echo $(cat /proc/sys/kernel/random/entropy_avail)/$(cat /proc/sys/kernel/random/poolsize)
3968/4096
© 2010, Kees Cook. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 License.
Very cool stuff. Any idea if there’s going to be kernel support for G45M devices soon? :D
Comment by Chris Jones — February 9, 2010 @ 12:11 am
BTW, at UDS Oneiric, you may recall a bunch of us were having to run tcsd manually rather than via the initscript; I finally tracked down what was blocking it for me. It was that at some point in the process /var/lib/tpm/system.data got owned by root, and the trousers initscript sets tcsd up to run as (system) user tss. Once I corrected the ownership on that, stuff starts correctly and I now have entropy, hooray!
Comment by Steve Beattie — May 24, 2011 @ 2:29 pm