[Cryptography] RNG's available in disk devices

[grarpamp]

FYI, recently released disk drives on the market may
include an onboard 32-byte hardware RNG that can
provide bits to the host for its own use upon request
via the usual command channel per TCG Opal Storage
Specifications.

http://www.trustedcomputinggroup.org/files/resource_files/B15F1F8F-1A4B-B294-D03F09D5122B21F6/Opal_SSC_2%2000_rev1%2000_final.pdf