3 ms·
According to http://www.outflux.net/blog/archives/2009/10/22/tpm-as-rng/#comment-793 http://www.outflux.net/blog/archives/2009/10/22/tpm-as-rng/#..., TPM may ev
by JoachimSchipper 15y ago
According to http://www.outflux.net/blog/archives/2009/10/22/tpm-as-rng/#comment-793 http://www.outflux.net/blog/archives/2009/10/22/tpm-as-rng/#..., TPM may even be using PRNGs. So you're right that the quality of output need not be better than what a modern OS already provides. (I am not aware of any case where a properly-used /dev/random failed to produce sufficient entropy. Note that doing something sensible at boot is part of "properly-used" here.)
It is possible to provide true randomness from a chip, but it's probably cheaper not to.
- __alexs 15y agoThe Intel TRNG design used for RdRand in Ivy Bridge has an impressively low transistor count so I don't think die-cost alone is the issue. http://spectrum.ieee.org/semiconductors/processors/behind-intels-new-randomnumber-generator/0 http://spectrum.ieee.org/semiconductors/processors/behind-in... http://en.wikipedia.orghwiki/RdRand http://en.wikipedia.orghwiki/RdRand I suspect they just didn't consider RNG quality as a big factor in the usefulness of the design. TPM pre-dates the recent advances in on-die TRNG design. Plus the chip tends to live on a low-speed bus on the system which makes it inherently a bit crappy as a place to keep a high-bandwidth application like an RNG.