Technical feasibility of decrypting https by replacing the computer's PRNG Intel has an on-chip RdRand function which supposedly bypasses the normally used entropy pool for /dev/urandom and directly injects output. Now rumors are going on that Intel works together with the NSA... and knowing that PRNGs are important for cryptography is enough to get this news spreading.

I personally don't believe this is true, so this is entirely hypothetical: Let's assume that indeed RdRand does what news says it does and that it indeed outputs randomness into a place where applications and libraries would look for cryptographically secure randomness.


How feasible is it that the chip's manufacturer can predict the output of this PRNG when it passed tests from the people applying the use of this RdRand instruction in kernels?
If the chip's manufacturer can predict the output of the PRNG to some extent, how feasible is it that they can decrypt any https traffic between two systems using their chips? (Or anything else requiring randomness, https is only an example.)


My reason for asking: http://cryptome.org/2013/07/intel-bed-nsa.htm
As said, I don't believe everything written here, but I find it very interesting to discuss the possibility technically.
1 - How feasible is it that the chip's manufacturer can predict the output of this PRNG when it passed tests from the people applying the use of this RdRand instruction in kernels?


A strong stream cipher's output is random and unpredictable to anyone not knowing the key. See where this is heading? Just because something looks random doesn't mean it's random.


  2 - If the chip's manufacturer can predict the output of the PRNG to some extent, how feasible is it that they can decrypt any https traffic between two systems using their chips? (Or anything else requiring randomness, https is only an example.)


If you can predict the PRNG you can basically predict the secrets used for key exchange, and from that deduce the shared secret. Then you can simply decrypt the communication.