One could also ask why Microsoft and Google are excited about quantum computing. Do they know something that we don't?
As I have often noted on this blog, quantum computing has been a colossal failure, and has no hope of any commercial applications in the foreseeable future. It is doubtful whether it is even physically possible.
Cryptography professor Matthew Green writes:
If you’re looking for a nice dose of crypto conspiracy theorizing and want to read a paper by some very knowledgeable cryptographers, I have just the paper for you. Titled “A Riddle Wrapped in an Enigma” by Neal Koblitz and Alfred J. Menezes, it tackles one of the great mysteries of the year 2015. Namely: why did the NSA just freak out and throw its Suite B program down the toilet?These guys are leading experts in elliptic curve cryptography, and long-time NSA watchers. So their speculation is probably better than mine.
The popular press has somehow convinced everyone that Snowden proved the NSA has tricked people into using elliptic curves in order to use a pseudorandom number generator that has an NSA trapdoor, thereby allowing the NSA to spy on everyone.
This story is exaggerated. The so-called trapdoor was publicly known without Snowden, and no one had to use it. The basic elliptic curve technology remains sound.
It is curious that the NSA has deprecated the P-256 elliptic curve, as it has no publicly known weaknesses, and is used for all Bitcoin transactions. The Bitcoin network is hugely successful and out of control, and maybe the NSA is trying to cast fear, uncertainty, and doubt (FUD) on it.
My guess is that either the NSA has been suckered by quantum computing hype like Microsoft and Google, or it wants to discourage elliptic curve cryptography because it is too secure.