# Gavin Andresen
# 2011-12-14 23:34:29
# https://bitcointalk.org/index.php?topic=54542.msg650590#msg650590

I spent some time today looking again at the state of quantum computing: I'm still not worried. @p{par}

The D-Wave system is not a general-purpose quantum computer; it is pretty specialized for solving certain problems (I'm reasonably certain cracking ECDSA encryption is not one of the problems it would be good at, but I am definitely NOT a quantum crypto expert). @p{par}

Skimming the research, it looks like you'd need a specially-constructed quantum computer with @p{(link}515 qbits and over 100million quantum gates@p{link)}, running more than 16 million quantum operations to crack Bitcoin's 256-bit ECDSA private keys using Shor's algorithm. @p{par}

There's was a good reality-check article in the New York Times just last week: @p{brk}
   @s{(link)} @p{par}


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 @p{brk}
I've said it before:  I'll start to worry when quantum computers can factor 64-bit numbers. @p{brk}