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FredrickB
Reader I

Re: PKI and Quantum Computing

Hi, fresh here so apologies for any mistakes by me!  A question about RSA, strenghth  and quantum computing (qubits), I have heard  in conferences and lectures over the past years quite different stories on how many qubits it takes to actually break RSA cryptography, a range from "a few" to "several hundreds", I guess this also depends on the quality of the qubits and their entanglement, but does anyone have a good estimate?

rslade
Influencer II

Re: PKI and Quantum Computing

> FredrickB (Viewer) posted a new reply in Tech Talk on 02-18-2021 09:50 AM in the

> Hi, fresh here so apologies for any mistakes by me!  A question about RSA,
> strenghth  and quantum computing (qubits), I have heard  in conferences and
> lectures over the past years quite different stories on how many qubits it takes
> to actually break RSA cryptography, a range from "a few" to "several hundreds",
> I guess this also depends on the quality of the qubits and their entanglement,
> but does anyone have a good estimate?

Using the Shor algorithm you need twice as many qubits as the length of the key.
So, to break a 4,000 bit key, you need a machine with 8,000 qubits.

Since, except for D-Wave, we are only barely into double digits on most quantum
computers, we have some ways to go. (D-Wave doesn't count, since it is best
described as a quantum co-processor, rather than a full-fledged quantum computer.
Specifically, it cannot run the Shor algorithm.)

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