71–80 of 146 posts
One day you can start calculating private keys based on public keys. This is the biggest crypto puzzle: find private key of Sathoshi Bitcoin wallet with 1 mln bitcoins. Over $50 Bln prize for one crypto puzzle. This would be AlphaGo moment of quantum computing if you could make that one attack successful even while paying huge price (e.g. years of quantum datacenter work).
Earlier quoted context omitted.
> Till we've crypto that's quantum, and daunt 'em. Luckily there are asymmetric algorithms which are are secure against quantum computers, so we don't have to resort to quantum-key-exchanges.
"Secure against quantum" doesn't really mean much because too little is known to make that claim confidently. AFAIK the term generally refers to algorithms that don't rely on factoring being hard, but instead make some different hardness assumptions that we currently don't have classical or quantum algorithms for.
One day you can start calculating private keys based on public keys. This is the biggest crypto puzzle: find private key of Sathoshi Bitcoin wallet with 1 mln bitcoins. Over $50 Bln prize for one crypto puzzle. This would be AlphaGo moment of quantum computing if you could make that one attack successful even while paying huge price (e.g. years of quantum datacenter work).
Cashing out and actually getting $50B may be as much of a challenge as finding the private key
One day you can start calculating private keys based on public keys. This is the biggest crypto puzzle: find private key of Sathoshi Bitcoin wallet with 1 mln bitcoins. Over $50 Bln prize for one crypto puzzle. This would be AlphaGo moment of quantum computing if you could make that one attack successful even while paying huge price (e.g. years of quantum datacenter work).
Approximately one minute after you start this process, someone will figure out that either (1) bitcoins no longer securely belong to anyone or (2) Satoshi thinks selling off all his bitcoin is a good idea.
Approximately two minutes after you start this process, the price of bitcoin will plummet.
Sorry, you will not be taking home $50B today.
that means the past is compromised, with some amount of implementation afterwards. i've always wondered just how much the future is compromised.
i've always thought about encryption this way:
P = some degree of computational power
A = some small unit of P, like a laptop
B = the largest unit of P practically
possible under the same laws of physics as A
(data encrypted by A cannot be "cracked" by B in a reasonable amount of time)
edited for format, then again for clarity
This paper basically explores a hypothetical scenario where scaling quantum memory ends up being cheaper than scaling computational qubits. The title (or abstract) unfortunately does not mention the quantum memory requirements at n=2048 explicitly. For factoring 2048 RSA integers, the technique proposed in the paper would require ~430 million memory qubits (see the table at top of page 16).
How expensive is quantum memory relative to quantum compute, over the long term? Expectations about the answer to this question strongly affect whether or not you find this paper relevant. And the answer depends on the pieces you build your quantum computer out of, e.g. hypothetical photonic architectures have a bigger ratio than hypothetical superconducting qubit architectures.
It is currently very much an open question whether or not quantum computers will have a memory hierarchy.
One day you can start calculating private keys based on public keys. This is the biggest crypto puzzle: find private key of Sathoshi Bitcoin wallet with 1 mln bitcoins. Over $50 Bln prize for one crypto puzzle. This would be AlphaGo moment of quantum computing if you could make that one attack successful even while paying huge price (e.g. years of quantum datacenter work).
Cashing out and actually getting $50B may be as much of a challenge as finding the private key
Earlier quoted context omitted.
> Are we ready for that kind of upheaval? Quite sure cryptographers are ahead of the curve, they are a conservative bunch. There's multiple finalists in the NIST post-quantum comp with different quantum-hard mathematical properties. An over-abundance of lattice cryptography being standardised could possibly be a problem in the long term though. Asymmetric public key crypto and signatures being broken is the only real…
Thanks. I don't understand your last paragraph. Can you provide a bit more context? Just a starting point for an Internet search :)
If a particular address has never sent coins then an attacker has to perform a pre-image attack against SHA-256 and RIPEMD-160 which even for quantum computers would be 2^128 operations (generally believed to be intractable) and wouldn't even require breaking ECDSA.
Since most original coins have never been sent anywhere there isn't a way to directly attack their ECDSA keypairs.
There are, however, plenty of addresses holding (a lot of) coins whose public keys are in the blockchain, making them targets for quantum computing attacks. An attacker could solve the discrete logarithm problem for a key and forge a signature in a transaction sending all the coins owned by the matching signature to a new address owned by the attacker and the transaction would be accepted by everyone.
Earlier quoted context omitted.
...would be like bringing mathematics to Mesopotamia. Can you expound on this? What sort of breakthroughs are bottlenecked by developments in quantum computing?
The hope is that quantum computers will give us an exponential speed up on some problems, which could (again, hopefully) allow us to solve some NP hard problems. This can be extremely useful for scientific computing (e.g. protein folding) and engineering, where computers have to solve complex NP-hard optimisation problems. It could also be possible to use the technology developed for the precise control and measureme…
No it won't
Earlier quoted context omitted.
"Secure against quantum" doesn't really mean much because too little is known to make that claim confidently. AFAIK the term generally refers to algorithms that don't rely on factoring being hard, but instead make some different hardness assumptions that we currently don't have classical or quantum algorithms for.
For practically all computationally secure crypto we use "secure" for "no known attacks faster than we'd like". QCs just extend the set of efficient algorithms.