Quantum computer and bitcoin. Here is a burning soap opera which is not about to fade, especially after the last experiment of IBM.
In short
- IBM has just succeeded in breaking a 6 -bit ECC key, the same type of key used to secure bitcoins.
- The Pauli group thinks that it is not impossible that Bitcoin can be broken between 2027 and 2033. Rather 2033 than 2027.
- Should we panic? Not really, but all the same.
Cryptography and bitcoin
Before explaining the results of IBM, let us take the opportunity to recall in simple terms the functioning of Bitcoin. It is not so complicated to get a good idea of the thing.
Bitcoin uses several cryptographic algorithms (math). One of them is a hatching function called SHA-256. It is in particular with it that bitcoin minors work.
The job of a hash function is to transform any amount of data into a “hash”. Under the hood, a hash is just a number. A very large number. Cryptography works with very large numbers.
“Mining bitcoins” means to pass all the data from a block (a few thousand transactions) to the Sha-256 reel. The goal is to find a hash less than a target number (out of trials and errors, thousands of billions of times per second, hence electricity consumption).
The minor who finds first a valid hash can add a blockchain block and receive the award (just over 3 bitcoins currently). The minors create a block every ten minutes approximately.
So much for the “mining” part.
The other large cryptographic side of Bitcoin concerns the construction of transactions. This time these are an “public key” cryptography. It is she who would be at the mercy of a fairly powerful quantum computer (and not Sha-256).
A wallet is not much more than a program generating pairs of keys used to build transactions. Creating a transaction means creating a “utxo”, that is to say a small piece of code that locks a public key to bitcoins (a figure).
The principle is that only the private key can unlock bitcoins.
Alright. And so, concretely, what is the threat?
6 small bits
It is the mathematics that secure bitcoin. In principle, it is impossible, within a reasonable time, to calculate a private key from a public key. Hundreds of millions of billions of years would take the most powerful classic computer in the world to achieve it.
But not if you have a fairly powerful quantum computer. And the fact is that D -Day happens faster than you think since IBM has just restarted the feasibility of such a quantum attack.
The American giant has just succeed in breaking a 6 -bit ECC key Using Shor algorithm with its IBM_TORINO quantum computer of 133 physical qubits. IBM had already managed to break a 5 -bit key using the same processor in July.
Should we worry? Yes and no. What is worrying (for bitcoin) is that it works. What is less so is the size of the key.
A 6 -bit key is insignificant on the cryptographic level. This means that the universe of solutions is 64 (2⁶). An ordinary PC would overcome such a key in a few microseconds.
This experience is therefore proof of concept rather than a threat to Bitcoin and its 256 -bit keys which are 2 longer. The abstract to be filled is always astronomical. Millions of physical qubits would be needed and probably new progress in the correction of quantum errors.
We are not there yet. For example, the largest IBM processor, Condor, has 1,121 physical qubits. The IBM roadmap predicts only 200 logical qubits by 2029. However, it would take more than 2,330 logical ques to hope to break a Bitcoin key in less than a month.
But beware … IBM thinks, however, being able to get there from 2033:
Is this the end of Bitcoin?
Point at all. The quantum threat will be potentially real on a horizon of 3 to 10 years. The Pauli group thinks that it is not impossible that Bitcoin can be broken between 2027 and 2033. Rather 2033 than 2027.
It is therefore necessary to act as soon as possible to test hypotheses, rotate the keys, create post-quantic roadmaps and make sure that bitcoin has nothing to fear on D-Day.
The problem being that we do not yet have a perfectly ideal solution. Post-quantic cryptography algorithms (for example, Kyber or Dilithium algorithms) would result in a net reduction in the number of block transactions (larger signatures and keys).
Our article on the question of compromises: Bitcoin, the quantum threat is getting closer.
In addition, the Bitcoin protocol is not so easy to change (which is a good thing). We currently have the demonstration with the controversy OP_return… Wallets must be upgraded to support post-quantic cryptography. Wallet hardware will also need a new firmware.
Above all, each bitcoiner will have to move their bitcoins to post-quantic addresses. This will not happen overnight.
Let us finish by stressing that your bitcoins will be vulnerable to a quantum attack if and only if you reuse your Bitcoin addresses. You should never do it. Generate a new address with each transaction!
In all, around 33 % of BTCs are currently vulnerable. Or approximately 6.36 million bitcoins. Of this large total, 4.49 million BTC are vulnerable due to the reuse of addresses. The rest are because of very old types of addresses (mainly bitcoins of Satoshi Nakamoto).
Do not miss our article on the subject: Check if your bitcoins are threatened by the quantum computer.
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