Quantum computers may be able to break Bitcoin sooner than you think
https://www.techradar.com/news/quantum-computers-may-be-able-to-break-bitcoin-sooner-than-you-think
On est encore tranquille pour quelques années.
https://www.techradar.com/news/quantum-computers-may-be-able-to-break-bitcoin-sooner-than-you-think
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Scientists from the University of Sussex in the UK estimate that quantum systems with 13 million qubits would be sufficient to break the cryptographic algorithm (SHA-256) that secures the Bitcoin blockchain within the space of 24 hours.
Although modern quantum computers come nowhere close to this level of performance (the current record is a comparatively measly 127 qubits), the researchers say significant developments over the next ten years or so could yield quantum machines with sufficient horsepower.
Although modern quantum computers come nowhere close to this level of performance (the current record is a comparatively measly 127 qubits), the researchers say significant developments over the next ten years or so could yield quantum machines with sufficient horsepower.
On est encore tranquille pour quelques années.
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Via NewScientist
Ils reprennent malheureusement l'information sans la vérifier, donc il vaut mieux se référer directement à l'étude. L'attaque contre SHA256 serait une attaque de minage, consistant a battre tout le reste du réseau de mineurs, elle semble donc très difficilement réalisable et surtout, elle ne pourrait marcher qu'une seule fois car elle serait tout de suite repérée. Elle serait en plus certainement annulée en faisant un fork comme ça s'était produit avec Ethereum à l'époque où il s'est divisé de ETC. L'autre comme l'explique Perl c'est sur la clef publique diffusée lors d'une transaction, il faut arriver à casser la clef publique avant que la transaction soit minée pour pouvoir s'emparer des fonds avant qu'ils changent d'adresses.
Mais si l'adresse d'envoi a encore des fonds ou est susceptible d'être réutilisée, l'attaque peut certainement réussir avec beaucoup moins de puissance de calcul puisqu'il n'y a plus de limite de temps pour casser la clef publique récupérée. Donc ça pourrait survenir plus tôt pour ce cas de figure.
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There are two main ways in which a quantum computer may pose a threat to the Bitcoin network.43,44
The first and least likely is the threat to the proof of work mechanism (mining) for which a quantum computer may achieve a quadratic speedup on the hashing of the SHA256 protocol with the Grover's algorithm.45
The algorithmic speedup is unlikely to make up for the considerably slower clock cycle times relative to state of the art classical computing for the foreseeable future.44
The second and more serious threat would be an attack on the elliptic curve encryption of signatures.
Bitcoin uses the Elliptic Curve Digital Signature Algorithm (ECDSA) that relies on the hardness of the Elliptic Curve Discrete Log Problem (ECDLP), and a modified version of Shor's algorithm46–48 can provide an exponential speedup using a quantum computer for solving this problem.
Bitcoin uses ECDSA to convert between the public and private keys, which are used when performing transactions.
With best practices (using new addresses for each transaction), the only point at which a public key is available and relevant to a eavesdropper is after a transaction has been broadcast to the network but prior to its acceptance within the blockchain. In this window, transactions wait in the “mem pool” for an amount of time dependent on the fee paid; the time taken for this process is on average 10 min, but it can often take much longer.
https://avs.scitation.org/doi/10.1116/5.0073075 The first and least likely is the threat to the proof of work mechanism (mining) for which a quantum computer may achieve a quadratic speedup on the hashing of the SHA256 protocol with the Grover's algorithm.45
The algorithmic speedup is unlikely to make up for the considerably slower clock cycle times relative to state of the art classical computing for the foreseeable future.44
The second and more serious threat would be an attack on the elliptic curve encryption of signatures.
Bitcoin uses the Elliptic Curve Digital Signature Algorithm (ECDSA) that relies on the hardness of the Elliptic Curve Discrete Log Problem (ECDLP), and a modified version of Shor's algorithm46–48 can provide an exponential speedup using a quantum computer for solving this problem.
Bitcoin uses ECDSA to convert between the public and private keys, which are used when performing transactions.
With best practices (using new addresses for each transaction), the only point at which a public key is available and relevant to a eavesdropper is after a transaction has been broadcast to the network but prior to its acceptance within the blockchain. In this window, transactions wait in the “mem pool” for an amount of time dependent on the fee paid; the time taken for this process is on average 10 min, but it can often take much longer.
