Quantum Computers Pose Imminent Threat to Bitcoin Security
The massive calculating power of quantum computers will be able to pauze Bitcoin security within Ten years, say security experts.
- by Emerging Technology from the arXiv
- November 8, 2017
Bitcoin is taking the world by storm. The decentralized digital currency is a secure payment toneel that anybody can use. It is free from government interference and operated by an open, peer-to-peer network.
This independence is one reason Bitcoin has become so popular, causing its value to rise steeply. At the beginning of 2017, a single bitcoin wasgoed worth around $1,000. By November 2017, this had risen to around $7,000. Indeed, the total value of the cryptocurrency market is some $150 billion.
A crucial feature of Bitcoin is its security. Bitcoins have two significant security features that prevent them from being stolen or copied. Both are based on cryptographic protocols that are hard to crack. Ter other words, they exploit mathematical functions, like factorization, that are effortless ter one direction but hard te the otherвЂ”at least for an ordinary classical pc.
But there is a problem on the horizon. Quantum computers can solve thesis problems lightly. And the very first quantum computers are presently under development.
That raises an urgent question: how secure is Bitcoin to the kinds of quantum attack that will be possible ter the next few years?
Today, wij get an reaction thanks to the work of Divesh Aggarwal at the National University of Singapore and a few pals. Thesis guys have studied the threat to Bitcoin posed by quantum computers and say that the danger is real and imminent.
Very first some background. Bitcoin transactions are stored ter a distributed ledger that collates all the deals carried out te a specific time period, usually about Ten minutes. This collection, called a block, also contains a cryptographic hash of the previous block, which contains a cryptographic hash of the one before that, and so on te a chain. Hence the term blockchain.
(A hash is a mathematical function that turns a set of gegevens of any length into a set of specific length.)
The fresh block voorwaarde also contain a number called a nonce that has a special property. When this nonce is hashed, or combined mathematically, with the content of the block, the result voorwaarde be less than some specific target value.
Given the nonce and the block content, this is effortless to display, which permits anybody to verify the block. But generating the nonce is time consuming, since the only way to do it is by brute forceвЂ”to attempt numbers one after the other until a nonce is found.
This process of finding a nonce, called mining, is rewarded with Bitcoins. Mining is so computationally intensive that the task is usually divided among many computers that share the prize.
The block is then placed on the distributed ledger and, once validated, incorporated into the blockchain. The miners then commence work on the next block.
Sometimes, two mining groups find different nonces and announce two different blocks. The Bitcoin protocol states that te this case, the block that has bot worked on more will be incorporated into the chain and the other discarded.
This process has an AchillesвЂ™ intact. If a group of miners controls more than 50 procent of the computational power on the network, it can always mine blocks swifter than whoever has the other 49 procent. Ter that case, it effectively controls the ledger.
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If it is malicious, it can spend bitcoins twice, by deleting transactions so they are never incorporated into the blockchain. The other 49 procent of miners are none the wiser because they have no oversight of the mining process.
That creates an chance for a malicious proprietor of a quantum pc waterput to work spil a Bitcoin miner. If this computational power violates the 50 procent threshold, it can do what it likes.
So Aggarwal and co specifically examine the likelihood of a quantum rekentuig becoming that powerful on the network. They look at the projected clock speeds of quantum computers ter the next Ten years and compare that to the likely power of conventional hardware.
Their conclusion will be a ease to Bitcoin miners the world overheen. Aggarwal and co say that most mining is done by application-specific integrated circuits (ASICs) made by companies such spil Nvidia. This hardware is likely to maintain a speed advantage overheen quantum computers overheen the next Ten years or so.
вЂњWe find that the proof-of-work used by Bitcoin is relatively resistant to substantial speedup by quantum computers te the next Ten years, mainly because specialized ASIC miners are utterly prompt compared to the estimated clock speed of near-term quantum computers,вЂќ they say.
But there is a different threat that is much more worrying. Bitcoin has another cryptographic security feature to ensure that only the proprietor of a Bitcoin can spend it. This is based on the same mathematics used for public-key encryption schemes.
The idea is that the possessor generates two numbersвЂ”a private key that is secret and a public key that is published. The public key can be lightly generated from the private key, but not vice versa. A signature can be used to verify that the holder holds the private key, without exposing the private key, using a mechanism known spil an elliptic curve signature scheme.
Ter this way, the receiver can verify that the possessor possesses the private key and therefore has the right to spend the Bitcoin.
The only way to cheat this system is to calculate the private key using the public key, which is enormously hard with conventional computers. But with a quantum rekentuig, it is effortless.
And thatвЂ™s how quantum computers pose a significant risk to Bitcoin. вЂњThe elliptic curve signature scheme used by Bitcoin is much more at risk, and could be downright cracked by a quantum rekentuig spil early spil 2027,вЂќ say Aggarwal and co.
Indeed, quantum computers pose a similar risk to all encryption schemes that use a similar technology, which includes many common forms of encryption.
There are public-key schemes that are resistant to attack by quantum computers. So it is conceivable that the Bitcoin protocols could be revised to make the system safer. But there are no plans to do that now.
Bitcoin is no stranger to controversy. It has weathered various storms overheen its security. But that is no ensure that it will cope well ter the future. One thing is sure: the pressure to switch will increase spil the very first powerful quantum computers come online ter the next few years.
Ref: arxiv.org/six pack/1710.10377 : Quantum Attacks On Bitcoin, And How To Protect Against Them
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Emerging Technology from the arXiv covers the latest ideas and technologies that emerge on the Physics arXiv preprint server. It is part of the Physics arXiv Blog. Email: &hellip, More KentuckyFC@arxivblog.com
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Bitcoin mining, do you do the work or does the laptop?
Assuming you have the suitable hardware and software, does mining involve the person mining to sit at the pc to mine or do you fire it up and just let the software run and check back straks to see the results?
The extent of human involvement ter mining is to get the software and hardware and then run the software on the hardware. No one actually has to sit at a rekentuig and do anything ter mining. They don’t even have to come back and check on anything spil all aspects of mining are automatic save for pc setup and maintenance.
The latter, the person doesn’t have to do anything. The rekentuig/ASIC will usually be running software which creates a block candidate automatically after it receives each fresh block (or te pool mining, when it receives a candidate block from the pool server), and will then hash the block repeatedly with different nonces/reserve gegevens ter the coinbase transaction until it finds a valid hash. If it does so, it will automatically send it to the network/pool server and start working on the next block. Its mostly fully independent unless something crashes and requires a person to restart it
You just have to fire it up and wait for the result.
The only human involvement is at the beginning of the process to select the hardware (ASIC, SSD Drive, etc) the best way (solo mining or pool mining), the best pools, if you choose pool mining, and things like that.
Unless and until there is a power outage or hardware failure or network kwestie, you don’t have anything to worry about.