Quantum AI Bitcoin
Welcome Avatar! Quantum computing and quantum cryptography have been in the news recently. In the 1980s, Charles Bennett and Gilles Brassard created quantum encryption and have recently been honored with a Turing Award (Nobel Prize of computer science). The lore runs that while swimming off the shore of Degen Island Puerto Rico âDr. Bennett swam up to Dr. Brassard and suggested they use quantum mechanics to create a bank note that could never be forged.â Forty years later, it is poised to become an essential way of protecting the worldâs most sensitive information. If youâve heard of quantum in a cryptocurrencies context, youâre probably aware that thereâs some risk of advances in this field breaking some key security protections we rely on in public blockchains. Today, Google Quantum AI published a whitepaper on The Cost of Breaking Cryptocurrencies. Bears have recently been shouting (again) about quantum computing being the driver of BTCâs recent price performance. Weâll break down whatâs happening so you can come to your own conclusions. Cryptography relies on a mathematical asymmetry: some operations are simply harder to perform than others - or stated another way, some things are easier to âdoâ than âun-doâ. Itâs easier to smash an egg than reassemble the result. Similarly itâs easier to multiply two prime numbers than it is to find the prime factors of a large number. To encrypt a message we combine the plaintext with a key to create ciphertext. Without the key, reversing this process is exponentially more computationally intensive. You can encrypt all the personal data you own with the processing power of a cell phone, but the combined power of all the computers in the world running until the world runs out of energy couldnât decrypt it by brute force. As processing power increased exponentially according to Mooreâs Law, itâs true that some early encryption algorithms with relatively short key sizes became breakable due to faster technology. But adding just 1 bit to the key length doubles the computational cost to break. Therefore the obsolete DES (56 bit) was replaced with Triple-DES (168 bit), 128 bit symmetric ciphers, and eventually the 256 bit cryptography which secures the Internet (and Bitcoin) today. If 256 bit keys were under threat from current computer power, we could simply adopt 512 bit keys. Doubling the key length would double the cost to break 256 times. Thatâs a number too long to write here. Thatâs the simple overview, but the asymmetric property discussed earlier is based on our knowledge of math. Cryptographers extend mathematical knowledge all the time, and some of their discoveries mean that itâs easier to reverse the encryption process. This is a good reason to use key lengths longer than we think necessary. It provides some overhead if, suddenly, a genius discovers a 25% more efficient way to brute force. This has been known for a long time. For example, the quantum search algorithm devised by Lov Grover in 1996 speeds up brute force attacks on symmetric encryption using quantum computing, essentially halving the key length. Shorâs algorithm (1994) is a stronger attack on public key cryptography (websites and crypto), where doubling the key length yields only an 8-fold increase in computing power required to break. If quantum computing ever scales like Mooreâs Law this puts current crypto security in jeopardy. This is a theoretical attack: it took from the year 2001 to the year 2012 to grow the size of the number being factored from 15 (5x3) to 21 (7x3). Yes, similar to how cutting-edge and over-hyped âAIâ canât solve a theme park video game for 12 year olds, the much feared âquantum computingâ canât factor anything larger than two digit semi-primes within the grasp of a grade-school math student. So is this a real threat which merits the attention given by Google, government agencies, and crypto bears - or just another poorly understood tech where the hype/FUD doesnât match reality? Letâs dive in! Encryption schemes can be lumped into two groups - symmetric cryptography and public key cryptography. Groverâs algorithm basically limits the entire effect of quantum computing to halving the key length. In other words if we upgraded every 256 bit symmetric key to 512 bits that would cancel out quantum breakthroughs. Symmetric cryptography as the name suggests requires that an encrypter/signer and decrypter/verifier must possess the secret key. Public blockchains are unworkable with this type of encryption - the key needed to validate that a transaction is correctly authorized would be the same key which could spend all funds from the account. Public blockchains secured by crypto rely on public key cryptography, which as the name suggests allows publishing the public part of the key while only the account owner retains and uses the private key. Public key cryptography also secures the web. And it is public key cryptography which is deeply vulnerable to quantum computing. Now you may have read the argument that if Bitcoin crypto security is broken by quantum, all other (public key) cryptography is also broken and weâd have bigger problems. However symmetric cryptography (not broken by quantum) could replace public key crypto - GSM, the cell phone standard; and Kerberos, the ticket based network authentication protocol from the 1980s - both ran on symmetric crypto. Public blockchains would be uniquely affected with no plausible replacement beyond hash based signatures (which are already being considered in post-quantum blockchain research). Benefits of Quantum Computing This is a tl;dr of what published experts have declared is possible, in theory, if the machines can be built and scaled up. Weâre not quantum scientists: drug discovery, molecular simulations: e.g. protein folding at a rate not possible even with massive distributed computing projects like Folding@Home materials science: quantum simulation of atomic level interactions to design new chemicals Risks of Quantum - Harvest Now, Decrypt Later Nation state level actors (and even some sophisticated organized crime groups) have the technical ability to intercept and store encrypted communications. Once quantum hardware exists: all your financial data, ID documents, private communications, trade secrets, etc are visible. Signature cryptography attacks: a quantum computer running Shorâs algo (above) could theoretically derive the key (simplistically, the seed phrase) to a wallet just from the unhashed public key (address). Look up the biggest holders on the blockchain, save down their address, and try to crack their seed. Something which is impossible now could be trivial with quantum. The only wallets which are theoretically safe are those which have never spent funds, but an attack could be feasible on networks like Bitcoin with a slow block time. Broadcast transaction â sits in mempool â attackers compete to crack your key in under 10 mins (BTC block time) and submit a competing transaction stealing funds The major myth is that quantum can rewrite the blockchain, giving an attacker arbitrary control. This isnât the case, the SHA256 hash which secures the blockchain by including the hash of the prior block in the current block only faces the upper bound of Groverâs algo - an effective reduction to 128 bit key size, still too large to brute force. All serious papers acknowledge this, including Googleâs most recent. Quantum x Bitcoin is back in the news this week due to a paper released by Google. This paper focuses on attacks against the 256-bit Elliptic Curve Discrete Logarithm using secp256k1, the parameters of the elliptic curve used in Bitcoin and Etherum public-key cryptography. The key takeaway is a roughly 10x improvement in the computing resources needed to mount a successful attack, bringing the timeline forward. Interestingly, claims are validated through zero-knowledge proofs. We think this is the first published example in all of information security of a pâŠ
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