although there are but a handful of quantum computing algorithms, one of the most famous ones, Shor’s algorithm, allows for the quick factoring of large primes. Therefore, a working quantum computer could, in theory, break today’s public key cryptography.
.. The NSA announced in 2015 that it was moving to implement quantum-resistant cryptographic systems. Cryptographers are working on quantum-resistant cryptography, and there are already blockchain projects implementing quantum-resistant cryptography. The Quantum Resistant Ledger team, for example, is working on building such a blockchain right now.
What makes quantum-resistant or “post-quantum” cryptography, quantum resistant? When private keys are generated from public keys in ways that are much more mathematically complex than traditional prime factorization.
As we all know the Australian scammer Craig Wright produced a similar PGP message with a fake backdated PGP key. We know that key is a fake for a lot of reasons, including the fact that it doesn’t match the Wayback Machine’s Jan 2011 snapshot of bitcoin.org.
And yes, I signed that message with a different key too. But I have an explanation: you see, I stored all the Satoshi Nakamoto pseudonym stuff on a MicroSD card, which I lost in a tragic house fire right after Gavin visited the CIA. But you see, I actually had to delay the publication of Bitcoin a few months when I realised I needed to add smart contracts to it, and I just found a backup from that attempt. I uploaded it to the Internet Archive a few months prior to releasing Bitcoin:
By consistently timestamping all Internet Archive content, we make attacks like the above easy to detect. The OpenTimestamps proofs we’ve generated are traceable back to the Bitcoin blockchain, a widely witnessed data structure with timestamps that can’t be backdated. Even with a sysadmin’s help, the best the attacker could do is create a modified file that’s very suspiciously missing a timestamp that all other files have.
In cryptography, the avalanche effect refers to a desirable property of cryptographic algorithms, typically block ciphers andcryptographic hash functions. The avalanche effect is evident if, when an input is changed slightly (for example, flipping a single bit) the output changes significantly (e.g., half the output bits flip). In the case of high-quality block ciphers, such a small change in either the key or the plaintext should cause a drastic change in the ciphertext.
In the 1950s, a group of scientists spoke out against the dangers of nuclear weapons. Should cryptographers take on the surveillance state?
.. I spoke to Rogaway about why cryptographers fail to see their work in moral terms, and the emerging link between encryption and terrorism in the national conversation. A transcript of our conversation appears below, lightly edited for concision and clarity.
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Kaveh Waddell: Why should we think of computer science as political—and why have many considered it to be apolitical, for so long?
Phillip Rogaway: I think that science and technology are inherently political, and whether we want to think about it that way or not, it’s the nature of the beast. Our training as scientists and engineers tends to deemphasize the social positioning of what we do, and most of us scientists don’t give a whole lot of thought to how our work impacts society. But it obviously does.
.. There is a tradition, especially in physics, of activism. But computer scientists have not tended to be active in the political sphere.
.. Rogaway: My sense is that politics is there, whether one acknowledges it or not. When you have an ostensibly apolitical department, but you scratch beneath the covers and discover that three-quarters of the faculty are funded by the Department of Defense, well, in fact that’s not apolitical. That is very much working in support of a particular ethos, and one simply hasn’t called it forth.
.. Rogaway: In principle, the tenure process should free academics who have already been tenured to venture out and question matters in a way that could offend power. In practice, it doesn’t seem relevant. By the time a faculty member is tenured, it’s likely that his or her way of seeing the world will have already been so set that they’re very unlikely to become political at that point if they haven’t been already.
.. Anyone who really wants to encrypt their communication is going to find a method for doing so, whether it’s bundled with mass-market products or not. When you make encryption harder to get for ordinary people, you don’t deny it to terrorists. You just make the population as a whole insecure in their daily communications.
.. These aren’t somehow the dark times for either law enforcement or intelligence. These are the times of extraordinary information. Nowhere in history has it been so easy to learn so much about everybody. So, in some sense, we’re really talking about protecting the smallest remnants of remaining privacy.
.. Fortunately, criminal behavior has never been such a drag on society that it’s foreclosed entire areas of technological advance.
.. Rogaway: I think that when you’re hiring faculty members at a public university, that it’s fair game to ask them what their social views are, their views of social responsibility of scientists. I think you have to be careful in how you do this that you’re not applying some kind of political test, that the candidates’ political opinions match up with your own.
But part of the purpose of the public university, land-grant universities like my own, is to serve the public welfare. And if a faculty candidate doesn’t believe that that’s a part of the purpose of his or her work at all, then I think that that’s not appropriate.
.. Rogaway: It’s perfectly practical, in the sense that you can be a successful faculty member without accepting DoD funding. You won’t have as many students, you won’t be able to support as large a research group. And in some areas of computer science, and I’m sure in some areas more broadly, the vast majority of funding may be from the DoD.
I remember speaking to a computer architect, asking if there was any person in computer architecture he was aware of that wouldn’t take DoD money, and he said there was not. And he didn’t really believe that such a person could exist and be successful in the field, as there is no access to adequate resources just from the [National Science Foundation], say.
In my own area, cryptography, I think one can do fine living just on NSF money. But you won’t have a group of 10 students, or something.
CRC Press has generously given us permission to make all chapters available for free download.
The blockchain lets people who have no particular confidence in each other collaborate without having to go through a neutral central authority. Simply put, it is a machine for creating trust.
.. One idea, for example, is to make cheap, tamper-proof public databases—land registries, say, (Honduras and Greece are interested); or registers of the ownership of luxury goods or works of art. Documents can be notarised by embedding information about them into a public blockchain—and you will no longer need a notary to vouch for them.
.. A trusted private ledger removes the need for reconciling each transaction with a counterparty, it is fast and it minimises errors. Santander reckons that it could save banks up to $20 billion a year by 2022. Twenty-five banks have just joined a blockchain startup, called R3 CEV, to develop common standards, and NASDAQ is about to start using the technology to record trading in securities of private companies.
.. These new blockchains need not work in exactly the way that bitcoin’s does. Many of them could tweak its model by, for example, finding alternatives to its energy-intensive “mining” process, which pays participants newly minted bitcoins in return for providing the computing power needed to maintain the ledger. A group of vetted participants within an industry might instead agree to join a private blockchain, say, that needs less security. Blockchains can also implement business rules, such as transactions that take place only if two or more parties endorse them, or if another transaction has been completed first.
.. The spread of blockchains is bad for anyone in the “trust business”—the centralised institutions and bureaucracies, such as banks, clearing houses and government authorities that are deemed sufficiently trustworthy to handle transactions. Even as some banks and governments explore the use of this new technology, others will surely fight it. But given the decline in trust in governments and banks in recent years, a way to create more scrutiny and transparency could be no bad thing.
.. The notion of shared public ledgers may not sound revolutionary or sexy. Neither did double-entry book-keeping or joint-stock companies. Yet, like them, the blockchain is an apparently mundane process that has the potential to transform how people and businesses co-operate
SHA-1 and SHA-256 are cryptographic hash functions. They take as input an arbitrary sequence of bits — and only that. There is no “salt” in hash functions.
When a hash function is said to be “salted”, then this is not a hash function; this is some other construction that uses, among its input parameters, one that is deemed to be a “salt”, and that may use, internally, a hash function as a building element.