The technology behind bitcoin could transform how the economy works

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

 

Is it possible to salt the SHA1 or SHA256 hash function of OpenSSL?

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.