The NSA designed the SHA-256 algorithm along with the other SHA-2 cryptographic hash functions. The initials stand for Secure Hash Algorithm. A cryptographic hash function is a mathematical operation that runs on digital information. The output you get from executing an algorithm is known as a “hash,” and by comparing this to a hash value that is known and expected, it’s easy to tell whether the information has integrity. You can generate a one-way hash from any piece of data, but it doesn’t work the other way you can’t get the data by manipulating the hash.
History
The SHA-256 algorithm is also known as SHA-2, in lieu of the fact that it succeeded SHA-1. It isn’t a lot more difficult to encode than SHA-1 as, but it has a cast-iron 256-bit key which, to date, hasn’t ever been broken.
Websites and web services can communicate securely thanks to files called certificates which set up and verify secure connections. There are cryptographic elements in the certificates that will have been created using the SHA-256 algorithm (and others).
In the past, certificates were usually produced with SHA-1 as digital signature items, but the algorithm was gradually compromised and few people trusted it. This led to a big migration towards a safer class of certificates that used the new SHA-256 algorithm.
The Shift to SHA-2
The SSL certificate industry moved to SHA-2 in 2016. This has meant that thousands of certificates and big software updates have needed to be implemented by centralized trusted certification authorities.
New certificates had to be produced by the deadline of 31 December 2015. Everyone in the Internet sector was required to move to the new standard by this date, but of course, mistakes were made.
Over the next couple of years, most Sha-1 certificates will be gone. In August 2017, there were around 500,000 left.
SHA-3-Encryption—The Next Big Leap
Cyberattacks are expected to increase as computer processing power becomes cheaper to obtain, and this means that as time goes on, digital signatures that are considered adequate today won’t be as secure in the face of increased future threats. The likes of the SHA-2 algorithm will be obsolete.
That’s why choosing the right algorithm will be so critical. Relying on workarounds won’t be enough. The truth is that these days no hashing algorithm has a shelf life of more than 10 years, which is why cryptographers have already completed work on SHA-3, the replacement for the SHA-2 algorithm. When it comes time to move to a safer standard, SHA-3 will be there and ready to take up the fight.
Creating new cryptographic standards takes many years of research and testing. Only then can work begin on developing software that supports them. It’s only by moving ahead of the threats that we are able to talk about the effectiveness of new levels of security.
Bitcoin and the SHA-256 Algorithm
During the spring of 2002, NSA came up with the first version of the SHA-256 algorithm. After a few months, the national metrological University published this newly-announced encryption protocol and the FIPS PUB 180-2 secure data processing standard was adopted at the Federal level. At the end of 2004 the second version of the algorithm was produced.
Over the following 3 years, the NSA put out a second-generation SHA patent under Royalty-free license. This is why the technology was picked up in the civilian arena.
This Protocol works with information that’s divided into chunks of 512 bits/64 bytes (they’re the same). It makes its cryptographic moves and then puts out a 256-bit hash code. The algorithm repeats a simple round a total of 64 times.
Also, SHA-256 algorithm has some good technical parameters:
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block size indicator (byte): 64.
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maximum allowed message length (bytes): 33.
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digest size characteristics of the message (bytes): 32.
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the standard word size (bytes): 4.
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internal position length parameter (bytes): 32.
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the number of iterations in a single cycle: 64.
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Protocol speed (MiB/s): around 140.
The SHA-256 algorithm relies on the Merkle-Damgard construction method, which stipulates that the initial index be divided up into blocks as soon as the change is made, and those, in turn, into 16 words.
The Bitcoin network uses the SHA-256 algorithm for proof of work in mining and to make bitcoin addresses more private and secure.
