Secure hashing algorithms (SHA) organize digital data into smaller packages and are used to authenticate messages. They are important for protecting proprietary methods and sensitive data. SHAs are implemented through hardware or software, and the US government has standardized at least six algorithms. The SHA-2 family is more robust than SHA-1 and a new algorithm, SHA-3, is being developed through a public competition.
A secure hashing algorithm, often known simply as “SHA”, is a hashing algorithm that is considered cryptographically secure. In general, hashing functions are used to sort and organize digital data into smaller, more categorized packages. Algorithms are the programs that drive functions, and the security of these algorithms is important as it controls how easily data can be unlocked and rearranged. How secure things need to be usually depends on the circumstances. Many software and code developers want impenetrable algorithms because their methods for ordering arguments and drawing connections are proprietary and they use them to make money. In other cases the data itself is highly sensitive, as is often the case with things like medical records or certain government documents. The actual mechanisms of SHAs tend to be very complicated, and at least some degree of technical expertise is usually required to fully understand how they work and how they are developed. Like most things tech, there has also been an upward evolution in development; older models have largely been superseded, and newer, safer designs are being introduced almost constantly.
Understanding of hash algorithms in general
The modern digital landscape contains hundreds of millions of data points, all of which occupy a web of interconnections and commonalities, both across websites and in the social sphere when it comes to user-generated messages and posts. Hashing is a way of amalgamating similar or related data in such a way that it forms a sort of compendium or a smaller, more related “web within a web”. Secure hashing algorithms try to do this by organizing themselves efficiently and securely.
The original data, once hashed by a SHA, typically cannot be reconstructed without a huge amount of computing power. Secure algorithms are often used in conjunction with other algorithms to authenticate messages, including digital signatures.
How they are implemented
Some routers and network firewalls implement SHAs directly into their hardware. This allows data packets to be authenticated with little impact on throughput. Specially designed software is another option, including many open source implementations. For example, the US National Institute of Standards and Technology (NIST) and the Canadian Communications Security Establishment (CSE) jointly administer the Cryptographic Module Verification Program (CMVP). This official program certifies the proper functioning of secure algorithm implementations for sensitive applications.
Standardization
The US government has standardized at least six secure hash algorithms. SHA-0 and SHA-1 were the first models developed in the 1990s. The SHA-2 series developed in the 2000s included SHA-224, -256, -384 and -512. These are designed in such a way that two documents with different contents generally produce two unique sets of hash values, which is really helpful in terms of avoiding hash collisions.
The first iterations
The SHA-0 algorithm, first published in 1993 by NIST, was quickly discontinued after a significant weakness was found. It was superseded by SHA-1 in 1995, which includes an additional computational step that addresses SHA-0’s undisclosed issues. Both algorithms hash a message up to 264-1 bits into a 160-bit digest. Both use a 512-bit block size and a 32-bit word size in their operation.
SHA-1 is used in some common Internet protocols and security tools. These include IPsec, PGP, SSL, S/MIME, SSH and TLS. SHA-1 is also typically used as part of the security scheme for unclassified government documents. Some parts of the private sector also use this algorithm for some sensitive information. It was formally withdrawn from government use in 2010, however.
Continuous evolution and development
SHA-224, -256, -384 and -512 were published by NIST between 2001 and 2004. These four algorithms, also known as the SHA-2 family, are generally more robust than SHA-1. SHA-224 and SHA-256 use the same maximum input message, word, and block size as SHA-1. Conversely, SHA-224 produces a 224-bit digest, while SHA-256 produces a 256-bit digest. SHA-384 and SHA-512 increase the block size to 1024 bits, the word size to 64 bits, and the maximum input message length to 2128-1 bits. The digest produced by SHA-384 is 384 bits long, while the SHA-512 digest contains 512 bits.
Like SHA-0 and SHA-1, the SHA-2 family was designed by the United States National Security Agency (NSA). Although serious flaws in SHA-2 have not been publicly disclosed, NIST has opened a competition to develop the next secure hashing algorithm. This new algorithm, which will be called SHA-3, will probably be chosen from a collection of public entries. It should be a new design, not based on existing algorithms.
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