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Hashing and Cryptographic Hash Functions

What Are Cryptographic Hashes?

If you’ve found yourself wondering what exactly hashing is, it’s essentially a mathematical algorithm mapping and compressing data. This can be any data – a name, date of birth, a file, or a transaction. The data can be any size during this process, from something as big as 200 megabytes to as small as a single character. Hashing creates a code representation for the data using a hash algorithm, and the code acts as a string of characters and becomes a fingerprint of the file.

The basic concept of hashing is that it gives data a digital identity similar to a fingerprint. Just as with the fingerprints on your hand, it’s a unique identifier and holds a massive amount of data. The data output size is always the same, no matter how large the input was in the beginning. Whether you need to hash an entire book or just one line of text, if the output, or value, is 64, both the chapter and sentence will end up in a code string of 64 hexadecimal characters in the case of a 256-bit hash.

What’s a Hash Function?

Cryptographic hash functions are the mathematical algorithm itself and have many security authentication applications. These are found in digital signatures and message authentication codes (MACs) and other forms of authentication. In addition, they can be used as ordinary hash functions for indexing data in hash tables, in the detection of duplicate data and/or data corruption, and for fingerprinting. Hash functions are often referred to as hash value, hash code, digest, and checksums, even though they all stand for more general functions with different properties and purposes. The hash value is the fingerprint of the information, and once a hashing function is applied to any data, the output receives a hash value.

hash function

For a hash function to be valuable and secure, it should have ideal properties such as: 

  • Speed: It must be fast. The hash function should be able to produce a hash in a fraction of a second.
  • Deterministic: Meaning no matter how many times you use a hash function for the same input, you’ll always get the same output. 
  • Uniformity: Taking the same amount of hashing across the data, no matter the size. 
  • Fixed-size: The output will be a fixed size (such as 64 characters). 
  • Functions must not be reversible: They should only act as a one-way function and shouldn’t be able to be inverted. If you hash a password it should not be possible to arrive at what the password is based on only the hash of it.
  • Avalanche effect: The data output changes drastically if any of the information changes, even if it’s a single character that changes.

Cryptographic hash functions must be able to withstand all cryptanalytic attacks. This means it must be pre-image resistant (not reversible), second pre-image resistant (not able to find a input to produce a second equal hash when the first input is known), and collision-resistant (not produce two equal hashes based on two freely chosen inputs).

Secure Hashing Algorithms (SHA)

Hash algorithms are comprised of different families, with the core difference being the hash value they produce and the security properties it uses. The four classes of the most prominent family of hash functions are:

  • SHA-0
  • SHA-1
  • SHA-2
  • SHA-3

SHA-0 and SHA-1 are now obsolete, but SHA-2 consists of four family members: SHA-224, SHA-256, SHA-384, and SHA-512. The ending number on each of these is the number of bits of their hash values. 


Other Cryptographic Hash Algorithms

  • MD5
  • RIPEMD-160
  • Whirlpool
  • BLAKE2
  • BLAKE3

Many hash functions should not be used due to the vulnerabilities found in them. 

Hashing and Cryptocurrency

Cryptocurrency blockchains deal with a large number of transactions; therefore, they use hashes.

SHA Encryption

To date, there hasn’t been a successful attack on these algorithms, but with the constant increase in threats, the cybersecurity world will continue to improve these algorithms. 

At the end of the day, the average person doesn’t really need to know about hashing except for the fact that it’s a security function used in encryption algorithms. The DataLocker team is dedicated to the ongoing support of cybersecurity, so let us handle these types of issues or answer more of your questions. To learn more about our products and services to help you with device and software security, visit us at www.datalocker.com.