What is Cryptographic Hash ? A cryptographic hash function is an algorithm that can be run on data such as an individual file or a password to produce a value called a checksum. The main uses of a cryptographic hash function are to verify the authenticity of a piece of data. Some commonly used cryptographic hash functions include MD5 and SHA-1 although many others also exist. Cryptographic hash functions are designed to prevent the ability to reverse the checksums they create back to the original texts and hash functions are extremely useful and appear in almost all information security applications. A hash function is a mathematical function that converts a numerical input value into another compressed numerical value. The input to the hash function is of arbitrary length but the output is always of fixed length.
Certain properties of cryptographic hash functions impact the security of password storage.
Cryptography is a method of protecting information and communications through the use of codes, so that only those for whom the information is intended can read and process it. The prefix “crypt-” means “hidden” or “vault” — and the suffix “-graphy” stands for “writing.”
In computer science, cryptography refers to secure information and communication techniques derived from mathematical concepts and a set of rule-based calculations called algorithms, to transform messages in ways that are hard to decipher. These deterministic algorithms are used for cryptographic key generation, digital signing, verification to protect data privacy, web browsing on the internet, and confidential communications such as credit card transactions and email.
Non-reversibility, or one-way function. A good hash should make it very hard to reconstruct the original password from the output or hash.
Diffusion, or avalanche effect. A change in just one bit of the original password should result in a change to half the bits of its hash. In other words, when a password is changed slightly, the output of enciphered text should change significantly and unpredictably.
Determinism. A given password must always generate the same hash value or enciphered text.
Collision resistance. It should be hard to find two different passwords that hash to the same enciphered text.
Non-predictable. The hash value should not be predictable from the password.
Cryptographic hash functions do provide barriers to attackers, like speed bumps slowing down a speeding motorcycle but it’s critical to remember that eventually, the motorcycle will still make it down the street. However, these barriers will slow down your defenders as well—normal users and your server. Set the speed bump too high, and you run the risk of annoying your user—and overtaxing your server.
What is Cryptographic Hash
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