Hashing is the process of using a hash function in computing and cryptography that converts data into a fixed-sized string of characters, typically a sequence of letters and numbers. For example, the operating system on your pc stores passwords as hashes. The operating system uses a hashing function to hash your password and stores it in a database. Whenever you log in, the OS hashes your entered password, compares it with the hash stored in the password database, and logs you in if they match. For added security, the operating system salts the hashes. Salting is the process of adding a random string to the password before hashing it. Hashing is a one-way process. That means you cannot take a hash and recover the original data.
Hashing is also used for keeping data integrity. Data integrity means that the data has not been altered or corrupted during storage or transmission. Before you send or copy data to a removable medium, the hash value is computed using a hash function. Later, when the data is received, the hash value is recomputed. If the hash values match, the data is intact. If it does not match, the data is altered or corrupted.
For example, if you are sending video footage as evidence on a flash drive, you can hash it and save the hash value. Once it reaches the target, it can be hashed again and compared with the original hash value to check whether the file has been tampered with. If the hash value differs, the file is evidently corrupted in transit.
Functions used for hashing.
There are different functions operating systems use for hashing.
MD5 (fast, but not secure for cryptographic purposes)
SHA-256 (secure and widely used)- By defalut , windows uses SHA-256
SHA-512 (even stronger)
Hashing is one of the best ways to keep data integrity. It is irreversible, deterministic ( same input always give same hash), and Fast.
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