Hash Encryption (or Hashing)
Hashing is a one-way cryptographic operation that transforms data (usually a string or file) into a fixed-length value, typically represented as a sequence of characters (often hexadecimal). The primary purpose of hashing is to ensure data integrity and store data in a way that makes it difficult to recover the original input.

Key Characteristics of Hashing:
One-way process: You can hash data, but it's nearly impossible to reverse the operation (i.e., retrieve the original data).
Fixed-length output: Regardless of the size of the input data, the hash output will always have a fixed length. For example, the SHA-256 hash always produces a 256-bit output.
Deterministic: The same input will always produce the same hash output.
Collisions: A good hash function minimizes the chance of two different inputs producing the same hash value (called a collision).
Common Hash Functions:
MD5 (Message Digest Algorithm 5) – Produces a 128-bit hash value. Although widely used in the past, it is no longer considered secure due to vulnerabilities (collisions).
SHA-1 (Secure Hash Algorithm 1) – Produces a 160-bit hash. It was commonly used but is now considered weak due to collision vulnerabilities.
SHA-256 – Part of the SHA-2 family, produces a 256-bit hash. This is one of the most widely used and secure hash functions today.
SHA-3 – The latest member of the Secure Hash Algorithm family, designed to provide better security than SHA-2.
BLAKE2 – A cryptographic hash function designed as an alternative to MD5 and SHA-2, offering faster speed and security.
Why Use Hashing?
Data Integrity: Verifying that data has not been altered. If even a single character of the original data changes, the hash will change drastically, making it easy to detect tampering.
Password Storage: Instead of storing passwords directly, websites and services hash passwords and store the hash. When users log in, the entered password is hashed and compared to the stored hash.
Digital Signatures: Hashing is used in the creation of digital signatures, where the data is hashed, and the hash is then signed with a private key.
File Deduplication: Hashes are used to compare files for duplicates, as identical files will have identical hashes.