SHA-256
also: SHA2, SHA-2, SHA256
SHA-256 is a cryptographic hash function that produces a 256-bit (32-byte) fixed-length digest from any input data. It is widely used for verifying file integrity and security applications.
SHA-256 (Secure Hash Algorithm 256-bit) is part of the SHA-2 family of cryptographic hash functions standardized by NIST. It takes any amount of input data and produces a unique 64-character hexadecimal string, making it useful for detecting even tiny changes in files.
A key property is that SHA-256 is one-way—you cannot reverse the hash to recover the original input. Different inputs almost always produce different hashes (collision resistance), making it ideal for checksums and verification.
Common Linux uses include verifying downloaded ISO images, checking package integrity in package managers, and storing password hashes. For example: sha256sum ubuntu-22.04.iso produces a hash like a3e5f8d2c7b9a1e4f6c8d0e2a4b6c8d0e2a4b6c8d0e2a4b6c8d0e2a4b6