SHA-256
Secure Hash Algorithm 256-bit
Sicheres Hashverfahren mit 256 Bit
SHA-256 is a widely used cryptographic hash function from the SHA-2 family that produces a 256-bit fingerprint from arbitrary data. By current standards it is considered secure and is the de-facto standard for integrity checking, digital signatures and the identification of files. In forensics it is the usual method for evidence preservation.
History & facts. SHA-256 belongs to the SHA-2 family, standardised by the United States of America (US) National Institute of Standards and Technology (USA) (NIST) after the predecessors MD5 and SHA-1 lost their suitability for security purposes through practicable collision attacks. A tiny change in the input completely changes the 256-bit value, and the input cannot be computed back from the hash. Alongside it exists the newer, differently constructed SHA-3 family as a fallback option.
Outlook & recommendation. For integrity and identification, SHA-256 is currently a solid choice; broken functions such as MD5 or SHA-1 should no longer be used for this. An important special case is passwords: these should not be stored with fast hash functions such as SHA-256 alone but with purpose-built, deliberately slow functions and salt, to hinder mass guessing.