SHA256 (Secure Hash Algorithm 256-bit) is a cryptographic hash function that generates a fixed-size, 256-bit (32-byte) hash value from an arbitrary amount of input data. It is part of the SHA-2 (Secure Hash Algorithm 2) family, which was designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST) in 2001.
Key characteristics of SHA256:
1. Fixed Size Output: Regardless of the size of the input data, the output hash is always 256 bits (32 bytes).
2. Deterministic: The same input will always produce the same hash value.
3. Fast Computation: Hashes can be computed quickly, which is crucial for many applications.
4. Pre-image Resistance: It is computationally infeasible to reverse the hash function, meaning you can't derive the original input from its hash value.
5. Collision Resistance: It is very difficult to find two different inputs that produce the same hash value.
6. Avalanche Effect:A small change in the input produces a significantly different hash, which enhances security.
SHA256 is widely used in various security applications and protocols, including SSL/TLS, Bitcoin, and various encryption algorithms. It is essential for ensuring data integrity and securely transmitting data over networks.