SHA-256 (Secure Hash Algorithm 256-bit) is a widely used cryptographic hash function that generates a 256-bit signature for a text, used in Bitcoin proof-of-work (PoW).
SHA-256 is a part of the SHA-2 (Secure Hash Algorithm 2) family of cryptographic algorithms, which were developed by the National Security Agency (NSA) in the United States.
SHA-256 takes an input of any length and produces a fixed-size 256-bit (32-byte) hash value. The output, commonly referred to as the hash, is a unique representation of the input data. Even a small change in the input will produce a significantly different hash value.
The SHA-256 algorithm is extensively used in various fields, particularly in the realm of cryptocurrencies. Bitcoin, for example, utilizes SHA-256 as the underlying hashing algorithm for mining and securing its blockchain network.
In the context of Bitcoin mining, SHA-256 is employed to hash the block header, which contains information about the block, including the transactions, timestamp, and previous block’s hash. Miners attempt to find a hash value that meets certain criteria defined by the network, such as having a specific number of leading zeros.
The SHA-256 algorithm is designed to be computationally intensive, making it difficult to reverse-engineer the input data from the hash output. It is considered a secure and reliable hash function, widely adopted for data integrity, password storage, digital signatures, and other cryptographic applications.
The strength of SHA-256 lies in its resistance to collision attacks, where two different inputs produce the same hash value. While collisions are theoretically possible, they are computationally infeasible to find in practice.
Overall, SHA-256 plays a crucial role in ensuring the security and integrity of various systems and cryptocurrencies, including Bitcoin, by providing a secure and unique representation of data.