What is SHA256?
SHA256 (Secure Hash Algorithm) is a common cryptographically hash function that translates any input into 256 bits. It is important to notice that any arbitrary data (be is a 4 bytes string, an image or a 10GB movie) will be hashed into 256 bits. SHA256 is deterministic, this is, always output same result given same input
What is SHA256 output?
SHA256 algorithm will hash inputs into 128 bits. Usually the most common way choosen to represent those 128 bits is using hexadecimal notation, that is, grouping the bits in groups of 4 bits, which ends up being a string of 32 characters.
As an example, SHA256("world") = 486ea46224d1bb4fb680f34f7c9ad96a8f24ec88be73ea8e5a6c65260e9cb8a7
How is SHA256 used?
SHA256 is the most used cryptographically hash function nowadays. Lots of passwords managers rely on saving multiple rounds of SHA256 hash since brute force attacks with current hardware are still not successful.
SHA256 is widely used also to prevent data tampering and several cryptocurrencies (including Bitcoin) use this hash function to verify transactions
History of SHA256
SHA256 was introduced by the National Securty Agency (NSA) in 2001. It included sevaral changes from its predecessor, SHA1. SHA2 family of functions include 6 different hash functions that are, SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224 and SHA-512/256 based in the number of bits of the final answer.