SHA is a Cryptographic Language whose initials stand for “Secure Hash Algorithm”. It was originally designed by the United States National Security Agency. The initial SHA was known as SHA-1 and it produces a standard 160-bit or 20-byte hash value. This is referred to as the message digest.
SHA-256 is a later version of the Cryptographic Hash Algorithm. A message-digest or cryptographic hash can be assigned to text or data files. SHA-256 produces a 256-bit or 32-byte signature for a text.
A hashing algorithm is a mathematical function that turns information into a fixed size. Hashes help computers to identify or compare files or strings of data and it’s more convenient for a computer to compute a hash than it is the original file.
The SHA-256 file compression function works on a 512-bit message block and a 256-bit intermediate hash value. SHA-256 is a 256-bit block cipher algorithm. It uses encryption on the intermediate hash value.
It employs a message block as a Key. SHA-256 has two separate functions:
One- SHA-256 file compression functions.
Two- SHA-256 messaging schedule.