SHA-256 is part of SHA-2 family which consists of six hash functions. SHA-256 has digest length of 256 bits. SHA-256 is computed with 32-bit words. Several cryptocurrencies like Bitcoin use extensively SHA-256 for verification of transactions and calculation of proof of work. Currently, the SHA-256 has best public attacks break collision resistance for 46 out of 64 rounds and preimage resistance for is 52 out of 64 rounds. It generally partakes in the DKIM message signing standard and in the process of authenticating Debian software packages.