SHA-224 is part of SHA-2 family which consists of six hash functions. SHA-224 has digest length of 224 bits. In February 2004, SHA-224 was published as an additional variant, which was defined to match the key length of two-key Triple DES. SHA-224 is pretty much identical to SHA-256 except the fact that the initial hash values h0 through h7 are different and the output is constructed by omitting h7. SHA-224 is basically a truncated version of SHA-256.