SHA-2 is not good enough for password because, like most general purpose hashes, it's fastDesigned by NSA SHA-256 outputs 32 bytesSHA-512 outputs 64 bytesIntel extended x86 to include SHA operations in hardwareSHA-2 FamiliesSHA256SHA-224SHA-384SHA-512 Is MD5 considered insecure?Using salted md5 for passwords is a bad idea. Not because of MD5's cryptographic weaknesses, but because it's fast. This means that an attacker can try billions of candidate passwords per second on a single GPU. What you should use are deliberately slow hash constructions, such as scrypt, bcrypt and PBKDF2.https://security.stackexchange.com/questions/19906/is-md5-considered-insecure