High Quality Content by WIKIPEDIA articles! In NSA terminology, a Type 4 algorithm is an encryption algorithm that has been registered with NIST but is not a Federal Information Processing Standard (FIPS). Type 4 algorithms may not be used to protect classified information.Alternatively, some sources use 'Type 4' specifically to refer to exportable algorithms - once limited to 40-bit keys - which can be relatively easily broken with even a modest amount of computing power.