Type 4 encryption
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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.