When parties share a secret symmetric key (e.g., upon a successful execution of a key- establishment scheme as specified in [1] and [2]), it is often the case that additional keys will be needed (e.g. as described in [3]). Separate keys may be needed

This Recommendation specifies two methods, called FF1 and FF3-1, for format-preserving 108 encryption. Both of these methods are modes of operation for an underlying, approved symmetric109 key block cipher algorithm. Compared to the original versio