you know i'm leaning more and more towards roger's opinion here knowing what we know about the sources i think it's implied that ibm re invented dc but it's not unambiguous and it's really not such a critical point to this article i think we should just say that ibm was aware of differential cryptanalysis but didn't publish it at least in this article the proper place to get into this in detail would be in the data encryption standard article or the differential cryptanalysis article juicetalk