Sorry, I was going by Wikipedia, which says NTLMv2 uses MD5. There is no native MD4 implementation in ABL; you're stuck with MD5, SHA1 and Progress' own ENCODE function. You could roll your own function I suppose, but I think that's a lot more trouble than it's worth and at that point you need a general purpose language rather than a business language so ABL isn't really your best bet. Of course, another option is to use an OS crypto library that does have MD4 functions and declare them as external procedures.