After digging deeper into this subject I was able find a little more information that may be helpful (Some of this is translated from Chinese, so while jumbled a bit, it looks like there are some clues that might help get you past the problem you are having generating key pairs:) It is difficult to find information on this as “The code in UnrealPak was mostly meant to be a quick test when developing the pak encryption…”
"I suggest using one of the available online options for generating these keys. You can easily find a page to check if a big number is prime (P and Q should be prime) and there’s a few solutions that will generate the key pairs online too (and they’re much faster).
That creates a very large number of random numbers whose value can be designated to test the key pair… Other online tools do not recommend that you use the -sing = filename"
" … it is difficult to give a specific recommendation tools to find the n-th prime number to find two moderately large values in the order specified by a handful of sites, etc. (ie 1,000,000,000,000 29,996,224,275,833 first minority) on the command line
-GenerateKeys = Filename -P {first} -Q {decimal} second minority
.ssby using a key pair made -sign = filename to the four innings. If you are certain that you use a valid one in two minority here, you can shorten the process by using the keys to make -NoVerifyPrimes options.
As the value added by entering the area {} minority use the Hex value."