It seems that the maximum Microsoft’s RSA provider supports is 2048 bits: Is there a limit for RSA key exponents in .NET?
I’ve just been been experimenting with 3072 and 4096 bit keys without success. Error message is “Bad Data” !
Nice one Microsoft! Thanks for you concern about security!
Surprising since NIST’s recommendations are that 3072 bit keys are required “if security is required beyond 2030”