Awesome Kata. I have been loving these Simple Encryption Katas and can't wait to get to the last one.

One note for people coming to this kata, everytime you see <==>("against") in the description, it means to swap. I likely overthought this and others may not. Plenty of people have finished this without clarification but if there is anyone like me I hope this helps.

The C# version is almost always throwing an error every time when just returning false and running all tests. It appears to be some issue with the "Random Tests".

Random Tests: System.OutOfMemoryException : Out of memory
STDERR: Stack overflow in unmanaged: IP: 0x5d208c, fault addr: 0x7ff0b2bf9ff8

Code:
public class solution
{
public bool validate(string n)
{
return false;
}
}