[jimwhitson]

IANAL, but I think "knowledge ... a crime" means a particular crime, not a general category. So if you reasonably suspect that your work might be useful to criminals, that's not conspiracy, but as soon as one particular criminal tells you he intends to use your software for a particular crime, you're a conspirator unless you report him to the authorities. So honest cryptographers have nothing to fear, unless a criminal tells them about his crypto-assisted crimes and they don't report it.