Crypto is munitions for export purposes, I doubt you can get a ruling that it qualifies for 2A protection. The law is like that. The law can classify a thing as one thing for one purpose, and another thing for another purpose. If they want to ban crypto, they could classify it as a Schedule I drug and it'd make about as much sense as classifying it as a munition.

"Sir, you're going to need an ID, a fingerprint card, and approval from the FBI before you can download that browser."

2A isn't upheld any more than 4A. States will just require a license for crypto and make it "may-issue". RSA will be classified an "assault algorithm" and banned in California. You'll have to pay a $200 tax stamp for each key, message capacity will be limited to 10 characters, and if your ex-wife claims you hit her then the sheriff can confiscate your hard drives until you convince a judge you didn't.