The argument for needing encryption is very similar to the argument for needing firearms (without getting into the veracity of that need), so you've made a grea

The argument for needing encryption is very similar to the argument for needing firearms (without getting into the veracity of that need), so you've made a great comparison here. One could argue that firearms for personal defense and encryption for personal privacy/security would be completely unnecessary if the state could prevent all crimes that necessitate their use, but they do not and never can. At the same time, the same encryption technology can be used for criminal images, terrorism and other criminal communications. The same goes for firearms being used for homicide, terrorism and other crimes. To prevent all of these, or at the very least reduce their occurrence, crippling the ability of the average citizens to protect themselves is necessary. You also cannot put the genie back in the bottle. Encryption has been made widely available, as have firearms. If we try to remove them now, they will both still be available to individuals, but only ones willing to break the law. To work with your simile(?), banning the AR-15 (and similar black rifles) would be more like banning AES than encryption at large. Other ones would take its place, and be no less lethal or capable of criminal use. For example, here in Canada, we restricted the AR-15 and variants but other just as deadly weapons simply took its prominence as a non-restricted weapon. For the uninitiated, restricted weapons may only be used at a range, require a permit to transit (down to the route you may use, these are only approved for transit to a range or when you are moving), must be entered in a registry, and require greater RCMP clearance to possess. I'm not sure what side of this debate I sit on. It's a very difficult one and I doubt we will ever come to a consensus.