Greg Kumparak:
Basically: Unless Apple is omitting something or there’s some backdoor tucked into their many-layers-deep encryption (which, while unlikely, isn’t inconceivable) they really can’t read your iMessages without a fairly insane amount of effort. Sure, they could theoretically brute force their way past your private key. Or they could scrap the entire system and replace it with something with glaring security holes, and hope no one notices.