content: This is true, however it's an alarmist call and can be ignored for the most part. Quantum computer can quickly brute force encryption algorithms created for older computers, the same way computers could break older encryption standards as they got faster. It's why we keep increasing the key length for signing, it makes it harder for the key to be brute forced. Quantum encryption algorithms wont be easily beat by quantum computers, but they will break open all the old stuff pretty easily.