But, would this leave a loophole for text-only and/or highly bandwidth-limited communications to remain end-to-end encrypted?
If you cannot sent a photo, audio or video, kind of hard to send CSAM material, yet end-to-end real-time SMS type messages are still somewhat useful in many instances (better than nothing).
Anyone with more detailed info?
What is your argument - that "think of the children" therefore ban all end-end encryption? If so, then any form of encryption should be absolutely banned. So should carrier pigeons, as they are very hard to intercept, and a leg band could carry a chip w/gigabytes of CSAM images.
My point is that in within a regime of highly restricted encryption (for the purposes of CSAM prevention), there should be space for a text-based conversational system that is very useful for text comms, but highly impractical for CSAM.
Limiting it to 30KB/day of transmission leaves plenty of room for useful conversational communication. That's ~45min of world-record typist speed on a full keyboard (17char/sec), or about 10 pages of single-spaced text -- a more than adequate secure conversations channel.
Yet transmitting a single 1MB image in Base64 encoding would take 45 days. One could literally be 2x faster by carrying it on a bicycle from Los Angeles to NYC.
The point is that this remains a pragmatically useful solution.
While it could technically be used to transmit images by parallelizing it, etc., the goal is to make it bad enough for those purposes that practically, other solutions are better.
By creating a really bad channel for images, many other solutions become pragmatically better (e.g., snail mail & encrypted USB drive, carrier pigeon, etc), even though it remains mathematically possible to use this.
The analogy is a common home front door lock set. They are good enough to prevent casual break-ins, but can cracked in minutes by a professional burglar. The lock does not need to be perfect, only good enough that it becomes pragmatically easier to break in by other routes (e.g., crack a window, etc.)
The question is, what is your solution? Ban this too because it is mathematically imperfect -- i.e., ban all encryption -- or what else?