How will the range proof size reduction be accomplished?

Question

According to this answer

Range proofs are currently 6304 bytes (per output) and will drop in the future by at least 1024 bytes.

1. How will the future 1024 byte reduction per output be accomplished?
2. Assuming proper implementation will there be any security or privacy concessions associated with that byte size reduction?

Answer 1

This is a bit speculative, as I do not know exactly what is planned.

1024+ bytes is quite a reduction, so my guess is that the range will be reduced. Currently the spender must prove the output is in the range [0, 2^64), and if the upper limit were reduced it would reduce the size of the signature. This would not alter security, but would decrease the amount that could be sent in a single output. Amounts larger than the upper range could still be sent to a single address in one transaction, but would require multiple outputs to do so.