1/ Thread on comparing “reasonably private” spends in #Monero and #Bitcoin , and trying to find a better way to judge scalability/throughput if all spends provide reasonable/good privacy guarantees.

Starting off with transaction sizes, or more accurately, “private spend size”:

2/ I dove into Samourai’s Whirlpool for stats on the Bitcoin side, as they are the de facto privacy implementation for Bitcoin ATM.

Normal "reasonably private spend" TX in Bitcoin: 2,363b, 1,475vb
Normal "reasonably private spend" TX in Monero: 1,700b

3/ I got this data by digging a bit for a “normal” tx0->Whirlpool->STOWAWAY spend, as that is generally regarded as the “proper” way to spend Bitcoin privately. Here are the TX links used:

https://blockstream.info/tx/5787a5eb16bb7e5e16651f5f1bdc5afde146c6f7f5b3516e1ab77c5444128fa2?output:5
https://blockstream.info/tx/4e72519d391ce83e0659c9022a00344bedbb253de1747cf290162b3d3ea51479
https://blockstream.info/tx/ce2394b8d4d3b5be4712184b554c8b8ca6772e5baa1123482b9e50ef5bf2e8a2?input:0

4/ Note that the above is not necessarily a linked spend, but merely a tx0/mix/STOWAWAY spend from the same mix instance, so is a good estimate.

I also verified those numbers with several others and was told they’re within the expected range.

5/ That means that for “comparable” (these things are hard to compare, naturally) privacy in Bitcoin and Monero, Bitcoin spends take up ~600b *more* per spend than Monero, and are more difficult to accomplish for the end user.

6/ Now on to costs. This is much more subjective as Bitcoin obviously sees far more on-chain activity:

Normal "reasonably private spend" TX in Bitcoin (excluding "doxxic" change): 0.136USD @ 1sat/vb
Normal "reasonably private spend" TX in Monero: 0.0018USD (median as of 07/20)

7/ That means that at the absolute cheapest, the private spend costs ~100x more than the Monero spend, for similar privacy guarantees.

This will likely change some, especially as USD prices for both fluctuate, but is good to include in the comparison.

F/ I was absolutely not expecting this conclusion, and am hopeful to hear more input (and even be shown to be wrong) down the line!

I don’t think this type of comparison has been done before, but I think its a valuable comparison to have!