Samourai vs Wasabi Mixing Architecture

You have 3.5BTC that you want to mix with either Whirlpool or with Wasabi. For the sake of comparison, I assume 1BTC base denominations are used in both schemes. Let’s examine how the two mixers perform side by side.

With Whirlpool, first you make a tx0, which results in 1,1,1,0.5 , then you make 3 more mixes on the 1BTC outputs. You’ll end up with 1,1,1,0.5.

With Wasabi your first mixing transaction will result in 1,2,0.5 and your next mix will result in 1,1,1,0.5. Notice one of the 1BTC is a change there, so the Wasabi user would do one more mix on it: 1,1,1,0.5 .

Blockspace Usage

Whirlpool did 4, Wasabi did 3 transactions, but what really matters for calculating how much space you used up from the Blockchain and ultimately how much network fees you will play is the number of transaction outputs created during the process.

Whirlpool created 4+3 outputs. 4 in tx0 and 3 in the consequent mixes.
Wasabi created 3+3 outputs. 3 in the first mix and 2 in the next one.

7 vs 6 outputs to achieve the same result, right? Not entirely. Wasabi mixes are also gaining more anonymity.

Anonymity Gained

Let’s assume 10 anonset for 1BTC denomination both in Whirlpool and in Wasabi and 2 anonset for 2BTC denomination in Wasabi.

Whirlpool.

1. tx0: doesn’t add any anonymity.
2. mix1,2,3: All the 1BTC coins reach 10 anonymity and the 0.5BTC coin reaches nothing.

Wasabi.

1. mix1: 1BTC coin reaches 10 anonset, 2BTC coin reaches 2 anonset, 0.5BTC reaches nothing.
2. mix2: 1BTC coin reaches 10 anonset.
3. mix3: 1BTC coin reaches 10 anonset.

So Whirlpool ends up with 1(10), 1(10), 1(10), 0.5 (1) and Wasabi ends up with 1(10), 1(2*10), 1(2*10) 0.5(1) .

What about remixes?

What about them? Further remixes of 1BTC coins in any of these schemes result in the same blockspace usage and anonymity gains. (Of course, if we dismiss the fact that you gain zero anonymity against Samourai, the company itself, due to exposing extpubkeys in the first place.)

Why Would You Do That?

Whirlpool was based on my ZeroLink research and this was known even back then. This begs for the question:
If Whirlpool uses more block space and provides less anonymity why did Samourai decide to make their product intentionally inferior to Wasabi? The answer is:

MARKETING

Samourai also created a block explorer, KYCP used to spread their propaganda, where they depict their transactions like this:

While Wasabi transactions like this:

And everyone knows green is better than yellow!

Another interesting note is they show the mixes for Whirlpool transactions, but for Wasabi transactions they for some reason decided to not show them, they only show the non-mixed changes, but that’s another topic on dishonesty.

Conclusion

Samourai Wallet is known for cutting corners, but intentionally designing and implementing a less efficient system for the sake of marketing is another low.