On January 29, data analyst James Waugh decided to test and see if the Cashfusion protocol was really anonymous. After testing Cashfusion, Waugh explained he sifted through a number of transaction inputs and outputs and realized that it’s “not possible to establish a concrete link” between them.
This week Bitcoin Cash supporters were pleased to see that Cashfusion passed rigorous testing when data analyst James Waugh decided to comb through a slew of Cashfusion transaction inputs and outputs. Following the experimentation, Waugh wrote a blog post on Medium called “Is Cashfusion Really Anonymous?”
“A newer Coinjoin protocol called Cashfusion doesn’t enforce the requirement of equal payment amounts and instead purports anonymity due to the high number of participants in a transaction”, Waugh said.
The data analyst decided to see if the Cashfusion developers’ claims were true. He added:
Some individuals in the cryptocurrency community are skeptical of these claims. I set out to try to crack Cashfusion by linking inputs and outputs together and then proving that they had to be the true transaction.
Cashfusion is an extension of the Cashshuffle mixing application that launched last year and the protocol improves upon Cashshuffle by allowing people to fuse coins without the requirement of equal payment amounts. Cashfusion is getting lots of attention from BCH users. The privacy enhancing protocol was cast into the limelight even more so after the Wasabi wallet creator complimented the concept.
Bitcoin Magazine’s technical writer Aaron van Wirdum wrote an editorial about the subject as well. When Waugh tested Cashfusion, he leveraged an integer programming solver to try and find some matches. “After repeating this process for all the inputs and outputs in the original candidate match above, we find that there is no way for us to know if the candidate match we found is the true transaction”, the analyst stressed.
Waugh added:
It’s not possible to establish a concrete link between these inputs and outputs since it’s more likely that these inputs outputs are linked by pure coincidence than it is that they are verifiably linked by their payment amounts.
A candidate matched set of transaction inputs and outputs shown in Waugh’s Cashfusion review.
An Indication That the Cashfusion Developers’ Claims Are True
Waugh then asked himself if other matched subsets can be verified as the true payments and explained the answer is “no.” “I have repeated this process across thousands of matched subsets, none can be mathematically proven to be the true transactions”, Waugh remarked. “So to sum up (excuse the pun), we have somewhat verified the Cashfusion’s developers’ claims that even if someone could link inputs and outputs such that they balance, due to the high number of inputs and outputs it’s impossible to determine the true way that inputs and outputs truly relate (since there are multiple possible combinations of ways of getting the inputs and outputs to balance)”, Waugh concluded.
Imagine dedicating a lot of effort to break #CashFusion and then remember that, with #Schnorr signatures, you can have multiple parties involved in each input.
If #CashFusion gains traction that’s a possibility that cannot be ignored.
— Cláudio Gil (@m4ktub2) January 30, 2020
The analyst further stated that the testing results were “encouraging for Cashfusion users” and emphasized that “Cashfusion is far more practical than other Coinjoin protocols that require users to send equal transaction amounts.” The news follows the recent 5th Anti-Money Laundering Directive (AMLD5) and FATF guidelines that are being enforced this year throughout the U.S. and across Europe.
Because of the regulatory climate, cryptocurrency exchanges in these regions have ramped up identification and KYC processes. Moreover, the testing results also follow the recent Paxos Global customer ‘Ronaldmchodled’ tweeting about the exchange giving him issues because they thought he was sending to a mixing service. Despite exchanges like Binance and Paxos discouraging crypto mixing, protocols like Cashfusion are improving crypto privacy a great deal.
