Quote from: LoyceV on April 04, 2022, 07:38:32 AM

Using a third-party website to verify a signed message is terrible for privacy, but the site might work offline. I haven't been able to test that, because I haven't been able to verify the LoG. All I get is:

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Signature Verification Failed

I'll continue my review here. The delay is caused by me (Support Chat answered after 2 hours, I took 3 days to continue my testing):
Me:

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Can you walk me through verifying the LoG on 8gwifi.org, or any external tool? I still can not figure it out.

Support Chat:

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Of course! So first, visit the site https://8gwifi.org/rsasignverifyfunctions.jsp. After that, select Verify Signature option first.
Public Key: Enter the public key in the LoG including -----BEGIN PUBLIC KEY----- and -----END PUBLIC KEY-----
ClearText Message: Enter the content of SIGNATURE FORMAT in the letter of guarantee, but without memberCode and so on. Only the content that comes one line after with your real member code and so on.
Provide Signature Value: Enter the content of the signature in the Letter of Guarantee. Here without -----BEGIN SIGNATURE----- and -----END SIGNATURE-----
You will also need to choose SHA256withRSA in the RSA Signature Algorithms below
Then it will show that the signature verification is passed

This verified the signed message. It might be good to add verification instructions to the website.
But 8gwifi.org's verification didn't work offline, so chances are the 8gwifi.org server now knows the details of my transaction.
After I verified the LoG, I made a deposit. I used a short delay to speed things up.

When I checked my wallet after a while, it had 11 confirmations already. But the site (on Tor browser) still shows an animation and this:

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Awaiting Confirmations
0.00xxxxxx BTC 0 / 2 Confirmations

If this can be fixed to auto-update, that would be great. I thought fees must have gone up, so I was still waiting until I checked my own wallet.
Reloading the page fixed it.

After reaching Step 5 ("Done!"), I can't check back the earlier steps anymore for the exact details, but at Step 4 it showed that I would receive a slightly larger amount than what I actually received. The difference wasn't much (maybe 1000 sats), but this should have been the exact amount. The total fee is now about 50% higher than what it showed earlier.

Suggestion: can you make the random fee provably fair? For instance, you can use the order ID and block hash of the incoming transaction as input to generate the random number. This might prevent complaints if someone is charged 3% on a large deposit. This can be prevented if both you and the user can't know fee before the deposit gets confirmed.

Coinjoin?
Now the thing it's all about: a coinjoin transaction! The transaction I received had 1 input and 2 outputs.
Let me quote from the website:

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CoinJoin is a method where different people join together a single pool and together create a single transaction where each of them give coins as inputs and fresh & anonymous addresses as outputs.

This didn't happen. I expected my own deposit to join a pool of other transactions, and be included in the transaction that funds my withdrawal address.

I followed my withdrawal up the blockchain, until I got to March 29, 2022. This is the first transaction that looks like a coinjoin. But if I follow it a bit further, I get to many parent transactions that look the same, which makes me think the same funds are being used for several coinjoins in a row. This one is from February 10, 2022 for instance.

The entire concept of "UniCode" doesn't make sense when doing a real coinjoin:

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With this UniCode we make sure that the same coins are not sent again to the same user in future mixing operations.

With coinjoin, I expect to receive part of my own coins back. What you're doing now is what most "classic" mixers do.

Quote from: LoyceV on March 30, 2022, 07:17:43 PM

From Terms and Conditions:

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The service is provided on a non-custodial basis.
~
trustless CoinJoin

I'll get back to this later.

To conclude: it's not non-custodial, it's not trustless, and it's not coinjoin. I've said this before in a discussion with another mixer: you're in the business of trust. People need to be able to absolutely trust you're going to do what you say you're going to do. Now it looks like you're using buzzwords to inspire confidence. All in all this does the opposite: if you lie about things that I know for sure are incorrect, how can I trust you on other promises, such as not keeping any logs?

One more thing: Support Chat rejects many normal characters, I can't say "can't" and I can't use (brackets). If that can be fixed, that would be great! It's annoying having to remove common characters for every message I post.

This completes my review. Sorry for doing it in several parts, but it was necessary to verify things before I could continue with confidence.