16 ms·

If you wanted to keep it safe from spam, you'd use a proof-of-work scheme using a memory-hard hash function like scrypt, or a Captcha, or an invite-code system

by kragen 10mo ago

If you wanted to keep it safe from spam, you'd use a proof-of-work scheme using a memory-hard hash function like scrypt, or a Captcha, or an invite-code system like lobste.rs or early Gmail. Signal's architects already knew that when they started designng it.

codedokode 10mo ago
Or a small payment in cryptocurrency.
- kragen 10mo ago
  Yes, that would also work, but you should probably offer alternatives.
creata 10mo ago
> you'd use a proof-of-work scheme I thought the general belief (e.g., '“Proof-of-Work” Proves Not to Work') was that proof-of-work isn't very good anti-spam. > or a Captcha Aren't bots better at those than humans by now? And making people do captchas in an instant messenger is a great way to make people not use that instant messenger. > or an invite-code system like lobste.rs or early Gmail. That's not a long-term option if you want to make something mainstream.
- kragen 10mo ago
  There are people who believe that proof-of-work isn't very effective, but none of them have succeeded in spamming the Bitcoin network with blocks they've mined, driving the other miners out of business, nor (for the last several years) with spamming the Bitcoin network with dust transactions they've signed, so I don't think we should take their opinions very seriously. Bots may be better than humans at Captchas now, although I'm not certain of that, but they certainly weren't when Signal was designed. I don't see why invite codes would be a problem for mainstream use.
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  - Ieghaehia9 10mo ago
    > There are people who believe that proof-of-work isn't very effective, but none of them have succeeded in spamming the Bitcoin network with blocks they've mined, driving the other miners out of business, nor (for the last several years) with spamming the Bitcoin network with dust transactions they've signed, so I don't think we should take their opinions very seriously. Different system. The parent and GP are talking about proof-of-work being used directly for account creation. If a chat service required mining-levels of PoW (and hence any prospective new users to have an ASIC), it would not be very popular. Nor would it be very popular if it used a relative difficulty system and the spammers used dedicated servers while the legitimate users had to compete using only their phones.
  - creata 10mo ago
    > none of them have succeeded in spamming the Bitcoin network with blocks they've mined I'm not saying you're wrong, but I have no idea what you're getting at, because the sentence sounds kind of absurd. As a result, I'm not sure if it addresses your point, but just to throw it out there: Bitcoin and anti-spam are different applications of proof of work. Anti-spam has to strike a compromise between being cheap for the user (who is often on relatively low-powered mobile hardware), and yet annoying enough to deter the spammer. It's not unreasonable to believe that such a compromise does not exist. > Bots may be better than humans at Captchas now, although I'm not certain of that, but they certainly weren't when Signal was designed. Fair point, but again, even in 2014, an instant messenger with captchas would have much more friction than every other messenger. And captchas aren't just bad because they introduce enough friction to drive away pretty much everybody: they also make users feel like they're being treated as potential criminals. > I don't see why invite codes would be a problem for mainstream use. Can you elaborate? Invite codes blocking access to the service itself "like lobste.rs" mean that no one can use your service unless they've been transitively blessed by you. That's obviously going to limit its reach...
- alkindiffie 10mo ago
  > That's not a long-term option if you want to make something mainstream. Groups in messaging apps rarely contain more than 100 users. So invite codes can work well for messaging apps.
maqp 10mo ago
>proof-of-work scheme using a memory-hard hash function like scrypt So who's doing the computation? The spammer can't afford to run 3 second key derivation time per spam device? Or how long do you think normal user will wait while you burn their battery power before saying "Screw it, I'll just use WA"? Or is this something the server should be doing? >Captcha LLMs are getting quite good at getting around captchas. >invite-code system That works in lobste.rs when everyone can talk together, and recruit interesting people to join the public conversation. Try doing that with limited invites to recruit your peers to build a useful local network of peers and relatives. "I'm sorry Adam, I'm out of invites can you invite my mom's step-cousin, my mom needs to talk to them?" >Signal's architects already knew that when they started designng it. I think they really did, and they did what the industry had already established as the best practice for a hard problem. The only reasonable alternative would've been email with heavy temp-mail hardening, or looking into the opposite end of Zooko's triangle and having long, random, hard-to-enumerate usernames like Cwtch and other Tor-based messengers do. But even that's not removing the spam-list problem of any publicly listed address ending up in a list that gets spammed with contact requests or opening messages with spam.
- kragen 10mo ago
  Those are reasonable questions, but they suggest that you don't understand the landscape very well. The user's device has to do the computation for it to be effective. How long does it normally take to sign up for a new messaging service like WhatsApp? Five minutes? You should burn the user's cellphone battery for about half that long, 150 seconds, 50 times more than you were thinking. Plus another half-minute every time you add a new contact. Times two for every time someone blocks you, up to a limit of 150 seconds. Minus one second for each day you've been signed up. Or something like that. The value of signing up for Signal is much higher to a real user than it is to a spammer, so you just have to put the signup cost somewhere in the wide range in between. LLMs didn't exist when Signal was designed, and Captchas still seem to be getting a lot of use today. Invite codes worked fine for Gmail, and would work even better for any kind of closed messaging system like Signal; people who don't know any users of a particular messaging system almost never try to use it. The diameter of the world's social graph is maybe ten or twelve, so invite codes can cover the world's social graph with only small, transitory "out of invites" problems. The "industry" had "established" that they "should" gather as much PII as possible in order to sell ads and get investments from In-Q-Tel.
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by kragen 10mo ago

codedokode 10mo ago

Or a small payment in cryptocurrency.

kragen 10mo ago
Yes, that would also work, but you should probably offer alternatives.

creata 10mo ago

> you'd use a proof-of-work scheme I thought the general belief (e.g., '“Proof-of-Work” Proves Not to Work') was that proof-of-work isn't very good anti-spam. > or a Captcha Aren't bots better at those than humans by now? And making people do captchas in an instant messenger is a great way to make people not use that instant messenger. > or an invite-code system like lobste.rs or early Gmail. That's not a long-term option if you want to make something mainstream.

kragen 10mo ago
There are people who believe that proof-of-work isn't very effective, but none of them have succeeded in spamming the Bitcoin network with blocks they've mined, driving the other miners out of business, nor (for the last several years) with spamming the Bitcoin network with dust transactions they've signed, so I don't think we should take their opinions very seriously. Bots may be better than humans at Captchas now, although I'm not certain of that, but they certainly weren't when Signal was designed. I don't see why invite codes would be a problem for mainstream use.
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- Ieghaehia9 10mo ago
  > There are people who believe that proof-of-work isn't very effective, but none of them have succeeded in spamming the Bitcoin network with blocks they've mined, driving the other miners out of business, nor (for the last several years) with spamming the Bitcoin network with dust transactions they've signed, so I don't think we should take their opinions very seriously. Different system. The parent and GP are talking about proof-of-work being used directly for account creation. If a chat service required mining-levels of PoW (and hence any prospective new users to have an ASIC), it would not be very popular. Nor would it be very popular if it used a relative difficulty system and the spammers used dedicated servers while the legitimate users had to compete using only their phones.
- creata 10mo ago
  > none of them have succeeded in spamming the Bitcoin network with blocks they've mined I'm not saying you're wrong, but I have no idea what you're getting at, because the sentence sounds kind of absurd. As a result, I'm not sure if it addresses your point, but just to throw it out there: Bitcoin and anti-spam are different applications of proof of work. Anti-spam has to strike a compromise between being cheap for the user (who is often on relatively low-powered mobile hardware), and yet annoying enough to deter the spammer. It's not unreasonable to believe that such a compromise does not exist. > Bots may be better than humans at Captchas now, although I'm not certain of that, but they certainly weren't when Signal was designed. Fair point, but again, even in 2014, an instant messenger with captchas would have much more friction than every other messenger. And captchas aren't just bad because they introduce enough friction to drive away pretty much everybody: they also make users feel like they're being treated as potential criminals. > I don't see why invite codes would be a problem for mainstream use. Can you elaborate? Invite codes blocking access to the service itself "like lobste.rs" mean that no one can use your service unless they've been transitively blessed by you. That's obviously going to limit its reach...
alkindiffie 10mo ago
> That's not a long-term option if you want to make something mainstream. Groups in messaging apps rarely contain more than 100 users. So invite codes can work well for messaging apps.

maqp 10mo ago

>proof-of-work scheme using a memory-hard hash function like scrypt So who's doing the computation? The spammer can't afford to run 3 second key derivation time per spam device? Or how long do you think normal user will wait while you burn their battery power before saying "Screw it, I'll just use WA"? Or is this something the server should be doing? >Captcha LLMs are getting quite good at getting around captchas. >invite-code system That works in lobste.rs when everyone can talk together, and recruit interesting people to join the public conversation. Try doing that with limited invites to recruit your peers to build a useful local network of peers and relatives. "I'm sorry Adam, I'm out of invites can you invite my mom's step-cousin, my mom needs to talk to them?" >Signal's architects already knew that when they started designng it. I think they really did, and they did what the industry had already established as the best practice for a hard problem. The only reasonable alternative would've been email with heavy temp-mail hardening, or looking into the opposite end of Zooko's triangle and having long, random, hard-to-enumerate usernames like Cwtch and other Tor-based messengers do. But even that's not removing the spam-list problem of any publicly listed address ending up in a list that gets spammed with contact requests or opening messages with spam.

kragen 10mo ago
Those are reasonable questions, but they suggest that you don't understand the landscape very well. The user's device has to do the computation for it to be effective. How long does it normally take to sign up for a new messaging service like WhatsApp? Five minutes? You should burn the user's cellphone battery for about half that long, 150 seconds, 50 times more than you were thinking. Plus another half-minute every time you add a new contact. Times two for every time someone blocks you, up to a limit of 150 seconds. Minus one second for each day you've been signed up. Or something like that. The value of signing up for Signal is much higher to a real user than it is to a spammer, so you just have to put the signup cost somewhere in the wide range in between. LLMs didn't exist when Signal was designed, and Captchas still seem to be getting a lot of use today. Invite codes worked fine for Gmail, and would work even better for any kind of closed messaging system like Signal; people who don't know any users of a particular messaging system almost never try to use it. The diameter of the world's social graph is maybe ten or twelve, so invite codes can cover the world's social graph with only small, transitory "out of invites" problems. The "industry" had "established" that they "should" gather as much PII as possible in order to sell ads and get investments from In-Q-Tel.

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