20. "Proof-of-Work" Tokens and Spammers

20

“Proof-of-Work” Tokens and Spammers

HERE IS AN INTERESTING CONVERSATION between Hal Finney, a well-known developer in the cryptography industry, and Satoshi Nakamoto that focuses on how Bitcoin’s proof-of-work could be used to limit spammers or to reward spam recipients. Hal Finney is credited with creating the first “reusable proof-of-work system”, a variant of Bitcoin’s proof-of-work that is not necessary to be understood for this topic to be comprehensible. Also Hal Finney is the recipient of the first Bitcoin transaction, whose sender was Satoshi himself.

Re: Bitcoin v0.1 released

Satoshi Nakamoto Sun, 25 Jan 2009 08:34:340800

Hal Finney wrote:

* Spammer botnets could burn through pay-per-send email filters trivially

If POW tokens do become useful, and especially if they become money, machines will no longer sit idle. Users will expect their computers to be earning them money (assuming the reward is greater than the cost to operate). A computer whose earnings are being stolen by a botnet will be more noticeable to its owner than is the case today, hence we might expect that in that world, users will work harder to maintain their computers and clean them of botnet infestations.

Another factor that would mitigate spam if POW tokens have value: there would be a profit motive for people to set up massive quantities of fake e-mail accounts to harvest POW tokens from spam. They’d essentially be reverse-spamming the spammers with automated mailboxes that collect their POW and don’t read the message. The ratio of fake mailboxes to real people could become too high for spam to be cost effective.

The process has the potential to establish the POW token’s value in the first place, since spammers that don’t have a botnet could buy tokens from harvesters. While the buying back would temporarilylet more spam through, it would only hasten the self-defeating cycle leading to too many harvesters exploiting the spammers.

Interestingly, one of the e-gold systems already has a form of spam called “dusting”. Spammers send a tiny amount of gold dust in order to put a spam message in the transaction’s comment field. If the system let users configure the minimum payment they’re willing to receive, or at least the minimum that can have a message with it, users could set how much they’re willing to get paid to receive spam.

Satoshi Nakamoto

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