Yet Another Final Ultimate Solution to the Spam Problemtm
Microsoft is proposing yet another solution to the spam problem. They call it Penny Black. The proposal is similar to various e-postage proposals (in which the sender is required to bundle a small amount of e-cash in the header of the email; the recipient can choose to refund the e-cash to friends and other non-spammers, while spammers wind up spending real money on each message they send.)
In the Microsoft proposal, the sender's expenditure is measured in cpu cycles instead of money. When a recipient does not trust the sender, it sends the sender a computationally-expensive puzzle to solve (typically breaking a one-way hash). If there are 86,000 seconds in a day, and the puzzle takes ten cpu-seconds to solve, a spammer would be limited to sending 8600 spams per day.
The idea is actually not original to Microsoft; see the Hashcash web page and corresponding Wikipedia entry.
Excersize for the reader: find two things wrong with this proposal. See the FUSSP web page for hints.
In the Microsoft proposal, the sender's expenditure is measured in cpu cycles instead of money. When a recipient does not trust the sender, it sends the sender a computationally-expensive puzzle to solve (typically breaking a one-way hash). If there are 86,000 seconds in a day, and the puzzle takes ten cpu-seconds to solve, a spammer would be limited to sending 8600 spams per day.
The idea is actually not original to Microsoft; see the Hashcash web page and corresponding Wikipedia entry.
Excersize for the reader: find two things wrong with this proposal. See the FUSSP web page for hints.
3:29 PM |
permalink
1 Comments:
Penny Black has been around forever. Microsoft got all excited about it a few years ago when they hired Cynthia Dwork away from IBM. When I talked to her about it at the CEAS conference a few years ago, she agreed that zombie farms completely defeat any sort of hashcash, since the bad guys have more computing resources than the good guys.
Post a Comment
<< Home