Hashcash
Sign in to saveHashcash is a proof-of-work system used to limit email spam and denial-of-service attacks. Hashcash was proposed in 1997 by Adam Back and described more formally in Back's 2002 paper "Hashcash – A Denial of Service Counter-Measure". In Hashcash the client has to concatenate a random number with a string several times and hash this new string. It then has to do so over and over until a hash beginning with a certain number of zeros is found.
Wikidata facts
- Instance of
- software
- Official website
- hashcash.org
Show 3 more facts
- inception
- 1997-00-00
- discoverer or inventor
- Adam Back
- uses
- proof of work
Sources (3)
via Wikidata · CC0
~13 min read
Encyclopedic overview
19 sectionsContents
- Background
- How it works
- Technical details
- Sender's side
- Recipient's side
- Required effort
- Advantages and disadvantages
- Applications
- Bitcoin mining
- Spam filters
- Email clients
- Email Postmark
- Blogs
- Reputation
- Intellectual property
- See also
- Notes
- References
- External links
Hashcash is a proof-of-work system used to limit email spam and denial-of-service attacks. Hashcash was proposed in 1997 by Adam Back and described more formally in Back's 2002 paper "Hashcash – A Denial of Service Counter-Measure". In Hashcash the client has to concatenate a random number with a string several times and hash this new string. It then has to do so over and over until a hash beginning with a certain number of zeros is found.
==Background== The idea "...to require a user to compute a moderately hard, but not intractable function..." was proposed by Cynthia Dwork and Moni Naor in their 1992 paper "Pricing via Processing or Combatting Junk Mail".
Excerpted from Wikipedia’s “Hashcash” article, available under the CC BY-SA 4.0 licence.