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
- Official website
- hashcash.org
Show 1 more fact
- inception
- 1997-00-00
Sources (3)
via Wikidata · CC0
~13 min read
Article
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".