Hashcash - A Denial of Service Counter-MeasureBy Feb 26, 2019 1 Min Read
Adam Back created Hashcash in 1997 to prevent denial-of-service attacks and reduce junk mail. It outlines the proof of work, similar to the one used by Bitcoin, which uses a cryptographic hash function requiring users to compute a problem of a pre-defined level of difficulty before a certain action can occur. For normal email users, this processing would require negligible computing costs and would not have a significant impact to performance. However, this would serve to prevent malicious parties from sending mass emails by increasing the processing power required, and therefore making it substantially more costly to perform such an action. This would later be the inspiration to Bitcoin's own proof of work consensus protocol that mainly serves to govern the legitimacy of transactions and reward participants for their validation work.
Excerpt from Hashcash
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