Could the bitcoin protocol be used to defeat logins and passwords of websites?
closed as unclear what you're asking by Nate Eldredge, Pieter Wuille, Murch♦, Salvador Dali, Stéphane Gimenez Jan 21 '14 at 12:58
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The website could give you a random string that you would use to sign a symbolical transaction to the blockchain. Once the transaction is done, the website can assign your bitcoin address with that initial random string and allow you to log into their site.
In fact it could replace systems like OpenID where you'd just make a single symbolical transactions that various other sites would understand and can log you in.