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fidelity.link

A pseudonymous anti-spam identity system based on the blockchain.

Concept and idea based previous work by Peter Todd, Jeff Garzik and others.

Overview

A fidelity bond for the purposes of this app is a certain amount of bitcoin days that are sacrificed to the miners or whoever gets to redeem a transaction.

The value of the fidelity bond is the amount of satoshis being sacrificed.

In order to certify that the bitcoins can be redeemed by anyone, an output of a transaction is locked with OP_CHECKLOCKTIMEVERIFY, and the redeem script is revealed in the same transaction with an OP_RETURN. P2SH is needed due to the use of a non-standard script.

At least 2015 blocks must be mined between the block that includes the fidelity bond transaction and the block redeeming it. OP_CHECKSEQUENCEVERIFY is more suited than OP_CLTV for this, but hasn't been deployed yet.

The redeem script structure is: <magic string> <block height> OP_CHECKLOCKTIMEVERIFY OP_DROP