If I am not a miner and would like to put arbitrary data in the block chain, is there currently any method or protocol to get a miner to add it for me?

1 Answer 1


There is a service named btcmsg which allows you to do this. Here is the announcement in bitcointalk. The website is at btcmsg.staticloud.com.

They use a simple protocol to write and read the messages in the blockchain:

BTCmsg Protocol v1 (2011-09-18)

Each message is represented by multiple payment which is calculated by the following algorithm:

  1. Two first chars for message type ('01' for md5, '02' for ascii).
  2. Then the message in hex (python binascii.hexlify).
  3. Split the long string to groups of 4 hex digits.
  4. Each group of 4 hex (e.g. 2 ascii letters from the message) is represented by a payment in satoshi (maximum 0xffff=65535).
  5. The service fee (composed of a fixed part and a variable part times the amount of small payments required, minus the transaction fee) can be seen within the first transaction.

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