People usually encrypt messages on Bitcoin blockchain through a sent transaction. These messages varies from different individual and organisation records. The first message recorded on Bitcoin blockchain network was in 2009. It was encrypted in the bitcoin blockchain’s genesis block.
Recently a certain biblical message was seen encrypted in a transaction in block number 666,666 of the Bitcoin (BTC) blockchain. The message is a quotation from the sixth book in the New Testament, St.Paul’s epistle to the Romans. It reads:
“Do not be overcome by evil, but overcome evil with good – Romans 12:21.”
The individual who sent the transaction paid over $50 in fees. This is quite expensive compared to the normal peak average fee on Bitcoin blockchain in a day via bitinfocharts.com records. This shows that the sender’s interest was to have the transaction, and the message, imbedded in block 666,666.
Why pay such a high fee just to save a message on the blockchain?



Hey Newbies (& Jr Members)! I want to give you the opportunity to earn some merit by using your Bitcoin client (or whatever you use). There is a great guide linked below showing you how to sign a message.
https://bitcointalk.org/index.php?topic=990345.0.
Just in case you are wondering how to send an encrypted message. Here's a thread by OgNasty.