If we're talking about smart contracts and such (which we are) then there's no text to search from contracts and such. The digital contract functionality doesn't work like Blockchain.info comments.
If you're going to use the Blockchain to lodge a patent for example, you're not uploading the actual patent. A hash is being made of the time (ie perhaps the hash of block at that height) and a hash of the document, which is then concatenated and then hashed again. So at it's simplest it's:
hash( hash(Blockchain time data) + hash(Document))
Think of it like this: the patent is in an envelope. The envelope is sealed with wax and stamped with a stamp referencing:
- proof of time and
- proof of envelope's contents
The text inside the envelope isn't searchable, whilst Blockchain.info comments (analogous to post-it notes in an accounting ledger) might be, though the usefulness is not the same.
2It isn't true that every transaction contains 80 bytes of text; this is an optional feature and used only occasionally. If you are running a full node such as Bitcoin Core, you could simply grep the block files; then the harder part is identifying the start and end of the transaction and computing its id. – Nate Eldredge – 2014-09-01T19:29:12.350
1There are several methods of sending text in bitcoin transactions. It is not nescessarily 80 characters. One method most often used, is to have a multisig transaction, where some of the publickeys contain the text, instead of being a valid public key. – Willem Hengeveld – 2014-09-05T07:37:55.103
Would it be useful to make a search engine for all of this? Maybe I should do that – Zubair – 2014-09-05T08:24:26.580
It is possible to make search engine. But i doubt that it would be useful for something. – amaclin – 2014-09-08T11:31:20.920
What about for searching through all those Digital Contract type uses of the Blockchain? I would have thought that was the killer app for Bitcoin? – Zubair – 2014-09-08T11:46:47.947
Thanks, that makes alot of sense. So where will the actual data be stored if only the hash is stored on the BlockChain? – Zubair – 2014-09-09T12:25:30.870
@AussieCryptocurrency. Add that comment as an answer and I will accept it and award the bounty, as I assume you have got the closest and most correct answer, even if what I wanted to do by searching the blockchain is not possible – Zubair – 2014-09-09T12:26:43.280