Finding the images is basically a treasure hunt. I look through the blockchain for things that look like they might be images. Strings ending in '.jpg' are a big clue. Or strings such as JFIF that appear inside jpg images.
Once I've found a potential location, I either parse the transactions myself with a Python script or pull up the raw data in blockchain.info or blockexplorer.com. Then I need to extract the image file from the raw data. People use a variety of ways of encoding the data, which makes it tricky. For example, the logo image was in the Usenet yEnc encoding. Hopefully the result of this process is a viewable image.
TL;DR: look at a whole lot of hex data until you find an image
Eventually someone is going to make a program to store and retrieve child porn directly in the blockchain. That way it can be passed around and stored on hard disks but with thin deniability of "oh no, I just needed the blockchain so I could spend my buttcorns"
>**Bitmessage** is a [decentralized](http://en.wikipedia.org/wiki/Decentralized), [encrypted](http://en.wikipedia.org/wiki/Encryption), [peer-to-peer](http://en.wikipedia.org/wiki/Peer-to-peer), trustless communications protocol that can be used by one person to send encrypted messages to another person, or to multiple subscribers. Bitmessage encrypts each users' message inbox using [strong encryption](http://en.wikipedia.org/wiki/Public-key_cryptography) and replicates it inside its [P2P](http://en.wikipedia.org/wiki/Anonymous_P2P) [network mixing](http://en.wikipedia.org/wiki/Mix_network) it with inboxes of other users in order to conceal user's identity, prevent eavesdropping and protect the network from any control. The Bitmessage [communication protocol](http://en.wikipedia.org/wiki/Communications_protocol) avoids sender-spoofing through strong [authentication](http://en.wikipedia.org/wiki/Authentication), and hides [metadata](http://en.wikipedia.org/wiki/Metadata) from wiretapping systems.
^Interesting: [^Anonymous ^P2P](http://en.wikipedia.org/wiki/Anonymous_P2P) ^| [^Tor ^\(anonymity ^network)](http://en.wikipedia.org/wiki/Tor_\(anonymity_network\)) ^| [^Namecoin](http://en.wikipedia.org/wiki/Namecoin) ^| [^Silent ^Circle ^\(software)](http://en.wikipedia.org/wiki/Silent_Circle_\(software\))
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A map to find treasure or secret passwords or the end of the world plans...Just imagine what could end up in the blockchain. Part time capsule part safe part invisible ink part James bond part infinity. Just think of all the craziness..I need to put something in the blockchain. But what...
Putting a 20 character message in the blockchain is trivial - the steps are in the article. Doubledogs: send a few cents to 1849mWf4uQbArUBGGh63cGrm2QYbkgFFLu and you'll have your marriage proposal. And vincentbelkin: send to 1Bo738DkRgHK53QxFVaegkQUbXGrNNdHVo to get yourself immortalized. (Remember, anything going to these addresses is lost forever into the Bitcoin void, so don't send more than a trivial amount.)
If you send bitcoins to the address above (which nobody has yet), the transaction is recorded in the blockchain. The address is stored in the blockchain as a "Hash 160" in hex. For example, 1849mW... is stored in the blockchain as 20 hex bytes 4d6172... However, the byte 4d is 'M' in ASCII. The byte 61 is 'a' in ASCII, 72 is 'r', and so on. So if you look in the blockchain for ASCII strings (bitcoinstrings.com is the easy way), you would see the hidden text message.
Maybe I should write an article about this :-)
this is funny. because i dont understand any of this.
cool how theres theres technical guys like you, you are the mechanics and engineers of bitcoin. and guys like me are just the car salesmen of bitcoin. http://redd.it/1ucn47/ <-- thats about the limit of my understanding of bitcoin.
I checked five different encodings and the 09 F9 key isn't in the blockchain, which surprised me a bit.
And, for those who didn't read the article, images can be embedded in the blockchain fairly easily and there are a bunch of JPGs and PNGs in there already, including Nelson Mandela, the Bitcoin logo, and assorted photos.
There is nothing illegal that you can put in the blockchain. There were some kiddy porn links put in already, but the contents of the website are illegal, not the sole urls. You cannot "inject" a whole jpeg for instance. No worry then.
Go ahead and try to explain the technical difference of "there's a link to the contents of a website that contains kiddy porn in the bitcoin blockchain" and "bitcoin supports kiddy porn" once the media gets ahold of it.
Sure, simply base64 encode an image, and split it up into the right sized chunks. Convert those chunks into addresses.
Thus, there is an image in the blockchain itself. (This causes a loss of those bitcoins)