Interpol FUD (Images in the blockchain?)

Posted by on Jun 4, 2015 in Reviews, Thoughts | One Comment

I just received this article via email. http://www.interpol.int/News-and-media/News/2015/N2015-033.  Let’s have a look at this article.  First the article mentions the transactions are encrypted, but that is not the case.  Bitcoin transactions are displayed in plain text.

“The design of the blockchain means there is the possibility of malware being injected and permanently hosted with no methods currently available to wipe this data. This could affect ‘cyber hygiene’ as well as the sharing of child sexual abuse images where the blockchain could become a safe haven for hosting such data.”

While this *could* be done, it is simply not practical.  The only way to store arbitrary data in a bitcoin transaction, is to use the OP_RETURN field.  This is currently limited to 80bytes.  Lets say you want to store a 600 x 338 image, very small by todays standards, less than 1mp.  Even with compression, the file size is 66 kilobytes or 66,000 bytes!

66,000 / 80 = 875 transactions required to send an image.  Also as bitcoin transactions are unordered, that payload would need to include some identifier to re-order the “image”.

At around 1 cent per transaction, it would cost $8 to send.  You would be better off sending via SMS or Twitter, at least the later is free and can hold 160bytes!

  • thirdalbum

    The malware bit is totally ridiculous. The child porn images is once again beating on the “think of the children” drum but as you note it can certainly be done. However, free transactions can be used for this and there is software already available to place files into OP_RETURN transactions without you having to sort it out yourself.