Re: Anonymous digital cash, on top of bitcoin

80 bytes for the "bonus storage," not just the standard 80 byte header. 

Per Gavin:
So, with some reluctance, I recently mergedpull request #2738 : “Relay OP_RETURN data TxOut as standard transaction type.”

The idea is to give people a way to do what they clearly want to do (associate extra data with a transaction that is secured by the blockchain), but do it in a responsible way that strikes a balance between “you can put whatever you want into the blockchain” and “you will have to be tricky and inefficient to get your data in the blockchain.”

Pull request #2738 lets developers associate up to 80 bytes of arbitrary data with their transactions by adding an extra “immediately prune-able” zero-valued output.

Why 80 bytes? Because we imagine that most uses will be to hash some larger data (perhaps a contract of some sort) and then embed the hash plus maybe a little bit of metadata into the output. But it is not large enough to do something silly like embed images or tweets.



From: https://bitcoinfoundation.org/blog/?p=290



> On Nov 11, 2013, at 9:06 PM, "Melvin Carvalho" <melvincarvalho@gmail.com> wrote:
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>> On 11 November 2013 14:12, Goss, Brian C., M.D. <Goss.Brian@mayo.edu> wrote:
>> 80 bytes (*essentially; otherwise it's a 5 page explanation); enough for a 64 byte hash and 16 byte UUID.
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> Each block header is part of a timestamp server which is currently 80 bytes in the reference serialization.  This should be pretty stable as the timetamp is an unsigned in which will only cycle round next century (2106?)
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> Ive pretty much modelled 70% of bitcoin using linked data, most importantly the block chain, but not yet transactions.  I should have this complete, and compatible with payswarm technology in the next 1-2 weeks... 
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>> Brian
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>> > On Oct 31, 2013, at 6:49 AM, "David Nicol" <davidnicol@gmail.com> wrote:
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>> > I see Bitcoin as primarily a ledger system. Since the bitcoin protocol allows additional data to be included in the registered transaction, one could layer anything requiring a permanent record on top of it. Transaction fees (in BTC) would be the only BTC requirement. After, of course, figuring out the details of shoehorning whatever you are wanting to record into the available space.
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