[cryptography] Is BitCoin a triple entry system?

Mon Jun 13 06:03:59 PDT 2011

On 13/06/11 12:56 PM, James A. Donald wrote:
> On 2011-06-12 8:57 AM, Ian G wrote:
>> I wrote a paper about John Levine's observation of low knowledge, way
>> back in 2000, called "Financial Cryptography in 7 Layers." The sort of
>> unstated thesis of this paper was that in order to understand this area
>> you had to become very multi-discipline, you had to understand up to 7
>> general areas. And that made it very hard, because most of the digital
>> cash startups lacked some of the disciplines.
>
> One of the layers you mention is accounting.

Yes, so back to crypto, or at least financial cryptography.

The accounting layer in a money system implemented in financial  
cryptography is responsible for reliably [1] holding and reporting the  
numbers for every transaction and producing an overall balance sheet of an 
issue.

It is in this that BitCoin may have its greatest impact -- it may have  
shown the first successful widescale test of triple entry [2].

Triple entry is a simple idea, albeit revolutionary to accounting.  A  
triple entry transaction is a 3 party one, in which Alice pays Bob and  
Ivan intermediates.  Each holds the transaction, making for triple copies.

To make a transaction, Alice signs over a payment instruction to Bob with 
her public-key-based signature [3].  Ivan the issuer then packages the 
payment request into a receipt, and that receipt becomes the transaction.

This transaction is digitally signed by multiple parties, including at  
least one independent party [4].  It then becomes a powerful evidence of  
the transaction [5].

The final receipt *is the entry*.  Then, the *collection of signed  
receipts* becomes the accounts, in accounting terms.  Which collection  
replaces ones system of double entry bookkeeping, because the single  
digitally signed receipt is a better evidence than the two entries that  
make up the transaction, and the collection of signed receipts is a better 
record than the entire chart of accounts [6].

A slight diversion to classical bookkeeping, as replacing double entry  
bookkeeping is a revolutionary idea.  Double entry has been the bedrock of 
corporate accounting for around 700 years, since documentation by a  
Venetian Friar named Luca Pacioli.  The reason is important, very  
important, and may resonate with cryptographers, so let's digress to there.

Double entry achieves the remarkable trick of separating out mishaps from 
frauds.  The problem with single entry (what people do when making lists of 
numbers and adding them up) is that the person can leave off a number, and 
no-one is the wiser [7].  We can't show the person as either a bad 
bookkeeper or as a fraudulent bookkeeper.  This achilles heel of primitive 
accounting meant that the bookkeeping limited the business to the size with 
which it could maintain honest bookkeepers.

Where, honest bookkeepers equals family members.  All others, typically,  
stole the boss's money.  (Family members did too, but at least for the  
good of the family.)  So until the 1300s and 1400s, most all businesses  
were either crown-owned, in which case the monarch lopped off the head of 
any doubtful bookkeeper, *or* were family businesses.

The widespread adoption of double-entry through the Italian trading ports 
led to the growth of business beyond the limits of family.  Double entry 
therefore was the keystone to the enterprise, it was what created the 
explosion of trading power of the city states in now-Italy [8].

Back to triple entry.  The digitally signed receipt dominates the two  
entries of double entry because it is exportable, independently  
verifiable, and far easier for computers to work with.  Double entry  
requires a single site to verify presence and preserve resiliance, the  
signed receipt does not.

There is only one area where a signed receipt falls short of complete  
evidence and that is when a digital piece of evidence can be lost.  For  
this reason, all three of Alice, Bob and Ivan keep hold of a copy.  All  
three combined have the incentive to preserve it;  the three will police  
each other.

Back to BitCoin.  BitCoin achieves the issuer part by creating a  
distributed and published database over clients that conspire to record  
the transactions reliably.  The idea of publishing the repository to make 
it honest was initially explored in Todd Boyle's netledger design.

We each independently converged on the concept of triple entry.  I believe 
that is because it is the optimal way to make digital value work on the 
net;  even when Nakomoto set such hard requirements as no centralised 
issuer, he still seems to have ended up at the same point: Alice, Bob and 
something I'll call Ivan-Borg holding single, replicated copies of the 
cryptographically sealed transaction.

With that foundation, we can trade.

> Recall that in 2005
> November, it became widely known that toxic assets were toxic.

In 2005, the SEC looked at my triple entry implementation, and....

>  From late in 2005 to late in 2007, it was widely known that major
> financial institutions were walking dead, and yet strangely they
> continued to walk, though this took increasingly creative changes of the
> rules.

...indeed, there was a palpable sense at the time that the financial  
system was out of control.  They were looking at this thing with worried  
eyes.

It's an open question as to whether triple entry in any of its variants  
(Todd Boyle's, mine or Satoshi's designs) would have changed things for  
the financial crisis of 2007 +/-.  I think the answer is;  it was way too 
late to effect it.  But, it wouldn't have hurt, and with other things added 
in [9], the sum would have changed things, assuming widespread 
implementation.

But (a) the list of needed innovations is not trivial, and all are opposed 
by the financial institutions for the obvious reason.

Also, (b) it has to be said that at the bottom of the financial crisis is 
securitization, which changes everything about finance [10].  And I do mean 
everything :)  Without understanding the role that securitization plays, 
talking about triple entry or toxic assets or ratings agencies or bad 
behaviour or poor people or whatever is pretty much doomed to irrelevance.

Which is how they like it!

> Today in 2011, there is still no audit that acknowledges that toxic
> assets were and are toxic.

This one winds all the way to [11] ...

> While doubtless a good monetary system should embrace all these aspects
> of knowledge, our existing monetary system does not.

iang

[1] reliably here means to play its part in the overall security model  
against attacks of fraud, etc.
[2] this rant is essentially a highly compressed version of:
http://iang.org/papers/triple_entry.html
[3] there is an intermediate step here where Bob can also sign the payment 
into a deposit instruction, thus confirming acceptance.  But this can be 
optimised out.
[4] think here of European Notaries, responsible to both parties to  
intermediate.
[5] crypto people would recall the term "non-repudiable" although that is 
out of favour; "non-repudiation is repudiated :).  BitCoin paper uses the 
term "non-reversible."  Finance prefers terms like "final settlement.  
Legal people look for "evidence."  I choose the legal term here because in 
a dispute their opinion matters more.
[6] this is not really apparent on paper, only in code and implementation 
(aka issues).
[7] all of this logic is applicable & analogous & consistent when the  
bookkeepers are computers...
[8] accounting history does not accept this point as proven.  Having seen 
the difference of both double entry and triple entry in accounting  
systems, I'd say its clear.  But historians don't have the benefit of  
seeing accounting systems stuff up in glorious fashion, they only have the 
dry old parchments to work from.
[9] another of the things essential on the list is final settlement /  
irreversibility / non-repudiation, as pioneered in many digital cash  
schemes.  c.f., Mutual Funds Scandal.
[10] Everything important about the financial crisis in 4 short essays,  
start here:
http://financialcryptography.com/mt/archives/001297.html
[11] http://financialcryptography.com/mt/archives/001126.html
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