Privacy, Probability and C Code in the Bitcoin Whitepaper

PREV_HASHthe Satoshi investigation

Block #005

Privacy, arithmetic, and code inside a paper

Documents on file: whitepaper, sections 9–11 (Combining and Splitting Value, Privacy, Calculations) · prev_hash: block #004

Section 10 is the only place in the document where the author writes about people rather than about a system. And what he offers is not anonymity. It is a shift: in the old model the bank sees everything and the public sees nothing; here everyone sees the transfers, and what stays hidden is who stands behind the keys. That is a precise position, and it costs the author something. He could have promised more. He promises exactly as much as the design delivers — and adds that reusing a key links transactions to each other.

Source text · whitepaper, section 10

„The public can see that someone is sending an amount to someone else, but without information linking the transaction to anyone.”

Bitcoin: A Peer-to-Peer Electronic Cash System, p. 6, Privacy

Artifact 005-A · what section 11 holds

  Poisson distribution   ->  attacker catch-up probability
  table of results       ->  confirmations vs. risk
  C program (printed)    ->  computes the same, compiles as is

The last section, and what it contains

recorded, not concluded

the attacker’s chances are modelled with a Poisson distribution — a standard tool of applied probability the result is a table: how many confirmations for a given risk the section ends with a short working program in C, printed in the paper itself the code is written to compile, not to illustrate — variable names, loop, return value

This is the detail of the whole whitepaper we would keep if we could keep only one. An academic paper does not usually end a chapter with source code. A programmer’s note does not usually open with a Poisson distribution. Here both sit on the same page, in the same voice. We record it and go no further. It does not tell us who the author was. It tells us what kind of practice this document came out of — and gives us something to compare against, once we reach the client’s code.

Block sources: bitcoin.org/bitcoin.pdf

Finding #6 — pinned to the boardThe privacy section promises pseudonymity, not anonymity, and names its own limits (key reuse links transactions). The final section combines applied probability with a short working C program printed inside the paper — two practices in one document. Material for later comparison with the client code.

In block #006The conclusion, and then the shortest chapter of all: eight references. Who the author cites, who he does not, and in what order — the map of what he had read. Friday, 14:10.

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