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[segnet3 hard-fork] Allow additional data in coinbase witness #60

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@ajtowns ajtowns commented Mar 15, 2016

Based on:
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-January/012301.html
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2016-February/012313.html

An alternative to #48 . It's probably not acceptable as is, but hopefully useful for discussion?

This aims to be a reasonably simple patch set that allows future soft-forks to have additional commitments made by including them in the coinbase witness.

With this patchset, the coinbase witness stack can contain up to 255 elements, of any size, however the coinbase must commit to the number of elements. The coinbase commits to the merkle root of a tree whose first leaf is the merkle root of the tree of all the witnesses for the other transactions, and whose remaining leaves are the coinbase witness stack elements.

jtimon and others added 28 commits March 16, 2016 18:34
Rebased by Pieter Wuille.
Cleanup by Matt Corallo.
Contains refactorings by Eric Lombrozo.
Contains fixup by Nicolas Dorier.
Includes simplifications by Eric Lombrozo.
Includes support for pushkeyhash wit v0 by Alex Morcos.
Includes fixup by Suhas Daftuar.
Includes fixup by Thomas Kerin.
…en verify_script receives VERIFY_WITNESS flag

script_tests: always test bitcoinconsensus_verify_script_with_amount if VERIFY_WITNESS isn't set

Rename internal method + make it static

trim bitcoinconsensus_ prefix

Add SERIALIZE_TRANSACTION_WITNESS flag
Witness blocks can be greater than 2MiB, but cannot be validly greater
than 4MB.
ajtowns added 4 commits March 17, 2016 12:47
Break out witness commit position search and witness commitment and
nonce check into separate functions.
Rather than having the coinbase witness commitment be the hash of the
concatenation of the transaction witness merkle root and a single 32-byte
nonce from the coinbase witness, treat it instead as the merkle root
of a tree with the leaves being the transaction witness merkle root,
and each of the items from the coinbase stack.

For the case where the coinbase witness stack contains a single, 32-byte
item this change has no effect, however it should generalise well to allow
the coinbase witness stack to contain an arbitrary number of elements.

(If an element on the coinbase stack is not already exactly 32 bytes,
it is first hashed before being added as a leaf to the merkle tree)
This relaxes the restriction on the coinbase witness that limited it to
only having one entry that must be 32 bytes; instead there may be up to
255 items on the coinbase witness stack, and they may be any length.

In order to have multiple entries on the coinbase witness stack, the
number of entries must be specified in the coinbase commitment, by
changing the witness commitment from a 36 byte push:

  OP_RETURN [ 0xaa 0x21 0xa9 0xed HASH ]

to a 37 byte push:

  OP_RETURN [ 0xaa 0x21 0xa9 0xed HASH N ]

where N is the number of entries on the coinbase witness stack (from 0
to 255).
@ajtowns ajtowns force-pushed the segwit-coinbase-witness branch from a5462fd to 86c55b0 Compare March 17, 2016 02:52
@sipa sipa force-pushed the segwit branch 4 times, most recently from a88b686 to 38a8b36 Compare March 26, 2016 00:22
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sipa commented Mar 29, 2016

I have not included this in segwit4, but we should keep thinking about this.

@sipa sipa force-pushed the segwit branch 5 times, most recently from c700b59 to 85b6ae6 Compare April 4, 2016 14:52
@sipa sipa force-pushed the segwit branch 2 times, most recently from 1b904a5 to fb4873e Compare April 17, 2016 23:21
sipa pushed a commit that referenced this pull request Apr 22, 2022
…d enum

0e5dedb qt/wallettests: sort includes (William Casarin)
0554251 qt: Skip displayUnitChanged signal if unit is not actually changed (Hennadii Stepanov)
ffbc2fe qt, refactor: Remove default cases for scoped enum (Hennadii Stepanov)
152d5ba qt, refactor: Remove BitcoinUnits::valid function (Hennadii Stepanov)
aa23960 qt, refactor: Make BitcoinUnits::Unit a scoped enum (Hennadii Stepanov)
75832fd qt: Use QVariant instead of int for BitcoinUnit in QSettings (Hennadii Stepanov)

Pull request description:

  This is a rebased version of #60

  Since Qt 5.5 there are [means](https://doc.qt.io/qt-5/qobject.html#Q_ENUM) to register an enum type with the meta-object system (such enum still lacks an ability to interact with [QSettings::setValue()](https://doc.qt.io/qt-5/qsettings.html#setValue) and [QSettings::value()](https://doc.qt.io/qt-5/qsettings.html#value) without defined stream operators).

  In order to reduce global namespace polluting and to force strong type checking, this PR makes BitcoinUnits::Unit a scoped enum (typedef BitcoinUnits::Unit BitcoinUnit;).

  No behavior change.

ACKs for top commit:
  jonatack:
    ACK 0e5dedb, review and debug build of each commit after rebase on current master, lightly tested running the GUI, changing units a few times, and verifying persistence after restarting
  promag:
    Code review ACK 0e5dedb

Tree-SHA512: 39ec0d7e4f0b9b25be287888121a8db6b282339674e37ec3a3554da63a9e22d6fe079e8310ca289b2a0356a19b3c7e55afa17d09dd34e0f222177f603bb053a3
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10 participants