This repository contains the code accompanying my master thesis "Post-quantum blockchain using one-time signature chains" which describes the new post-quantum signature scheme XNYSS, designed specifically for use in blockchain technology. Wotscoin is a fork of Gocoin with support for XNYSS-based addresses. The purpose of this code is to show how post-quantum security can be added to existing bitcoin implementations by using XNYSS. A standalone version of XNYSS is available here.
While the thesis describes the use of segregated witness, this was not implemented because of time restrictions.
The wallet and client can be build as described below. The wallet can be used to
create XNYSS-based addresses (using the normal wallet -l command) and sign
transactions for those addresses (using the normal wallet -send command). By
default the wallet creates one-time addresses: to create long-term ones, uncomment
the line longterm=true in the file wallet.cfg.
When using long-term addresses, you can create a number of signatures right away, but after creating a few you need to confirm they have been adopted into the blockchain using a client (when attempting to sign you will get an error which says that no signature nodes are available). This is done as follows:
- Execute
wallet -unconfirmedto obtain a file called unconfirmed.txt - Move unconfirmed.txt to a client machine
- In the client text ui, execute
confirm /path/to/unconfirmed.txt - Move the resulting
confirmed.txtcreated by the client back to the wallet - Execute
wallet -confirm /path/to/confirmed.txt
To see how many signatures can currently be created, execute wallet -keystate.
Finally, you can create backups of the XNYSS wallet key state using the command
wallet -backup. IMPORTANT Using the backup command is the ONLY way to securely
create a backup of your XNYSS wallet: restoring a full system backup can result in
reuse of W-OTS+ private keys, which may allow an attacker to forge a signature and
thus steal funds.
For reasons described in the thesis, XNYSS is used in combination with bitcoin's multisig scripts. The wallet provided in this repository can only be used for the new XNYSS-based addresses: use the original Gocoin wallet to create and sign with regular secp256k1-based addresses.'
Changed files
- wallet/
- main.go Added command-line options
- wallet.go Changed wallet creation and printing, added confirmation and backup functionality
- signtx.go Changed signing to use XNYSS multisig
- decode.go Changed tx dump output
- config.go Added configuration options
- lib/btc/
- const.go Increased max script element size to be able to push XNYSS signatures
- funcs.go Add CHECKXNYSSMULTISIG opcode to sigop count
- multisig.go Add code to create and parse XNYSS multisigs
- opcodes.go Add CHECKXNYSSMULTISIG opcode (replacing OP_NOP1)
- script.go Add CHECKXNYSSMULTISIG opcode to ScriptToText
- wallet.go Create XNYSS-based private address in NewPrivateAddr
- lib/script/
- script.go Add XNYSS multisig script verification
- lib/xnyss/
- New files, contains XNYSS source code
- client/usif/textui/
- command.go Add command for confirmation of given public key hashes
A new record type was added to the UTXO database, being Unused Public Key Hash (UPKH) records. This database is kept to allow quick verification of signatures created for long-term XNYSS addresses (see the thesis for more details). These records are queried during script verification, and updated when a new block is accepted.
Changed files
- lib/chain/
- chain_accept.go Record UPKH db changes (add new ones, remove used ones, create undo data)
- lib/utxo/
- unspent_db.go Add UPKH handling, add UPKH entries to BlockChanges struct
- upkh_rec New file, specifies UPKH record
###The following is the original Gocoin README.
Gocoin is a full Bitcoin solution written in Go language (golang).
The software architecture is focused on maximum performance of the node and cold storage security of the wallet.
The client (p2p node) is an application independent from the wallet. It keeps the entire UTXO set in RAM, providing the best block processing performance on the market. With a decent machine and a fast connection (e.g. 4 vCPUs from Google Cloud or Amazon AWS), the node should sync the entire bitcoin block chain in less than 4 hours (as of chain height ~512000).
The wallet is designed to be used offline. It is deterministic and password seeded. As long as you remember the password, you do not need any backups ever.
client:
- 64-bit architecture OS and Go compiler.
- File system supporting files larger than 4GB.
- At least 15GB of system memory (RAM).
wallet:
- Any platform that you can make your Go (cross)compiler to build for (Raspberry Pi works).
- For security reasons make sure to use encrypted swap file (if there is a swap file).
- If you decide to store your password in a file, have the disk encrypted (in case it gets stolen).
Having hardware requirements met, any target OS supported by your Go compiler will do. Currently that can be at least one of the following:
- Windows
- Linux
- OS X
- Free BSD
In order to build Gocoin yourself, you will need the following tools installed in your system:
- Go (version 1.8 or higher) - http://golang.org/doc/install
- Git - http://git-scm.com/downloads
If the tools mentioned above are all properly installed, you should be able to execute go and git
from your OS's command prompt without a need to specify full path to the executables.
When building for Linux make sure to have gcc installed or delete file lib/utxo/membind_linux.go
Use go get to fetch and install the source code files.
Note that source files get installed within your GOPATH folder.
go get github.com/piotrnar/gocoin
Go to the client/ folder and execute go build there.
Go to the wallet/ folder and execute go build there.
Go to the tools/ folder and execute:
go build btcversig.go
Repeat the go build for each source file of the tool you want to build.
Windows or Linux (amd64) binaries can be downloaded from
Please note that the binaries are usually not up to date. I strongly encourage everyone to build the binaries himself.
Although it is an open source project, I am sorry to inform you that I will not merge in any pull requests. The reason is that I want to stay an explicit author of this software, to keep a full control over its licensing. If you are missing some functionality, just describe me your needs and I will see what I can do for you. But if you want your specific code in, please fork and develop your own repo.
The official web page of the project is served at gocoin.pl where you can find extended documentation, including User Manual.
Please do not log github issues when you only have questions concerning this software. Instead see Contact page at gocoin.pl website for possible ways of contacting me.