Mimblewimble

Mimblewimble Protocol

scalability, privacy and fungibility
scales elegantly
privacy by default
strong cryptographic primitives

Mimblewimble History

white paper published anonymously by "Tom Elvis Jedusor" Aug 2016
Andrew Poelstra corrects errors, formalizes it, publishes whitepaper
Ignotus Peverell appears on IRC in Oct 2016 announcing a project
it wanted to be implemented as Bitcoin sidechain?

Mimblewimble Scalability

transaction history does not need to be stored
required data: coinbase transactions, UTXO set, proofs
cryptography over complexity

Mimblewimble Privacy, Fungibility

amounts only visible to sender & recipient
no addresses!
transactions can be aggregated, eliminated
impossible to build transaction graph

Transactions & Blocks

Mimblewimble Blocks

blocks have only the needed inputs and outputs taken together in a coinjoin
redundant inputs & outputs are eliminated, but kernels remain

Mimblewimble Tx Aggregation

Mimblewimble Cut-Thru

Mimblewimble Transactions

inputs, outputs, excess values
inputs reference UTXOs
outputs include hidden value v and blinding factor r
observers only see obscured inputs & outputs
tx can be validated by miners without knowing values
range proof: outputs - inputs = 0, proof that amounts > 0

Pederson Commitment

Greg Maxwell

r*G + v*H
building blocks of Confidential Transactions

Peterson Commitment

r*G + v*H
G, H are EC points, v is value being spent
r is a secret key (not the one from UTXO)
Pederson Commit: neither r or v can be calculated

Dandelion Protocol

transaction origin masked by Dandelion protocol

Dandelion

Grin and Beam

Grin

first implementation of MW
written in Rust
uses PoW algorithm called Cuckoo Cycle
FOSS
no foundation, no company, no ICO

Cuckoo Cycle

PoW: Cuckoo Cycle

graph theoretic proof of work system
memory-bound algorithm, designed to be ASIC-resistant
goal is to find a cycle in a bipartite graph

Grin and ASICs

2 variants of Cuckoo Cycle: Cuckatoo31+ and Cuckaroo29
initially 90% ASIC-resistant algo, two years later 100% ASIC-friendly algo

History Compression

mimblewimble has macroblock concept: consolidating to a single huge tx
node generates a macroblock periodically
Grin uses this, Beam replaced with another scheme

Beam

first blockchain launched
written in C++, FOSS
PoW: modified Equihash, changed twice
run by a company, financed by founder's reward
designed to be store of value privacy coin

Beam New Features

decoy outputs
mobile wallet features
atomic swaps

Beam Roadmap

confidential assets (POC/Testnet)
LelantusMW
multisig
trezor/ledger support (working, WIP)
payment channels - laser beam (POC)

Beam Auditing Function

building an audit function for business compliance purposes
optional auditor secret key generated, stored in kernel
wallet saves the transactions even if not included in block
additional hashes may be stored in kernels to validate documents
still a WIP, not yet implemented

Grin vs Beam: Monetary Policy

	Grin	Beam
Coin production	60 Grins per block, one block per minute	one minute block times, variable emission
Inflation rate	decreasing, exponential decay	deflationary, halving every 4 years
Total Supply	linearly increasing, uncapped	around 263 million in year 2152
Difficulty Adj	every block based on 60 block window	every block

Mimblewimble: Open Topics

Mimblewimble Wallets

sender/receiver joint construction of transactions
portability of seed phrase
multi-wallet integration

Scriptless Scripts

traditional scripts will not work
A. Poelstra figured out a method for supporting simple functions
current support:

Mimblewimble Summary

no amounts
interactive transactions (no addresses)
better scaling: tx history NOT stored, only UTXOs
proofs are small and resource efficient
no Bitcoin-style scripting (scriptless scripts)

References

grin.blockscan.com

explorer.beam.mw

Cuckoo Cycle explained by John Tromp

Questions?

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