AdamISZ

Chaumian cash in a Bitcoin world - cashu, Fedimint

What's this for?

• More scalable/faster than a blockchain (not enough utxos)
• Much better privacy security model than a blockchain
• Same or better theft security model than TTP but much worse than a blockchain

If it's so great, why hasn't it been done yet?

RubenSomsen

Blind Diffie-Hellman Key Exchange (blind ecash)

The goal of this protocol is for Bob to get Alice to perform a Diffie-Hellman key exchange blindly, such that when the unblinded value is returned, Alice recognizes it as her own, but can’t distinguish it from others (i.e. similar to a blind signature).

Alice:
A = a*G
return A

Bob:
Y = hash_to_curve(secret_message)
r = random blinding factor

Kixunil

Reusable taproot addresses

Abstract

This document proposes a new scheme to avoid address reuse while retaining some of the convenience of address reuse, keeping recoverability purely from Bitcoin time chain and avoiding visible fingerprint. The scheme has negligible average overhead.

Motivation

notmandatory

# from target repo clone directory
# make sure you're in sync with origin
git checkout master
git fetch --all
git pull upstream master
# fetch PR to FETCH_HEAD
git fetch upstream pull/<PR#>/head
# double check the changes
git diff master FETCH_HEAD
# merge to master and push to upstream (github)

LaurentMT

Context

This third part is about known and potential attacks against the privacy provided by tools like coinjoin.


Known attacks & weaknesses

- Linkability of inputs and outputs

A good illustration of this attack is Coinjoin Sudoku (see (1) for details).

hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs