Privacy Technologies

Overview

Privacy technologies stand to be one of the most important parts of the cryptoasset space. We have complied a list of resources that introduce concepts like confidential transactions, MimbleWimble, ring signatures, and zero knowledge proofs.

If there is anything you'd like to add or change, you can tweet your feedback at @messari_crypto or email [email protected].

Table of Contents

• Background
• Confidential Transactions
• Zero Knowledge Proofs
• Ring Signatures
• MimbleWimble
• Dandelion
• Bulletproofs

Background

An increasing demand for more private, confidential, secret, and anonymous ways to use bitcoin and other digital assets has pushed protocol and application developers of all stripes to ship improvements and products that afford better privacy.

Description of the differences between privacy, confidentiality, anonymity, and secrecy for blockchain transactions
Toward a Conceptual Approach to Privacy, Confidentiality, Anonymity, and Secrecy - Beni Issembert

An exploration into social and political arguments for increased privacy in bitcoin transactions
The need for privacy enhancements in the bitcoin protocol - Chris Stewart

Beginners guide to understanding what "privacy coins" are and why they matter
[Privacy Coins: What are RingCT, CoinJoin and zk-Snarks?](A beginners guide to understanding what "privacy coins" are and why they matter)

Survey of experimentation in privacy for blockchains focused on: privacy coins, smart contract privacy, privacy infrastructure, and privacy research
An Overview of Privacy in Cryptocurrencies - Richard Chen

Two-part series summary of how developers and investors should understand privacy in a cryptoeconomic system
Privacy in Cryptocurrencies: An Overview - Yi Sun & Yan Zhang
Privacy in Cryptocurrencies: Mixing-based Approaches - Yi Sun & Yan Zhang

A discussion on the theoretical importance of fungibility and how it applies to Bitcoin
Bitcoin’s Attack Vectors: Fungibility - Matt B.

Andreas Antonopoulos fields questions from an audience on the benefits and challenges with upcoming privacy improvements to Bitcoin
Bitcoin Q&A: Will governments let privacy coins exist? - Andreas Antonopoulos

Andreas Antonopoulos fields questions from an audience on the privacy concerns and opportunity from currencies like bitcoin and the opportunities they bring to emerging economies
Bitcoin Q&A: How do we protect privacy when bitcoin is traceable? - Andreas Antonopoulos

Andreas Antonopoulos fields questions from the audience on what anonymity means for cryptocurrencies and the most recent privacy tech development
Bitcoin Q&A: Anonymity and confidential transactions - Andreas Antonopoulos

Summary of of the roadmap for upcoming and expected privacy and security improvements to the Bitcoin protocol
Roadmap to Bitcoin Developments - Ian Edwards

An opinion editorial on why privacy and fungibility is arguably the most important feature for cryptocurrencies to develop
Bitcoin Fungibility: The Most Important Feature? - Jacob Donnelly

A general survey of privacy concerns and anonymity improvements for bitcoin in context of Satoshi's coins
Who Will Steal Satoshi’s Bitcoins? - Adam Ficsor

Confidential Transactions

Confidential Transactions are a privacy approach discussed by Adam Back back in 2014 that obfuscates the transaction amounts and only discloses this information to the sender, receiver, and any other parties selected to also see this information and offers simpler or more arbitrarily difficult proof by participants.

Blockstream's Adam Back discusses confidential transactions for Bitcoin on the Bitcoin Knowledge Podcast
BTCK 167 - Dr. Back On Confidential Transactions - Adam Back

Interview with Adam Gibson on the importance of Confidential Transactions for Bitcoin and other digital assets
Cypherpunks 101: 'JoinMarket and Confidential Transactions' with Adam Gibson - Block Digest

Presentation on why Bulletproofs are exciting and how they enables faster zero knowledge range proofs and more practical implementation of confidential asset features for blockchains
Bulletproofs: Short Proofs for Confidential Transactions and More - Cathie Yun

An in-depth explanation of the work behind introducing confidential assets in the Chain protocol
Hidden in Plain Sight: Transacting Privately on a Blockchain - Oleg Andreev

Greg Maxwell explains the technology behind Confidential Transactions and on-chain privacy improvements at Coinbase
Greg Maxwell on Confidential Transactions at Coinbase - Coinbase

Primer to Confidential Transactions (CT) written by a Lightning developer with the goal of providing a framework to understanding this technology
A Primer to Confidential Transactions - Ecurrency Hodler

A brief look at Confidential Transactions, a privacy-enhancing feature that can be forked into Bitcoin and other blockchains
Greater Privacy with Confidential Transactions - Matt B.

An explanation of why Confidential Transactions can improve privacy and the disagreements around how to implements this technology
Confidential Transactions/Bulletproofs: The Elephant In The Room - Adam Ficsor

Zero Knowledge Proofs

Zero Knowledge proofs are a foundational privacy method that enables proving ownership of a given piece of information without disclosing the information itself, and it several variations implemented by privacy-focused coins and privacy-enhancing improvements for other blockchains.

Presentation on the cryptographic primitives that anonymous transacting possible and a demo service on Tor/I2P that implements a security scheme to make an anti-spam anonymous forum
Truly Anonymous Credentials Using Modern Cryptography - Matthew Di Ferrante

Simplifed introduction to what zero knowledge proofs are and why they are useful for beginners
What Are Zero Knowledge Proofs? - PIVX Class

Computer science professor Eli Ben-Sasson discusses where blockchains and cryptocurrencies intersect with Zero Knowledge Proofs and related technologies like zkSNARKs
Eli Ben-Sasson: Zero Knowledge Proofs - Epicenter

Technical introduction to zero knowledge proofs and theory behind privacy enhancing utility
Introductory talk on Zero-Knowledge Proof - Ornet Nevo

An illustrated explanation of the basic technology in the most privacy-focused cryptocurrencies
Zero Knowledge Proofs (zk-SNARKS, ZenCash, ZCash) - TechnoSaviour

Beginners guide to understanding what zero knowledge proofs are and why they matter for cryptocurrencies
Introduction to Zero Knowledge Proof: The protocol of next generation Blockchain - Coinmonks

Summary of the academic history behind zero knowledge proofs and their development and utility for privacy
What are Zero-Knowledge Proofs and what is the implication? - Lucas Howell

Brief overview of the promises made by zero knowledge proof advocates and the potential utility of the technology
A Mind-Bending Cryptographic Trick Promises to Take Blockchains Mainstream - Mike Orcutt

How bulletproofs work and why they could escalate the adoption of better privacy technologies for blockchains
How Bulletproofs Could Make Bitcoin Privacy Less Costly - Michiel Mulders

An academic paper on the demands for transparency in zero knowledge systems from the public trust especially with sensitive data
Scalable, transparent, and post-quantum secure computational integrity - Eli Ben-Sasson et al.

The first in a series of posts explaining at a high level the technical design of zero knowledge systems
STARKs, Part I: Proofs with Polynomials - Vitalik Buterin

Brief summary of what zkSNARKs are and why this type of zero knowledge proof is key to Zcash's privacy design
What are zk-SNARKs? - Zcash Team

Academic paper on the development of Zerocash as a cryptocurrency implementation of zero knowledge proofs
Zerocash: Decentralized Anonymous Payments from Bitcoin (extended version) - Eli Ben-Sasson et al.

Series of articles explaining how the technology behind zk-SNARKs works
Zk-SNARKs: Under the Hood - Vitalik Buterin

Ring Signatures

Ring Signatures are a type of digital signature used by privacy coins like Monero that allow any member in a given group (or ring) of network participants to validate a transaction by someone else in a particular group without revealing who approved the signature.

Introduction to technologies that make cryptocurrencies private and anonymous, including ring signatures, CoinJoin, and zk-SNARKs
Privacy Coins Explained (Ring Signatures, CoinJoin, ZK-SNARKS) - Block Wolf

Presentation of cryptographic research into efficient ring signature designs and implementations
Efficient Ring Signatures in the Standard Model - Giulio Malavolta & Dominique Schröder

Introductory presentation on a Schnorr Ring Signatures' potential to improve on-chain privacy
Schnorr Ring Signatures - Bastien Teinturier

A very simple animated introduction to Monero and ring signatures privacy
Monero: Ring Confidential Transactions - Monero

MimbleWimble

MimbleWimble is a privacy and base-layer scalability focused blockchain protocol initially introduced in 2016 and later re-visited and revised by mathematician Adam Poelstra. MimbleWimble implementations like Grin and Beam maintain the validity of on-chain transactions borrowing from Confidential Transactions technology developed by Greg Maxwell.

Simple primer on how MimbleWimble works without diving deep into math and cryptography
How MimbleWimble Works? - Beam Privacy Team

What MimbleWimble is and its benefits explained like you're five
ELI5: MimbleWimble - James Webber

Summary of the connection between Harry Potter and cryptocurrency via MimbleWimble
A Short History of MimbleWimble: From Hogwarts to Mobile Wallets - Beni Issembert

Very simple introduction to MimbleWimble as a privacy-enhancing protocol alternative to Bitcoin
MimbleWimble explained like you’re 12 - Conor O'Higgins

Simple primer on MimbleWimble and the first implementations: Grin and Beam
What We Need to Know About Grin And BEAM - QB Exchange

Brief examination of the pros and cons of MimbleWimble as a privacy technology used by Grin and Beam
On Linkability of MimbleWimble - Alex Romanov

High-level discussion on if MimbleWimble can deliver best-in-class privacy and comparisons between MW and other privacy techniques like zk-SNARKs
MimbleWimble: The Good and the Bad - Mohamed Fouda

A thesis from Beam on a privacy ontology to help developers build from a purely privacy-based perspective for the financial world
Introduction to a Privacy Ontology - Beni Issembert

Dandelion

Dandelion is a lightweight protocol introduced by Giulia Fanti to be implemented at the base layer of a blockchain that introduces a new pattern for nodes to communicate network activity to each other while frustrating efforts to back-track transaction propagation and compromise the privacy and security of network participants.

Explanation of what Dandelion is and why it's important for Bitcoin's scaling and privacy development
Dandelions, and a Bright Future for Bitcoin Privacy - Cryptoconomy

Zack Voell talks with Giulia Fanti, a computer scientist who introduced the Dandelion protocol in eraly 2017, about efforts to improve the anonymity of Bitcoin transactions and the importance of anonymous peer-to-peer payments
Introduction to Dandelion (BIP 156) with Giulia Fanti - Zack Voell

Andreas Antonopoulos fields viewer questions in a recorded Q&A session about privacy protocols like Dandelion and MimbleWimble
Bitcoin Q&A: MimbleWimble and Dandelion - Andreas Antonopoulos

Giulia Fanti presents on the potential for Dandelion to considerably improve transaction privacy for on-chain transactions in Bitcoin
Dandelion - Building on Bitcoin - Giulia Fanti

Bulletproofs

Bulletproofs are type of zero knowledge proof designed to enable efficient confidential transactions. Unlike zero knowledge “SNARKS”, Bulletproofs do not need a trusted setup between participants, but verification is more time-intensive.

Short presentation on the potential of bulletproofs as a tool for enhancing transaction privacy for digital assets
Bulletproofs: Short Proofs for Confidential Transactions and More - Benedikt Bunz

Technical introduction to Bulletproofs
Benedikt Bünz : Bulletproofs - SF Bitcoin Developers

Analysis of some of the key issues with keeping crypto transactions private and bulletproofs as an realistic solution
Bulletproofs: Short Proofs for Confidential Transactions and More - Benedikt Bunz

Andreas Antonopoulos fields questions from the audience on what bulletproofs are and the importance of anonymity for cryptocurrencies
Bitcoin Q&A: What are Bulletproofs? - Andreas Antonopoulos

Technical explanation of Interstellar's progress on extending Bulletproofs with a constraint system API to enable zero-knowledge proofs of arbitrary statements
Programmable Constraint Systems for Bulletproofs - Cathrie Yun

A complete look at Monero’s current technology stack and the significance of Bulletproofs
Monero Becomes Bulletproof - Lucas Nuzzi

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