Transaction Graph Obfuscation

A privacy-enhancing protocol where multiple users combine their transactions into a single, larger transaction. This technique obfuscates the transaction graph by making it computationally difficult to determine which input corresponds to which output.

• How it works: Several participants create a joint transaction with many inputs and outputs. A coordinator or a peer-to-peer protocol facilitates the construction.
• Example: Wasabi Wallet and Samourai Wallet implement coordinated CoinJoin rounds to enhance Bitcoin privacy.

A cryptographic method, pioneered by Greg Maxwell, that hides the transaction amounts while still allowing the network to verify that no new money is created. This is a core component of more advanced privacy systems.

• Mechanism: Uses Pedersen Commitments and range proofs to encrypt amounts. The network validates that the sum of encrypted inputs equals the sum of encrypted outputs without revealing the values.
• Implementation: Forms the basis for Mimblewimble (used by Grin and Beam) and is part of Liquid Network's confidential assets.

A powerful cryptographic proof system that enables complete transaction graph obfuscation. It allows one party to prove they possess certain information (e.g., a valid transaction) without revealing the information itself.

• Application: In Zcash, zk-SNARKs are used in shielded transactions to cryptographically sever the link between sender, receiver, and amount. The public ledger only sees a proof of validity.
• Property: Provides the strongest privacy guarantee by default, making transaction graph analysis impossible for shielded activity.

A blockchain design that inherently obfuscates the transaction graph through cut-through and Confidential Transactions. It does not have traditional addresses or scripts.

• Core Features: Confidential Transactions hide amounts. Cut-through merges and removes intermediate transaction data, collapsing the history of coin movement.
• Result: The blockchain only stores essential data to verify current ownership, significantly reducing the analyzable transaction graph. Implemented by Grin and Beam.

A cryptographic signature scheme where a signer can anonymously sign a message on behalf of a group (or ring). An external verifier can confirm a signature came from the ring but cannot identify the specific member.

• Use in Privacy: Monero uses ring signatures in its RingCT protocol to obfuscate the sender. The true signer is hidden among decoy outputs from the blockchain.
• Effect: Breaks the link in the transaction graph by creating plausible deniability for every input, as any ring member could have been the actual spender.

A protocol that generates a unique, one-time address for each transaction sent to a recipient. This prevents third parties from linking multiple payments to the same recipient by analyzing the blockchain.

• Mechanism: The sender uses the recipient's public view key and a random nonce to derive a unique public key for the transaction. Only the recipient, with their private view key, can detect and spend the funds.
• Adoption: A foundational privacy feature in Monero and Zcash (for shielded addresses), and proposed for Ethereum via EIPs.

A cryptographic method that allows one party (the prover) to prove to another (the verifier) that a statement is true without revealing any information beyond the validity of the statement itself. In blockchain privacy, ZKPs are foundational for:

• zk-SNARKs and zk-STARKs, which power private transactions and computations.
• Private state transitions, where the validity of a transaction is proven without revealing sender, receiver, or amount.
• Enabling confidential assets and shielded pools on networks like Zcash and Aztec.

A collaborative transaction batching protocol that obfuscates the transaction graph by merging payments from multiple users into a single, larger transaction. Key characteristics:

• Decentralized mixing: Users coordinate to create a joint transaction with many inputs and outputs.
• Graph disruption: It becomes computationally difficult to determine which input corresponds to which output.
• Implementation examples: Wasabi Wallet and JoinMarket use variations of CoinJoin to provide Bitcoin privacy at the protocol level, without requiring a new blockchain.

A blockchain protocol design that provides strong privacy and scalability by default. It achieves transaction graph obfuscation through two core mechanisms:

• Confidential Transactions: All amounts are encrypted (blinded) using Pedersen Commitments.
• Cut-Through: Intermediate transaction data is deleted, collapsing the entire history of coins into a single aggregate. This permanently destroys the granular transaction graph, leaving only the net effect of all transactions. Implemented in blockchains like Grin and Beam.

A cryptographic signature scheme where a signature is produced by a member of a group (a "ring") of possible signers. To a verifier, the signature is valid and proves a member of the ring signed, but it is impossible to determine which specific member. This provides plausible deniability.

• Monero's Implementation: Uses ring signatures to mix a transaction's real input with several decoy inputs from the blockchain's past, obscuring the true source of funds.
• Stealth Addresses: Often paired with ring signatures to create one-time addresses for recipients, hiding the destination.

A hardware-based privacy solution where sensitive computations (like transaction construction) occur within a secure, isolated area of a processor (e.g., Intel SGX). This approach obfuscates the transaction graph by:

• Encrypting user state: Data inside the TEE is inaccessible to the host system or other software.
• Generating private proofs: The TEE can produce a verifiable proof of correct execution without revealing the private inputs.
• Use Case: Projects like Oasis Network and Secret Network use TEEs to enable confidential smart contracts where data remains encrypted during processing.

A network-level transaction propagation protocol designed to obscure the origin (IP address) of a transaction, complementing ledger-level obfuscation. It works in two phases:

• Stem Phase: The transaction is passed randomly through a series of peers in a line graph, similar to a stalk.
• Fluff Phase: After a random number of hops, the transaction switches to standard flooding (gossip) propagation. This makes it significantly harder for a network observer to link a transaction's first broadcast to the user's actual IP address, protecting network-level privacy.