Add ERC: Privacy Address Format

[0xRowan]

This EIP defines a standardized client-side privacy address format for privacy-preserving tokens on Ethereum. The format uses a versioned prefix (pv + version number) to support cryptographic evolution and future upgrades.

Privacy Version 1 (pv1) is the initial version defined by this standard, using the Baby Jubjub elliptic curve for zk-SNARK optimization. Future versions (pv2, pv3, etc.) MAY adopt different cryptographic schemes, such as post-quantum resistant algorithms.

The format is designed for privacy-preserving token protocols, including native privacy tokens, dual-mode tokens, and wrapper protocols that add privacy capabilities to existing ERC-20 tokens.

Key Characteristics:

• Client-side specification: Address generation and parsing are performed entirely off-chain without smart contract interaction
• Version support: The "pv" prefix followed by version number (pv1, pv2, pv3) allows future upgrades for new cryptographic schemes or post-quantum resistance
• Three-key architecture: Separate spend, scan, and encryption public keys for fine-grained permission control
• zk-SNARK optimization: Baby Jubjub elliptic curve for efficient zero-knowledge proof generation
• Multi-chain support: Single-character network codes supporting 58+ EVM-compatible chains
• Compact encoding: Base58 compression with FNV-1a checksum for error detection
• Wrapper protocol compatible: Applicable to wrapper protocol that adds privacy capabilities to existing ERC-20 tokens (e.g., DAI → zDAI)

By standardizing the privacy address format at the client level, this proposal enables interoperability between privacy-preserving dApps and seamless privacy asset transfers across the Ethereum ecosystem.

[eip-review-bot]

File ERCS/erc-8999.md

Requires 1 more reviewers from @g11tech, @SamWilsn, @xinbenlv

[github-actions]

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