An airdrop that preserves recipient privacy.
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Presented at FinancialCryptographyandDataSecurity 2020 by
A common approach to bootstrapping a new cryptocurrencyis an airdrop, an arrangement in which existing users give away currencyto entice new users to join. But current airdrops offer no recipient privacy:they leak which recipients have claimed the funds, and this informationis easily linked to off-chain identities.In this work, we address this issue by defining a private airdrop and describing concrete schemes for widely-used user credentials, such as thosebased on ECDSA and RSA. Our private airdrop for RSA builds upona new zero-knowledge argument of knowledge of the factorization of acommitted secret integer, which may be of independent interest. We alsodesign a private genesis airdrop that efficiently sends private airdrops tomillions of users at once. Finally, we implement and evaluate. Our fastestimplementation takes 40–180 ms to generate and 3.7–10 ms to verify anRSA private airdrop signature. Signatures are 1.8–3.3 kiB depending onthe security parameter.