Gemini is a licensed digital asset exchange that issues asset backed cryptocurrencies, such as the ERC-20 based Gemini Dollar (GUSD), a stablecoin pegged one-to-one with the US dollar. The project was launched with the intention to innovate in operational oversight and transparency, viewing inadequate trustworthiness as the central shortcoming in competing stablecoins. The Winklevoss twins founded Gemini, whose previous ventures include ConnectU, a predecessor to Facebook. The New York State Department of Financial Services licensed Gemini as an official, regulated trust company in May of 2015.
Asset-backed stablecoins typically introduce some degree of counterparty risk—issuers vary in their practices of disclosing and evidencing the actual balance of stablecoins issued to assets held, ease of redeeming underlying assets, available legal recourse in contexts of insolvency, or with transparency about the location of asset holdings. Gemini believes viable stablecoins will require trustworthy issuers, with both cryptographic proofs and regulatory oversight providing holders confidence in issuers.
The New York State Department of Financial Services regulates Gemini’s Trust Company, providing some such oversight. Assets backing GUSD are held at the State Street Bank and Trust Company, and BPM, an independent accounting firm, performs monthly audits to verify the 1:1 pegging. The smart contracts underlying the Gemini Dollar also enable Gemini to freeze, block, or reverse token transfers in response to security incidents, an ability Gemini requires in order to comply with regulations. Trail of Bits, an information security research firm, audits these contract’s code.
The amount of GUSD issued and in circulation is publicly available on the Ethereum blockchain, which, in conjunction with regular, public, auditor-issued reports on Gemini’s actual asset holdings, offers those interested proof-of-solvency. A three-layer stack of smart contracts defines the stablecoin. The top ‘Store’ layer contain a ledger mapping token owners to their balances that enables users to view transaction history. The middle ‘Impl’ layer—presumably standing for ‘Implementation’—contains the code comprising the Gemini dollar’s behavior and state, and, when given the right to execute, performs transfers or creates new tokens. The Impl layer does not directly control ledger data, but rather delegates ownership to the ‘Store’ layer. Finally, the bottom ‘Proxy’ layer acts as GUSD’s public face, providing an interface where users can initiate transfers or view the ledger, with actions taken on the Proxy layer governing what takes place on the Impl layer.
Gemini’s token, GUSD, is an asset-backed stablecoin issued and traded on the Ethereum blockchain. Pegged to the US Dollar, total supply varies over time as users deposit or redeem US Dollars into or out of GUSD. To document that the supply of printed GUSD does not exceed Gemini held US dollars, printing is controlled through both online and offline keysets, with the online key enabling the Impl layer to print GUSD up to a limit adjustable only through the offline keyset, while auditor's reports are publicly available.