Technical details on smart contracts for Ethereum-based repo tokenization pilots

Technical details on smart contracts for Ethereum-based repo tokenization pilots (e.g., Société Générale–Forge/Banque de France 2024 repo, UBS, Les Gardiennes collaborations, and related UBS uMINT/Project Guardian work) are not fully open-sourced or published in complete audited code form. These are institutional, regulated deployments focused on compliance, so details come from whitepapers, audits, press releases, and Etherscan-verified contracts rather than public GitHub repos (unlike retail DeFi protocols).

The pilots primarily rely on standard-compliant ERC-20 tokens (or extensions) for collateral (e.g., tokenized bonds/funds) and settlement assets. Repo mechanics involve on-chain token transfers/pledges (via smart contract calls for collateral posting, interest, and redemption) with interoperability to off-chain/CBDC systems (e.g., Banque de France’s DL3S). Automation uses role-based access control, whitelisting, and upgradeable patterns for regulatory compliance (KYC/AML, sanctions, transfer restrictions). No single “repo contract” is publicly detailed; instead, platforms like SG-Forge’s CAST framework or UBS Tokenize handle issuance, registry, and settlement logic.

1. Société Générale–Forge (SG-Forge) Ethereum Contracts (Used in 2024 Repo Pilot Collateral)

The 2024 repo pilot pledged bonds issued on public Ethereum (e.g., similar to SG-Forge’s prior digital bonds like the 2021 EIB issuance or French covered bonds) as collateral. SG-Forge served as registrar, fiscal agent, settlement agent, and platform manager. These bonds use their CAST Framework (Compliant Architecture for Security Tokens)—an open framework for security tokens that enforces on-chain compliance checks (KYC/AML, sanctions screening, permitted transferees) before approving transfers.

Related and representative contract (for EURCV stablecoin, a candidate for Les Gardiennes repo collateral/settlement alongside Spiko funds):

• Token Standard: ERC-20 (fungible) on Ethereum (EVM-compatible).
• Contract Name/Architecture: SmartCoin.sol (core ERC-20) with:
  • UUPS (Universal Upgradeable Proxy Standard) for upgradability.
  • AccessControlUpgradeable.sol for role-based permissions.
  • Supporting libraries: EncodingUtils.sol, data layout contracts for storage.
• Ethereum Contract Address (current EURCV deployment): 0x5F7827FDeb7c20b443265Fc2F40845B715385Ff2.
  • (An earlier EURCV deployment was at 0xf7790914Dc335B20Aa19D7c9C9171e14e278A134.)
• Key Functions/Roles (from audited code):
  • Mint/Burn: Restricted to Issuer (SG-Forge); only after off-chain fiat receipt and compliance.
  • Transfer: Freely transferable by whitelisted holders (private key-signed tx); includes pre-validation hooks for compliance.
  • Pause/Unpause, Freeze/Wipe (wipeFrozenAddress): Admin-controlled for sanctions/blacklisting.
  • Roles:
    • Registrar Operator: Whitelisting, transfer validation, mint/burn, upgrades.
    • Operations Operator: Limited transfer handling.
    • Technical Operator: Upgrade execution.
  • Allowance/transferFrom restrictions on privileged roles.
• Compliance Features: Whitelisting, blacklisting, sanctions checks via CAST. Transfers blocked for non-permitted addresses (e.g., U.S. persons excluded in some contexts). Collateral monitoring (off-chain) backs 1:1 value.
• Audits: Hacken (June 2025 for Ethereum version). Findings: 1 medium (constructor in upgradeable contract—mitigated), 1 low (wipeFrozenAddress edge case—accepted). No critical/high issues. Gas optimizations noted. sgforge.com
• Repo Relevance: Collateral bond tokens are transferred/pledged on-chain via SG-Forge platform smart contracts. The repo itself (sale + repurchase) leverages Ethereum for the collateral leg and DL3S for CBDC settlement, with interoperability (not a pure on-chain atomic swap). Earlier SG-Forge repo examples (e.g., 2021 covered bonds) used similar MakerDAO-inspired or custom pledge logic.

No public repo-specific smart contract code (e.g., no open-source repo agreement with maturity/interest logic) for the 2024 pilot.