Superstate Short Duration U.S. Government Securities Fund (USTB) USTB

Claim: No public cryptographic inventory or quantum threat model has been published by Superstate.

Coverage basis: Project self-assessment (absent)

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: cap-applying

Quantum blocker: No public cryptographic inventory — Readiness & Risk Cap: 10

Assurance: Web search across superstate.com, docs.superstate.com, and github.com/superstateinc confirms zero mentions of 'quantum', 'post-quantum', 'PQC', or 'cryptographic inventory'. Evidence of absence is strong given the project's otherwise thorough public documentation.

Third-party risk identification exists (Eternax.ai 'Highly Critical Quantum Risk 5/5', Yearn risk report notes EOA centralization) but does not substitute for a project-published inventory.

• https://docs.superstate.com/investors/smart-contracts
• https://docs.superstate.com/investors/security.md
• https://superstate.com/assets/ustb
• https://github.com/superstateinc/ustb

Claim: No quantum-specific evidence record has been published by the project.

Coverage basis: Project self-assessment (absent)

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Assurance: No quantum-specific code references, specs, audits, transaction examples, or reproducible analytics published by Superstate.

The project's classical audit archive (11 reports) and open-source code constitute a strong classical evidence record but contain zero quantum content.

Claim: USTB uses standard ECDSA (Ethereum/Plume) and Ed25519 (Solana) for all spend authorization and permit signatures (EIP-2612). No PQC or hybrid-PQC signatures are implemented.

Coverage basis: Host-chain inherited + token-specific EIP-2612 permit

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Quantum blocker: All spend authorization is ECDSA/Ed25519-only — Readiness & Risk Cap: 40

Assurance: Verified on-chain: USTB Token Proxy at 0x43415eB6ff9DB7E26A15b704e7A3eDCe97d31C4e implements standard OpenZeppelin ERC-20 with EIP-2612 permit() using ECDSA. 0xMacro audit A-2 (Jul 2024) confirms EIP-2612 ECDSA permit signatures. Solana SPL Token-2022 uses Ed25519.

Token inherits host-chain signature scheme. No token-specific custom cryptography beyond ERC-20 standards.

• https://github.com/superstateinc/ustb
• https://etherscan.io/address/0x43415eb6ff9db7e26a15b704e7a3edce97d31c4e
• https://0xmacro.com/library/audits/superstate-2
• https://docs.superstate.com/investors/smart-contracts

Claim: Standard Ethereum secp256k1 and Solana Ed25519 account models. Long-exposure public keys for all transacted addresses including admin EOAs.

Coverage basis: Host-chain inherited

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Quantum blocker: All 4 admin EOAs have exposed on-chain public keys with extensive transaction history — long-exposure targets

Assurance: All 4 admin EOAs confirmed on-chain with code size 0 (Yearn risk report, April 2026). USTB Token Owner has 161+ transactions, AllowList Owner has 221+, RedemptionIdle Owner and Oracle Owner also have transaction history — public keys are fully exposed.

No PQ key-derivation scheme, no stealth addressing, no address rotation mechanism. Institutional holders' addresses are visible on-chain through AllowList-gated transfers.

• https://etherscan.io/address/0xad309bb6f13074128b4f23ef9ea2fe8552afca83
• https://etherscan.io/address/0x7747940adbc7191f877a9b90596e0da4f8deb2fe
• https://etherscan.io/address/0x8cf40e96e7d7fd8A7A9bEf70d3882fbBC4D40765
• https://etherscan.io/address/0x4B1df64357a5D484563c9b7c16a80eD8B8fB1395

Claim: USTB is a token, not a consensus network. Consensus authentication is handled by host chains (Ethereum, Solana, Plume).

Coverage basis: N/A — token does not operate consensus

Implementation score: 0 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Claim: USTB relies on host-chain state integrity (Ethereum EVM storage, Solana account model). No custom cryptographic commitment schemes, accumulators, or KZG/pairing-based verification.

Coverage basis: N/A — no custom state-integrity cryptography

Implementation score: 0 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Verified from source code at github.com/superstateinc/ustb — SuperstateToken.sol extends ERC20Upgradeable, PausableUpgradeable, Ownable2StepUpgradeable. No custom cryptographic primitives.

• https://github.com/superstateinc/ustb

Claim: USTB has no privacy layer, ZK proofs, shielded transactions, note encryption, viewing keys, or stealth addresses.

Coverage basis: N/A — no privacy layer exists

Implementation score: 0 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: The absence of a privacy layer means harvest-now-decrypt-later attacks can collect complete institutional transaction histories from public ledgers. This is noted as a privacy risk in the Eternax.ai assessment but does not create a separate QRI-scored privacy subfactor since no privacy layer exists to evaluate.

While USTB has no privacy layer to score, the public visibility of institutional flows creates a permanent harvest-now-decrypt-later exposure that off-chain recovery cannot retroactively fix.

Claim: USTB is a token, not a P2P network. Node identity and peer authentication are handled by host chains.

Coverage basis: N/A — token does not operate a P2P network

Implementation score: 0 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Claim: Admin keys are 4 EOAs managed via Turnkey TEE-based secure enclaves. No PQ-protected signing path, no hybrid-PQC custody workflow, and no hardware-wallet support for PQC signatures.

Coverage basis: Token-specific admin key custody

Implementation score: 0 · Evidence confidence: Medium

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Quantum blocker: 4 EOA admin keys with no multisig, no timelock, no PQC custody path

Assurance: Turnkey TEEs protect key material at rest (extraction resistance) but the signing algorithm remains ECDSA secp256k1. A quantum computer running Shor's algorithm derives the private key from the on-chain public key without accessing the enclave. The Yearn risk report (April 2026) confirms all 4 admin addresses are EOAs (code size 0) with no multisig on any.

Turnkey documentation referenced by Superstate security page; exact TEE architecture and attestation verifiability not independently confirmed. Even with perfect TEE security, ECDSA remains quantum-vulnerable.

• https://docs.superstate.com/investors/security.md
• https://github.com/yearn/risk-score/blob/master/reports/report/superstate-ustb.md

Claim: ~$741M–$988M total AUM; 0% is quantum-protected. All on-chain USTB (~$620M Ethereum, ~$10M Plume, ~$3M Solana) relies on quantum-vulnerable ECDSA/Ed25519.

Coverage basis: On-chain token value + DeFi TVL

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Quantum blocker: ~$741M–$988M value 100% quantum-vulnerable

Assurance: Multiple independent sources confirm AUM: Superstate official page ($987.82M as of May 2026), DefiLlama ($772M TVL), RWA.xyz ($811M), CoinGecko ($741M market cap). Distribution: Ethereum ~83% on-chain + ~16% book-entry. Aave integration holds ~$66M USTB TVL. All on-chain value is quantum-vulnerable.

Book-entry shares (~$155M, ~16% of AUM) are not directly exposed to on-chain quantum attacks, but the same admin keys control conversion between book-entry and on-chain tokens.

• https://superstate.com/assets/ustb
• https://defillama.com/protocol/superstate-ustb
• https://app.rwa.xyz/assets/USTB
• https://eternax.ai

Claim: No critical wallets (admin EOAs, treasury, custody addresses) have been migrated to PQC or hybrid-PQC. All 4 admin EOAs remain classical ECDSA.

Coverage basis: Token-specific admin keys

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Quantum blocker: 4 admin EOAs fully classical, no migration

Assurance: Yearn risk report (April 2026) verified all 4 admin addresses on-chain as EOAs with code size 0. No multisig, no timelock on any. The USTB Token Owner controls mint, adminBurn, pause, oracle upgrade, and proxy upgrade — compromise of this single EOA is catastrophic.

No evidence of any migration planning for admin keys. No multisig adoption, no timelock addition, no PQC signing path documented.

• https://github.com/yearn/risk-score/blob/master/reports/report/superstate-ustb.md
• https://etherscan.io/address/0xad309bb6f13074128b4f23ef9ea2fe8552afca83

Claim: No quantum-specific inventory of vulnerable accounts, UTXOs, or contracts has been published. No deprecation, freeze, or burn policy exists for quantum-vulnerable holdings.

Coverage basis: Token-specific migration inventory

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Assurance: No quantum-specific inventory, deprecation policy, or migration measurement published by Superstate. The AllowList provides a technical mechanism to freeze addresses, but this has not been purposed for quantum-vulnerable account deprecation.

The adminBurn function and AllowList removal could theoretically serve as freeze/deprecation mechanisms, but no quantum-specific policy exists.

Claim: No public quantum migration or protection roadmap exists.

Coverage basis: Project roadmap (absent)

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Assurance: Web search across superstate.com, docs.superstate.com, and github.com/superstateinc confirms zero quantum migration content. The project's public roadmap (Invesco transition, DeFi integrations) contains no quantum-related items.

Claim: No PQ/hybrid account creation, wallet tooling, transaction paths, custody paths, user-facing warnings, education, or migration prompts exist.

Coverage basis: Token-specific migration tooling

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Assurance: No PQ account creation, no hybrid signature support in token contracts, no wallet integration for PQC, no user-facing quantum warnings in documentation or UI.

The AllowList-gated nature of USTB means all holders are known KYC'd entities — this could facilitate coordinated migration in the future but no such coordination exists today.

Claim: No quantum-specific enforcement mechanisms exist. No deprecation of legacy signing, no restricted withdrawals, no mandatory migration deadline. However, Superstate maintains off-chain records and can forcibly burn/remint tokens or reinstate portfolios if an allowlist address is compromised.

Coverage basis: Recoverability mechanism (implemented)

Implementation score: 0.5 · Evidence confidence: High

Issue classification: assurance-only caveat · Score treatment: score-reducing

Assurance: The adminBurn function and pause/unpause capabilities could theoretically enforce migration, but no quantum-specific enforcement policy or timeline exists. No exchange, custody, or bridge coordination for quantum migration has been documented. The off-chain recovery mechanism provides a PQ-Recoverable path but does not constitute quantum resistance.

Per QRI §10.1, the recovery mechanism earns partial credit (0.50) for having a credible enforcement/recovery path, but it does not prevent the initial quantum-enabled compromise. This supports the PQ-Recoverable tag.

• https://superstate.com
• https://chaoslabs.xyz
• https://github.com/yearn/risk-score/blob/master/reports/report/superstate-ustb.md

Claim: No quantum-specific incident response process exists. General security contact ([email protected]) and bug bounty program are documented but make no reference to quantum threats.

Coverage basis: Token-specific incident response

Implementation score: 0 · Evidence confidence: Medium

Issue classification: assurance-only caveat · Score treatment: note-only

Assurance: The security page documents a bug bounty program, security contact, and Turnkey key management but does not mention quantum threats, cryptographic migration, or post-quantum incident response. The off-chain recovery mechanism (redundant records + adminBurn/remint) provides a credible general recovery path but is not formalized for quantum-specific scenarios.

Per QRI §8.2, the absence of a formal quantum-specific incident-response playbook does not by itself create a Readiness & Risk Cap. It is recorded as an assurance caveat.

• https://docs.superstate.com/investors/security.md

Claim: No PQC or hybrid-PQC algorithms are implemented anywhere in the USTB token system.

Coverage basis: Token-specific algorithm selection

Implementation score: 0 · Evidence confidence: High

Issue classification: quantum-critical vulnerability · Score treatment: score-reducing

Assurance: Source code review confirms exclusive use of standard Solidity/OpenZeppelin cryptographic patterns (ECDSA, keccak256). No CRYSTALS-Kyber, CRYSTALS-Dilithium, FALCON, SPHINCS+, or any other PQC algorithm is referenced or implemented.

• https://github.com/superstateinc/ustb

Claim: 11 classical security audits exist but none address quantum-critical implementation. No quantum-specific audit has been performed.

Coverage basis: Token-specific audit coverage

Implementation score: 0 · Evidence confidence: High

Issue classification: assurance-only caveat · Score treatment: note-only

Assurance: 11 audits (0xMacro A1-A9, ChainSecurity 2023, Offside Labs May 2025) plus Certora formal verification provide exceptional classical assurance. However, all audits are scope-mismatched for quantum readiness — they verify correctness of ECDSA-based ERC-20 implementation, not PQC or hybrid-PQC security. Per QRI §6.4, scope-mismatched audits support only the audited (classical) component.

The audit program demonstrates strong security discipline that would benefit any future PQC migration, but currently provides zero quantum assurance.

• https://docs.superstate.com/investors/smart-contracts
• https://0xmacro.com/library/audits/superstate-5
• https://0xmacro.com/library/audits/superstate-6
• https://chainsecurity.com/security-audit/compound-suptb/

Claim: No quantum-critical implementation exists to evaluate for open-source reproducibility.

Coverage basis: N/A — no PQ implementation exists

Implementation score: 0 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Assurance: Classical contracts are open source on GitHub (superstateinc/ustb) with verified Etherscan deployments. This would support a future PQC implementation audit but does not earn QRI credit for a nonexistent quantum-critical implementation.

• https://github.com/superstateinc/ustb

Claim: USTB contracts use the OpenZeppelin upgradeable proxy pattern (EIP-1967). All 3 proxy contracts (USTB Token, AllowList, RedemptionIdle) can be upgraded by their respective ProxyAdmin owners. This provides architectural upgrade capability but no PQ-specific upgrade path is documented.

Coverage basis: Token-specific upgrade mechanism

Implementation score: 0.25 · Evidence confidence: High

Issue classification: none · Score treatment: score-reducing

Assurance: The upgradeable proxy pattern (EIP-1967) is well-documented, audited, and demonstrated through 5 token version upgrades (V1→V5_1) and 3 AllowList versions (V1→V3.1). The ProxyAdmin pattern enables implementation swaps. However, no PQ-specific upgrade path (e.g., planned migration to ERC-20 with PQ signature verification) is documented. Scored at 0.25 for public design/documented upgrade mechanism per Implementation Score table.

Upgrades execute immediately with no timelock — this is a classical governance concern but also means a quantum emergency upgrade could be deployed rapidly if needed.

• https://docs.superstate.com/investors/smart-contracts
• https://github.com/superstateinc/ustb
• https://etherscan.io/address/0x43415eb6ff9db7e26a15b704e7a3edce97d31c4e

Claim: No stateful signatures (XMSS/LMS or similar) are used in the USTB token system.

Coverage basis: N/A — no stateful signatures

Implementation score: 0 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable

Claim: No PQ performance or resource-impact analysis has been published.

Coverage basis: N/A — no PQ implementation to analyze

Implementation score: 0 · Evidence confidence: High

Issue classification: none · Score treatment: not applicable