Under the hood the contract is only half of it

Mint waits for the bank

A fiat-backed stablecoin's life runs on two layers at every step. On-chain, a contract maps addresses to balances. Off-chain, a bank confirms dollars, a compliance desk clears a name, and a reserve manager rolls bills. Neither layer is the product by itself.

Mint is the on-chain call that increases totalSupply after the issuer's bank has confirmed incoming fiat. For USDC the operator who may call it is a minter sitting under a masterMinter limit; for USDT the call is issue, from the same 3-of-6 multisig that does everything else. The contract does not watch a bank. A human confirms the wire, then an authorized key hits mint. Until that confirmation exists, no tokens appear.

Burn is the matching call that destroys tokens and decreases supply. Redemption is the off-chain payout of dollars to the verified client who sent those tokens in. Burn and payout are not one transaction. The sources put the gap at T+0 to T+5 of banking. A token can be gone on-chain on Monday while the dollars are still a wire in a queue.

Transfer is the step that does not wait. Once an address holds a balance and is not blocked, transfer is ordinary ERC-20: no issuer signature, no bank, no desk. Gasless variants exist for some tokens and are the next section. The issuer re-enters only if the address has been placed on a blacklist, in which case the call reverts.

USDC's FiatToken splits those jobs on purpose. masterMinter sets who may mint and how much; minter mints and burns inside that cap; pauser can halt transfers; blacklister can freeze an address; rescuer can pull stray ERC-20 tokens out of the contract. Circle cannot, in this design, unilaterally destroy a frozen balance. Tether's destroyBlackFunds can. That gap is the whole of the freeze section below, not a wording difference.

Reserve management never touches the token contract. Bills, repo and cash roll on a custodian's books. Those books are the 95% reserve-income line of the business chapter. Mint has to wait because the chain will not invent the dollar the bank has not posted.

What a dollar token adds to ERC-20

A plain ERC-20 needs two on-chain steps for a spender to move someone else's tokens: approve, then transferFrom, each a paid transaction. Retail payments cannot live with that. Two Ethereum standards close the gap, and they are why USDC can sit in a gasless checkout and USDT on Ethereum cannot.

Permit, EIP-2612, finalized in March 2020, lets a holder set an allowance by signing an off-chain EIP-712 message instead of sending approve. The spender submits that signature with the transfer. One on-chain transaction, one gas bill, and the holder never pays for the approval. USDC, DAI and USDS implement it. Most ERC-20s issued after 2021 do too.

A gasless transfer, EIP-3009 (transferWithAuthorization / receiveWithAuthorization), goes further. The signature authorizes a one-time, addressed transfer and never writes an allowance at all. A relayer can pay the gas in ETH while the holder signs on a phone. Circle shipped both standards together in FiatToken v2. That pair is what protocols such as x402 require for HTTP-native micropayments in USDC. USDT implements neither, and Tether has said it will not. The USDT contract on Ethereum is upgradeable, so the refusal is a product choice. On TRON the TRC-20 USDT contract has no signature-based transfer authorization of any kind, so gasless payments do not exist there in any form.

The other addition is administrative. Freeze, pause and upgrade are not in the ERC-20 spec. USDC and USDT put them in the contract because a payments issuer that cannot stop an address cannot satisfy a sanctions request. DAI never did. USDe put the emergency halt on mint and redeem, not on transfers. Chapter 3 introduced that axis as a question. This chapter names the functions.

USDT's extras all hang off one owner. USDC's extras hang off named roles. Sky's DAI hung extras off a wards mapping and never put a freeze in the token. Ethena put extras on the Minting Contract and left the USDe token itself closer to plain ERC-20. Same asset class, four permission systems.

Four tokens, four control architectures

A blacklist, also called a freeze, is a contract permission that stops an address from sending. USDC's function is blocklist. Tokens at a frozen USDC address stay there; Circle can unfreeze. USDT's functions are addBlackList and, separately, destroyBlackFunds. A USDT freeze can be escalated to a permanent burn. Counting them as the same control compares a paused balance with a deleted one.

A pause stops transfers for everyone, not for one address. USDC's pauser role can do it. USDT's owner can do it. DAI has no token-level pause. USDe's GATEKEEPER role can disable mint and redeem; that is a halt of the primary window, not of transfers of existing USDe.

Proxy upgradeability is a small contract that stores the address of the logic and forwards every call to it, so the code can be replaced while balances stay put. USDC is an OpenZeppelin upgradeable proxy (FiatTokenProxy). USDT uses an older pattern of Tether's own (deprecate plus UpgradedStandardToken). DAI is not upgradeable at all; control sits in a wards mapping, and reaching USDS required a migration. USDe's token is not upgradeable; the Minting Contract's admin role is.

A multisig is a wallet that executes only when a set number of named signers approve, written as X of Y. Tether's issuance, redemption, blacklisting, clawback and pausing all sit in one 3-of-6 multisig. That is a least-privilege miss: the key that pauses is the key that mints. USDC separates masterMinter, minter, pauser, blacklister and rescuer. How many signers control Circle's proxy-admin key is not in these sources. How many signers hold Ethena's DEFAULT_ADMIN_ROLE is not in these sources either. Both are unlocated, not zero.

DAI and USDS have to be read as two objects that share a column. Chapter 3 recorded that USDS added a freeze function DAI never had. The Polish architecture table groups DAI/USDS as without a token-level blacklist. Both statements are in the sources. They are not averaged into a single yes or no. The matrix marks that cell mixed on purpose.

The GENIUS Act requires a technical ability to block, freeze and reject on authority request. It does not require destroyBlackFunds, and it does not require a 3-of-6. Tether shipped a blacklist in 2017, years before that statute. Circle's reactive, order-driven use of blocklist is a policy choice sitting on the same statutory floor.

Company keys, a DAO timelock, and a capped multisig

Governance is who is allowed to use the powers above, and how long the rest of the market has to notice.

Circle is a company. Roles are assigned corporately. No public timelock sits in front of a FiatToken upgrade in these sources. The signer count on the proxy-admin key, as already noted, is unlocated.

Tether is a company with one 3-of-6. No public timelock is documented for USDT either. The architecture section already named the privilege problem. The operational fact is simpler: five functions share a threshold.

Sky is a DAO with a delay. A winning "spell" passes DSChief voting and then sits in the Governance Security Module for 48 hours before it can execute. A routine July 2026 edit passed with 7,023,129,526 SKY votes. That 48-hour window is the only documented timelock in this four-token set. Who holds the keys is the parallel chapter on the RWA side: BUIDL, OUSG and BENJI, read on 4–5 September 2026, put no timelock in front of seizure or upgrade. Sky does. Circle and Tether, on the public record used here, do not.

Ethena is a hybrid. Minting is limited to whitelisted "Mint Users" through an EIP-712 order. The Minting Contract's admin is upgradeable. The loss cap is the interesting number: a compromised role could mint up to 100,000 USDe uncovered and drain up to about 200,000 USD of collateral, a 300,000 USD maximum loss, before GATEKEEPER disables mint and redeem. That is a designed bound, not a promise that the admin key is safe. The signer count behind DEFAULT_ADMIN_ROLE remains unlocated.

USDe is not a payment stablecoin. DAI and USDS are not payment stablecoins. The GENIUS Act's freeze-on-demand intuition sits awkwardly on a 48-hour timelock and on a token with no freeze at all. Whether that pushes DAO-governed dollar tokens out of the US payment-stablecoin box is a later regulatory chapter. The engineering fact is already visible: real-time freeze and a 48-hour delay are different machines.

Native and bridged are different claims

A native token is a direct, separately redeemable issuer obligation on that chain. Native USDC on Arbitrum is Circle's liability, mintable and burnable against Circle's reserve, and it appears in Circle's published reserve accounting. A bridged token is a claim on a bridge that holds the original elsewhere. It is not a legal claim on the issuer. Historical USDC.e on Arbitrum, the wrapped token from before Circle launched native USDC there in June 2023, is the classroom example. Redeeming it meant burning plus a seven-day canonical-bridge withdrawal, and it did not appear in Circle's published reserves.

Circle's Bridged USDC Standard, dated 21 November 2023, is the conversion hatch: a third-party bridged contract can be formally upgraded to native issuance without breaking holders. Native USDC deployments grew from 11 chains in early 2024 to 28 in April 2026. The current count of chains on Circle's CCTP itself is given as 11 in one reading and 13+ in another; that present-tense count is not established here. The 11-to-28 native-issuance path is.

Six ways exist to move a token across chains: a canonical bridge, lock-and-mint, burn-and-mint, a liquidity network, an intent or solver route, and messaging plus a token standard. Two of them decide the claim.

Lock-and-mint locks the original in a contract on the source chain and mints a wrapped token on the destination. The locked pool is a honeypot. Wormhole-style bridges do this. Tether's USDT0 does this: real USDT sits in an Ethereum lockbox, and a wrapped claim is issued elsewhere under LayerZero's OFT standard, run by licensed operator Everdawn Labs rather than by Tether itself. USDT0 facilitated over 70 bn USD in under twelve months, which prompted a Tether Investments stake in LayerZero on 10 February 2026. The volume is real. So is the pool.

Burn-and-mint destroys the token on the source chain and mints an equivalent native token on the destination. No locked pool sits in between, because the token exists on one chain at a time. Circle's Cross-Chain Transfer Protocol, CCTP, launched in 2023 and shipped V2 on 11 March 2025, is this design. Fast Transfers settle in about 8–20 seconds. Cumulative volume was over 110 bn USD and 5.3 million transfers by 14 November 2025, per Circle. A secondary tracker put the figure at 140 bn USD on 12 June 2026. Both sit here. They are not averaged.

Ripple chose a third native path for RLUSD: Wormhole's Native Token Transfers, aiming at one canonical token across 40+ chains rather than a family of wraps. That is a native-multichain bet, not a Circle CCTP clone, and it belongs in a later who's-who chapter as a company choice.

When the bridge fails, the issuer's reserve does not help

Lock-and-mint fails in a way burn-and-mint cannot copy. If the locked pool is stolen, the wrapped token is an IOU on an empty box. The underlying native token, sitting at the issuer, is untouched.

Multichain's collapse in July 2023 drained more than 120 mn USD from its Fantom bridge. Bridged USDC on Fantom traded at about 22% of face. Underlying USDC on Ethereum stayed fully backed. Circle froze 63 mn USD tied to the exploit and had no way to restore value to the wrapped token. The freeze hit addresses Circle could see. It could not mint the Fantom wrap back to 1.00 USD, because Circle had never owed that wrap.

That is the diagnostic. A ticker that says USDC is Circle's liability only when the token is native. The three-layer test in chapter 1, pointed at a bridge, asks whose claim the holder has. Native: the issuer. Wrapped: the bridge. If the bridge is empty, the issuer's attestation of reserves is a true statement about a different object.

Lock-and-mint bridges lost a combined 2.66–2.8 bn USD to exploits in 2022–2023 (DefiLlama via CoinDesk, July 2023; Spark.money, 2026). CCTP cannot lose a pool it does not keep. USDT0 keeps one. The market has used both at tens of billions of dollars of flow. Volume is not a verdict on the claim.

Freeze scale is the last number this chapter has to carry without blending clocks. BlockSec, on 26 July 2026, had Tether blocking 9,597 addresses on Ethereum and Tron and freezing 5.69 bn USD. A 2023–2025 window in the same knowledge-base module puts Tether at 3.3 bn USD across 7,268 wallets and Circle at 109 mn USD across 372 addresses (AMLBot, 30 January 2026). Only 3.6% of blocked addresses were ever unblocked, in that material. Among Tether's 2025 blocked addresses, 84.2% (3,506) were on Tron, for 853 mn USD. Those are four readings, three windows, two issuers. They are not a single Tether total and they are not a Circle-versus-Tether rate.