Stellar Bell upgrade adds muxed contract addresses and quantum-safe signature checks

What happened

Stellar's next protocol release, called Bell or Protocol 30, is heading toward two upgrade votes. The Stellar Development Foundation announced it on October 20, and the testnet vote is scheduled for November 3, 2026, with the mainnet vote following on November 23, 2026. Both votes are set for 1700 UTC.

The release bundles three proposed changes. One is a muxed contract address type under CAP-84, which lets a contract address carry a 64-bit ID written in a format starting with W. Another is CAP-87, which lets smart contracts check ML-DSA signatures, a standard NIST finalized in 2024. The third is CAP-88, which moves the ledger to a millisecond clock and alters the ledger header format.

Jake Urban, Senior Engineering Manager at the Stellar Development Foundation, described the W as an upside-down M. He said the separate type helps developers tell which address they are handling. Stellar Core v30.0.0 became available on October 16, and the Protocol 30 SDKs carry updated XDR definitions plus support for the new address type. Older SDKs may fail to decode Protocol 30 ledgers.

Why it matters

Muxed accounts already let exchanges, ramps and custodial products give each customer a unique deposit address while funds land in one account. Smart accounts had no matching feature, so a business holding customer balances needed a separate contract per customer. CAP-84 closes that gap.

The signature work is the first onchain piece of Stellar's Quantum Preparedness Plan, introduced in June 2026. Stellar secures accounts with Ed25519, secp256k1 and secp256r1 elliptic-curve signatures, and a sufficiently large quantum computer could break these in theory. No such machine is publicly known. Network transaction signatures remain Ed25519 for now, and a native post-quantum signer for classic accounts is planned for a later protocol change.

The timing change gives the network a finer clock. In September, Protocol 28 cut mainnet close times from about 5.7 seconds to 5 seconds, and the millisecond clock would let future changes target shorter intervals. Stellar Core developers are already testing faster closes on experimental branches.

What is still unclear

• Stellar has not said when a native quantum-safe signer for classic accounts will ship. The plan targets the end of 2027 for every account to be able to add one through a protocol upgrade while keeping the same address and history, and 2026 for enterprise wallets to move to quantum-safe signing through Soroban contract accounts.
• The reports do not say whether the November votes will pass or what share of validators supports the changes.

What to watch

• 2026-11-23 Mainnet upgrade vote scheduled for 1700 UTC.

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