Ás-brú

Ás-brú is Scriptum’s fast-rail bridge between Scriptum on-chain and currencies held at centralised exchanges.

It enables a holder of Scriptum to trade directly with a holder of fiat or another cryptocurrency at a named exchange — without an attestor, without exchange cooperation, and without leaving the Scriptum protocol layer.

The structure is two-party.
A locks Scriptum in a protocol-controlled escrow.
B transfers the off-chain side at the named exchange.
Miners watch the exchange’s public API for the matching transfer. When the chain sees confirmation, the Scriptum is released to a stealth-derived Scriptum address controlled by B.

Half-atomic, honestly named.
The Scriptum side is cryptographically enforced — escrow, miner-witnessed release, and deterministic timeout if the trade does not complete within the defined window.
The off-chain side relies on the exchange’s public API and miner observation. The chain does not pretend cryptographic atomicity across both legs.

The name Ás-brú is Old Norse for Bifröst — the bridge of the Æsir, connecting Midgard to Asgard.
A reliable, narrow-purpose connector between two domains, bearing load while it stands, with known limits.
The Scriptum primitive follows the same philosophy: a structural bridge from the on-chain economy to exchange-rail liquidity, deliberately bounded so it does not exceed its load.

Where Ás-brú lives

Ás-brú is a chain primitive.
The user-facing experience lives inside Aurum — exchange selection, trade construction, window monitoring, and settlement receipt.
From the holder’s perspective, Ás-brú appears as a fast exchange-side workflow integrated directly into the wallet.

Tier-1 exchanges

Aurum integrates only exchanges admitted to the chain’s Tier-1 registry — exchanges that satisfy regulatory, security, and API-stability requirements.

Initial Tier-1: Kraken.
Subsequent additions are governance decisions of the Curia.

Window of trust

Every Ás-brú trade operates within a fixed 60-block settlement window (~10 minutes at 10-second blocks).

Trades requiring longer trust horizons should use Horkos instead.

Status

Ás-brú is specified in the whitepaper.
Implementation will land as Scriptum approaches Genesis, with Kraken serving as the initial integration target.