A Bridge in Need of a Hero

Bridging functions like quantum teleportation: the coin does not physically move anywhere—it is locked in the source network, while an equivalent amount appears in the destination network. For this to happen, both sides must be perfectly synchronized. Messaging comes to the rescue here, allowing the bridge to inform the destination network of events in the source network.

Without this invisible layer, teleportation would not work—the asset could be lost or duplicated. It is the message transfer that enables two completely independent smart contracts on different blockchains to behave as part of a single system.

The team at Allbridge explains how messaging is structured and why decentralized bridging is impossible without it.

What is Messaging and How Does It Work?

Messaging is the process of transferring information (but not tokens) from one blockchain to another. Here’s how it works:

1. The user initiates a transfer in the source network.
2. The smart contract accepts the tokens and creates a message—a compact data set with information about the transfer amount, destination network, recipient address, and token.

This message cannot simply be sent—it must be confirmed before the destination network can trust it.

Finality and Validators

Validators (sometimes called guardians or oracles, depending on the protocol) confirm messages. Before processing the message in the destination network, the transaction must be recognized as finalized—meaning it cannot be canceled or altered due to a blockchain rollback.

Criteria differ across networks, and the messaging protocol must account for this. In the destination network, a group of validators confirms the transaction and cryptographically signs the message.

Relayer

Another link in the bridge’s operation is the relayer, which sends the signed message to the destination network’s smart contract, verifying the validators’ signatures. If everything is correct, the message is accepted and executed. The relayer pays the gas and receives a small fee as compensation, which the user sees when making the transfer.

What Does the Message Contain?

The message is simply a structured set of bytes. The sending contract encodes it, and the receiving one decodes it. It contains only the necessary information for the task in the destination network. Bridges optimize message handling, reducing costs and increasing efficiency.

How Allbridge Core Makes Messaging Smarter

Message transfer between blockchains is a powerful tool, but not a cheap one. Every byte stored or verified on the blockchain requires gas. For a bridge focused on speed, scalability and efficiency are crucial.

The Problem: Large Messages

A typical message contains:

• the transfer amount;
• the token address;
• the recipient address;
• the source and target network IDs;
• a unique nonce.

In its original form, this information can take up more than 100 bytes, making each transaction costly.

The Solution: Hashed Messages

Instead of storing the full message, Allbridge Core converts it into a 32-byte hash—a unique and verifiable “fingerprint.” The first two bytes are replaced with the source and target network IDs. This allows for direction verification directly from the hash without full decoding: a small technical change that results in significant gas savings.

The Trade-off

Hashing reduces the cost of storing messages. Since the destination network only sees the hash, the relayer must provide the original message so the smart contract can recalculate and verify the data. This makes blockchain operations cheaper but increases the relayer’s workload.

The Advantage of Flexibility

Most solutions are tightly bound to a specific messaging protocol. This can be limiting, especially if different blockchains support different messaging protocols. A bridge not dependent on a specific protocol can work with multiple ones simultaneously.

Advantages:

• support for more blockchains;
• resilience—if one protocol fails, another can be used;
• flexibility—easily add support for new protocols without rewriting the system.

Conclusion: The Value of Messaging

The goal of messaging is to allow blockchains to “communicate” and make cross-chain coordination decentralized. Smart contracts in different networks exchange information without needing to know anything about each other—only the fact that a verified message has arrived matters. This is what turns isolated blockchains into parts of a single system—without compromising decentralization.

But most importantly, it is the internal architecture that allows for the transfer of information about transfers between blockchains, leaving critical logic to the smart contracts.