The Unsung Hero of Decentralized Bridging

Bridging operates like quantum teleportation: the coin doesn’t physically move; it is locked in the source network, while an equivalent amount appears in the destination network. However, for this to happen, both sides must be perfectly synchronized. This is where messaging comes into play, as it allows the bridge to communicate to the destination network what has occurred in the source network.

Without this invisible layer of communication, teleportation would fail — the asset could be lost or duplicated. The transmission of messages is what enables two completely independent smart contracts across different blockchains to behave as part of a unified system.

The team from [Allbridge](https://core.allbridge.io/) explains how messaging works and why decentralized bridging is impossible without it.

Messaging refers to the process of transmitting information (but not tokens) from one blockchain to another. For instance:

Messages cannot simply be forwarded; they need to be confirmed before the destination network can trust them.

**Finality and Validators**

Validators, sometimes referred to as guardians or oracles depending on the protocol, are responsible for confirming messages. Before a message can be processed in the destination network, the transaction must be deemed finalized — meaning it cannot be reversed or altered due to a blockchain rollback.

Criteria for finality can vary between networks, and the messaging protocol must take these differences into account. In the destination network, a group of validators confirms the transaction and cryptographically signs the message.

**Relayer**

Another key component of the bridge is the relayer, which sends the signed message to the smart contract on the destination network, verifying the validators’ signatures. If everything checks out, the message is accepted and executed. The relayer pays the gas fees and receives a small fee as compensation, which the user sees during the transfer.

**What Does the Message Contain?**

A message is merely a structured set of bytes. The sending contract encodes it, and the receiving contract decodes it. It contains only the essential information for executing the task in the destination network. Bridges work to optimize message handling, reducing costs and increasing efficiency.

Transmitting messages between blockchains is a powerful tool, albeit costly. Every byte stored or verified on the blockchain incurs gas fees, making scalability and efficiency crucial for speed-oriented bridges.

**The Issue: Large Messages**

A typical message can exceed 100 bytes in its original form, which can make each transaction expensive.

**The Solution: Hashed Messages**

Rather than 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 IDs of the source and destination networks. This allows for direction verification directly from the hash without complete decoding: a simple technical tweak results in significant gas savings.

**The Trade-off**

Hashing reduces message storage costs. Since the destination network only sees the hash, the relayer must still provide the original message so that the smart contract can recount and verify the data. While this approach makes blockchain interactions cheaper, it increases the burden on the relayer.

**The Advantage of Flexibility**

Most solutions are tightly bound to specific messaging protocols, which can be limiting, especially when different blockchains utilize diverse protocols. A bridge that isn’t reliant on any single protocol can operate across multiple systems simultaneously.

**Benefits:**

The goal of messaging is to allow blockchains to «communicate» and achieve decentralized cross-chain coordination. Smart contracts across different networks exchange information without needing to know anything about each other — only the receipt of a verified message matters. This transforms isolated blockchains into integral parts of a single system without compromising decentralization.

Ultimately, the key lies in the internal architecture that facilitates the transfer of information about transactions between blockchains while keeping critical logic on smart contracts.