ISM Overview

Hyperlane is secured by Interchain Security Modules (ISMs). ISMs are smart contracts that are responsible for verifying that interchain messages being delivered on the destination chain were on the origin chain.

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Core Concepts

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Default vs Custom ISM

Developers can either use the Mailbox’s default ISM or specify their own application-specific ISM. Application-specific ISM can be:

• Configured: Use pre-built ISMs with custom parameters
• Composed: Combine multiple ISMs together like security “legos”
• Customized: Create entirely new ISMs tailored to specific needs

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Configure

Hyperlane defines a set of pre-built ISMs. Developers can deploy any of these contracts “off-the-shelf” and configure them with their own parameters. For example, application developers that want increased sovereignty over interchain security could deploy a Multisig ISM configured with validators sourced from their own community.

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Compose

ISMs act as “security legos”. Developers can mix and match different ISMs together to encode a security model that best fits their needs. For example, application developers that want additional security could deploy an Aggregation ISM that requires verification by both a Multisig ISM configured with validators from the Hyperlane community, and a Wormhole ISM that verifies that a quorum of the Wormhole validator set verified the message.

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Customize

ISMs are fully customizable. Developers can write their own ISMs, tailoring them to the needs of their application. For example, application developers can build ISMs that adjust security models based on message content. High value and infrequent messages (e.g. governance) could be verified by a security model that prioritizes safety over latency and gas costs. Lower value and more frequent messages could be verified by a security model that prioritizes latency and gas costs over safety.