Sismo is a decentralized attestation protocol that enables users to generate zero-knowledge proofs (ZKPs) from their existing digital identities and accounts. These proofs, called ZK Badges, allow individuals to selectively disclose specific credentials—such as membership in a DAO, ownership of an NFT, or participation in a community—without exposing their underlying wallet addresses or personal data. This mechanism provides granular, privacy-preserving verification for accessing services in the web3 ecosystem.
LABS
Glossary
Sismo
Sismo is a protocol for issuing non-transferable, aggregated 'badges' (Soulbound Tokens) based on off-chain and on-chain provenance, used to build a modular reputation data layer.
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definition
PROTOCOL
What is Sismo?
Sismo is a decentralized protocol for creating and managing privacy-preserving attestations, enabling users to prove specific credentials without revealing their entire identity.
The protocol operates through a modular architecture consisting of Data Groups and Attesters. A Data Group is a curated list of eligible Ethereum addresses that meet a specific criterion (e.g., "owns a specific NFT"). An Attester is a smart contract that mints Sismo Connect ZK Badges for users who prove membership in a Data Group, using a zero-knowledge proof to validate their claim. This separation allows for permissionless creation of attestation frameworks while maintaining user privacy and data sovereignty.
A primary use case is Sismo Connect, a single sign-on (SSO) for web3 applications. Instead of connecting a wallet, users can generate a ZK proof from their existing identities (like a GitHub account or a main wallet) to access an app, proving they meet requirements (e.g., "has 10+ GitHub followers") without linking those accounts. This reduces friction, enhances privacy, and prevents sybil attacks by verifying human or reputable users without doxxing them.
The protocol's utility extends to sybil resistance, reputation portability, and governance. Projects can use ZK Badges to create gated communities or voting systems where influence is based on verified, aggregated reputation from multiple sources, not just token holdings. For example, a user could prove they are an active contributor across five different DAOs to gain enhanced voting power in a new one, all while keeping each individual membership private.
Sismo's attestations are stored as non-transferable Soulbound Tokens (SBTs) on a user's zkAddress, a stealth address generated for receiving badges. This ensures badges represent immutable, non-financialized reputation. The protocol is built to be modular and permissionless, allowing any developer to create Data Groups and Attesters, fostering an ecosystem of interoperable, privacy-focused credentialing.
how-it-works
TECHNICAL ARCHITECTURE
How Sismo Works
Sismo is a decentralized protocol that enables users to aggregate and selectively disclose their digital identity across Web2 and Web3 platforms. Its core mechanism leverages zero-knowledge proofs to create portable, privacy-preserving attestations called ZK Badges.
The protocol operates through a modular architecture comprising three primary components: the Data Source Attester, the Badge Attester, and the Hydra-S2 Verifier. Users first connect their accounts from supported sources like Twitter, GitHub, or Ethereum wallets to the Data Source Attester. This component cryptographically verifies ownership and specific properties of these accounts, generating source attestations that serve as the foundational proofs of identity. This process establishes a user's Data Vault, a personal, encrypted repository for their attestations.
Using these source attestations, users can then request ZK Badges from the Badge Attester. A ZK Badge is a non-transferable (Soulbound) token that proves a specific claim—such as "owns a Nouns DAO NFT" or "has more than 100 GitHub followers"—without revealing the underlying account details or other private data. This is enabled by the Hydra-S2 zero-knowledge proof system, which allows users to generate a cryptographic proof that they satisfy the badge's criteria. The badge metadata and the ZK proof are immutably stored on-chain, typically on Ethereum Layer 2 networks like Polygon for scalability.
Applications and smart contracts, known as Verifiers, can then permissionlessly verify these ZK Badges. When a user wants to access a gated community or claim an airdrop, they simply present their badge. The verifier checks the associated ZK proof on-chain, confirming the claim's validity without learning anything else about the user's identity. This creates a powerful primitive for selective disclosure, where users can prove group membership, reputation, or achievements across different dApps while maintaining privacy and minimizing on-chain footprint compared to storing full data.
key-features
SISMO
Key Features
Sismo is a modular attestation protocol that enables users to aggregate and selectively disclose their digital identity and reputation across Web2 and Web3 applications.
core-components
SISMO
Core Components
Sismo is a decentralized attestation protocol that allows users to aggregate and selectively disclose credentials from their Web2 and Web3 accounts, enabling privacy-preserving identity verification.
01
Data Attestations
The core primitive of Sismo. An attestation is a signed piece of data issued by a Relayer that cryptographically proves a claim about a user's identity or activity (e.g., "owns an Ethereum Name Service domain"). These are stored in a zkAttestation Registry on-chain, forming a portable, verifiable reputation layer.
02
ZK Badges
Non-transferable, privacy-preserving Soulbound Tokens (SBTs) minted based on attestations. They prove membership or reputation (e.g., "Gitcoin Grants Round 18 Contributor") without revealing the underlying source accounts. Zero-Knowledge Proofs (ZKPs) enable this selective disclosure, allowing users to prove they hold certain credentials without linking them to their main wallet.
03
Data Sources & Groups
Sismo connects to various Data Sources to generate attestations:
- Web3: On-chain activity from wallets (e.g., NFT ownership, DAO voting).
- Web2: Verified accounts from platforms like Twitter, GitHub, or Discord. Users with a common trait from a data source form a Group, which is the basis for issuing ZK Badges to all members.
04
Sismo Connect
A developer framework for integrating Sismo's attestation protocol into applications. It allows apps to:
- Request specific ZK Badges or attestations from users.
- Verify proofs in a gasless manner.
- Enable one-click logins and gated access based on proven, aggregated reputation, moving beyond simple wallet connections.
05
The Relayer Network
A decentralized network of operators that generate Zero-Knowledge Proofs for users. Relayers perform the computational work required to create attestations and mint ZK Badges, allowing users to claim credentials without paying gas fees, ensuring a seamless and accessible user experience.
06
Proof of Provenance
The cryptographic guarantee that a ZK Badge was legitimately minted from a verified Data Source. The entire attestation lifecycle—from data sourcing to proof generation—is cryptographically verifiable, ensuring the integrity and trustlessness of the reputation data without relying on a central issuer.
primary-use-cases
SISMO
Primary Use Cases
Sismo is a protocol for creating and using zero-knowledge attestations, enabling users to prove specific facts about their identity or assets without revealing the underlying data. Its primary applications focus on privacy-preserving access, reputation portability, and sybil resistance.
CLASSIFICATION
Types of Sismo Badges
A comparison of the primary badge types in the Sismo protocol, distinguished by their minting mechanism, data source, and use case.
| Feature | Data Source Badges | Level Badges | Skill Badges |
|---|---|---|---|
Core Data Source | Off-chain attestations (e.g., Twitter, GitHub) | On-chain activity (e.g., DeFi, NFT holdings) | Protocol-specific interactions (e.g., governance, quests) |
Minting Mechanism | Provenance Proof via ZK Connect | Aggregated activity scoring | Direct on-chain verification |
Primary Use Case | Identity verification & sybil resistance | Reputation & contribution tiers | Skill certification & access gating |
Verification Privacy | |||
Transferable | |||
Mint Cost (approx.) | Gas only | Gas only | $10-50 (protocol fee + gas) |
Example | "Twitter Early Adopter" | "Uniswap LP Tier 3" | "Aave Safety Module Guardian" |
ecosystem-usage
SISMO
Ecosystem Usage
Sismo is a decentralized attestation protocol that enables users to aggregate and selectively disclose their digital identity across Web2 and Web3. Its core components, ZK Badges and Data Vaults, facilitate privacy-preserving proof generation for applications in governance, airdrops, and access control.
04
Governance & DAO Integration
DAOs use Sismo for sybil-resistant and privacy-focused governance. By requiring ZK Badges that prove membership or contribution history, DAOs can:
- Distribute voting power based on verified, anonymous reputation (e.g., '10 votes for proven contributors').
- Create granular governance roles (e.g., 'Core-Contributor', 'Early-Supporter').
- Prevent whale dominance by weighting votes on proven participation rather than mere token holdings.
05
Airdrop & Loyalty Programs
Protocols leverage Sismo to design fair airdrops and loyalty rewards that target real users while mitigating sybil attacks. Instead of simple snapshotting, they can:
- Require proof of past on-chain activity (e.g., 'swapped on Uniswap before date X').
- Aggregate cross-platform history (e.g., 'GitHub contributor AND Ethereum user').
- Reward user segments anonymously, preserving privacy while ensuring eligibility.
06
Related Concepts
Sismo operates at the intersection of several core Web3 primitives:
- Soulbound Tokens (SBTs): Non-transferable tokens representing identity; ZK Badges are a privacy-enhanced type of SBT.
- Zero-Knowledge Proofs (ZKPs): The cryptographic method enabling proof of credential ownership without data disclosure.
- Verifiable Credentials (VCs): A W3C standard for digital attestations; Sismo provides a decentralized, ZK-native implementation.
- Sybil Resistance: The defense against fake identities; a primary problem Sismo addresses through provable, aggregated reputation.
SISMO
Common Misconceptions
Sismo is a protocol for creating and verifying zero-knowledge attestations, often leading to confusion about its core functions and relationship with other identity systems. This section clarifies the most frequent misunderstandings.
Sismo is not a wallet or a traditional identity provider; it is a zero-knowledge attestation (ZKA) protocol. It does not hold user funds or manage private keys. Instead, Sismo allows users to generate cryptographic proofs about their on-chain or off-chain history (e.g., "I own a specific NFT" or "I am a member of a DAO") without revealing the underlying data. These proofs are packaged as portable, reusable Sismo Badges (non-transferable NFTs) that can be used to access applications while preserving privacy.
SISMO
Frequently Asked Questions
Common questions about Sismo, the zero-knowledge attestation protocol for building portable, private, and granular reputation systems on Ethereum.
Sismo is a protocol that enables users to generate zero-knowledge attestations (ZK Attestations) from their existing digital identities and accounts. It works by allowing users to prove specific properties about their on-chain or off-chain activity (e.g., "I own a specific NFT," "I have over 1000 followers on GitHub") without revealing the underlying data or linking their accounts together. Users generate these proofs locally using a Sismo Vault, a private, non-custodial data store, and can then mint them as Soul-Bound Tokens (SBTs) called Data Gems or use them directly in applications via the Sismo Connect integration. This creates a portable, privacy-preserving layer of granular reputation.
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