# Sigma Auth > Self sovereign identity built on Bitcoin. People and AI agents hold their own cryptographic keys and sign in to applications with a signature instead of a password. Sigma Auth, also known as Sigma Identity, is cryptographic identity infrastructure for AI agents, skills, and applications. It provides unforgeable identity attestation, NFT gated access, and standard OAuth 2.0, so an application can verify who is calling it without ever holding a password or a private key. Because an identity is a key the holder controls, the same mechanism answers the Know Your Agent (KYA) question: which agent is acting, and on whose authority. That is the difference between an agent that claims an identity and an agent that can prove one. Sigma Auth is published by Open Protocol Labs. ## Network - Open Protocol Labs: https://opl.dev - bOpen: https://bopen.ai - Kurt Wuckert Jr.: https://kurtwuckertjr.com ## Site - [Sigma Auth](https://sigmaidentity.com/): product overview and sign in. - [Documentation](https://sigmaidentity.com/docs): integration guides and API reference. ## Documentation - [API Reference](https://sigmaidentity.com/docs/access-control/api-reference): Complete Access Control API documentation - [Examples](https://sigmaidentity.com/docs/access-control/examples): Real-world integration examples for Access Control - [Access Control](https://sigmaidentity.com/docs/access-control): Verify on-chain ownership and token holdings with cryptographic proof - [NFT Verification](https://sigmaidentity.com/docs/access-control/nft-verification): Verify NFT and ordinals ownership on-chain - [Token Threshold Verification](https://sigmaidentity.com/docs/access-control/threshold-verification): Create tiered access based on NFT collection holdings - [Better Auth Integration](https://sigmaidentity.com/docs/customization/better-auth): How Sigma Auth uses Better Auth with custom Bitcoin authentication plugin - [Branding Customization](https://sigmaidentity.com/docs/customization/branding): Customize Sigma Auth's branding, styling, and content to match your organization - [OAuth Providers](https://sigmaidentity.com/docs/customization/oauth-providers): Integration with Google, GitHub, and other OAuth 2.0 providers - [Quick Start](https://sigmaidentity.com/docs/introduction/quickstart): Add Bitcoin authentication to your app in under 10 minutes - [What is Sigma Auth?](https://sigmaidentity.com/docs/introduction/what-is-sigma-auth): Bitcoin-powered authentication service that uses cryptographic signatures instead of passwords - [OAuth Restore Process](https://sigmaidentity.com/docs/key-backup/oauth-restore): Step-by-step guide to restore your Bitcoin identity using OAuth and backup password - [Key Backup Overview](https://sigmaidentity.com/docs/key-backup/overview): Secure cross-device Bitcoin key backup and restore system - [Key Backup Security](https://sigmaidentity.com/docs/key-backup/security): Technical security implementation details for the Bitcoin key backup system - [EVM Wallet Recovery](https://sigmaidentity.com/docs/key-backup/wallet-recovery): How to recover access to BSV funds derived from connected EVM wallets - [Upgrading to v2 (Production Features)](https://sigmaidentity.com/docs/migration/v2-upgrade): Migration guide for Sigma Auth v2 with PKCE, rate limiting, and enhanced security features - [Backend Auth Tokens](https://sigmaidentity.com/docs/oauth/auth-tokens): Generate Bitcoin-signed authentication tokens for backend services - [OAuth Error Handling](https://sigmaidentity.com/docs/oauth/error-handling): Complete guide to handling OAuth errors, error codes, and debugging authentication issues - [PKCE Implementation](https://sigmaidentity.com/docs/oauth/pkce): Secure OAuth flows with Proof Key for Code Exchange (PKCE) support - [Rate Limiting](https://sigmaidentity.com/docs/oauth/rate-limiting): Understanding and handling rate limits in Sigma Auth OAuth flows - [Better Auth Plugin](https://sigmaidentity.com/docs/setup/client-plugin): Install and configure @sigma-auth/better-auth-plugin for Better Auth integration - [Integration Guide](https://sigmaidentity.com/docs/setup/integration): High-level guide to integrating Sigma Auth with your application - [JavaScript Examples](https://sigmaidentity.com/docs/setup/javascript): Vanilla JavaScript integration examples for Sigma Auth - [Next.js Integration](https://sigmaidentity.com/docs/setup/nextjs): Complete guide for integrating Sigma Auth with Next.js applications - [React Integration](https://sigmaidentity.com/docs/setup/react): How to integrate Sigma Auth OAuth provider with React applications - [API Overview](https://sigmaidentity.com/docs/reference/api): Complete API documentation for Sigma Auth endpoints - [Backup API Authentication](https://sigmaidentity.com/docs/reference/backup-api): Authentication requirements and methods for the backup service API - [BAP Profiles](https://sigmaidentity.com/docs/reference/bap-profiles): Working with Bitcoin Attestation Protocol profiles in Sigma Auth - [Bitcoin Authentication](https://sigmaidentity.com/docs/reference/bitcoin-auth): Understanding Bitcoin-based cryptographic authentication - [Certificates API](https://sigmaidentity.com/docs/reference/certificates-api): BRC-52/53 identity certificate issuance, verification, and revocation - [Error Handling](https://sigmaidentity.com/docs/reference/errors): Understanding and handling errors from Sigma Auth API - [BRC-100 Wallet Key Compatibility](https://sigmaidentity.com/docs/reference/key-compatibility): How Sigma Identity keys map to BRC-100 wallets and the BAP identity system - [Profile API](https://sigmaidentity.com/docs/reference/profile-api): Creating and managing user profiles in Sigma Auth - [Security](https://sigmaidentity.com/docs/reference/security): Security considerations and best practices for Sigma Auth - [Troubleshooting Authentication](https://sigmaidentity.com/docs/reference/troubleshooting): Common authentication issues and solutions ## Full text - [llms-full.txt](https://sigmaidentity.com/llms-full.txt): every documentation page listed above, concatenated as Markdown.