> For the complete documentation index, see [llms.txt](https://whitepaper.cudis.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://whitepaper.cudis.xyz/cudis-protocol/cudis-technology-infrastructure/ldid-longevity-decentralized-identifier.md). # LDID (Longevity Decentralized Identifier) The on-chain storage solution for users' private data aims to achieve on-chain management of user accounts and data, protect user privacy, and enhance data value. Its design includes the following key components: * **User Unique Identity on Multi-Chain**: It aims to bind users' Web2 and Web3 identities to Non-Fungible Tokens (NFTs) and Soul-Bound Tokens (SBTs), enabling identity aggregation and verifiability. This allows users to self-authenticate, establish social connections, and generate data value on-chain. * **Identity Layer of the Protocol**: CUDIS-LDID supports the mapping of multi-chain addresses and the association of off-chain third-party accounts. The protocol’s identity layer facilitates data exchange and value distribution in the gaming and AI sectors through a modular data layer, ensuring that the ownership, control, and verification rights of data are returned to users. * **Issuance of SBTs (Soul-Bound Tokens) for User Addresses**: Based on users' important information, SBTs are issued for their addresses to enable the following functions: * **Multi-chain Address Association**: Link users' addresses across different blockchains, forming a unified identity. * **Off-chain Third-party Account Association**: Associate users' off-chain accounts (e.g., social media accounts) with their on-chain identity, enriching their digital identity. * **Data NFT Indexing**: Create NFT indices for data generated by users, facilitating data management and trading. * **PSD-KV (Private Data Key-Value Storage)**: Store users' private data in a decentralized way via IPFS—such as memories of AI agents—ensuring both security and privacy.