How to Architect a Non-Custodial Wallet with Social Logins

A non-custodial social wallet combines the user-friendly onboarding of Web2 with the self-custody principles of Web3. Unlike traditional wallets that require seed phrase management, these wallets allow users to sign in using familiar methods like Google, X, or email. The core innovation is that the private key is never held by a central server. Instead, threshold signatures or Multi-Party Computation (MPC) are used to split key material between the user's device and a decentralized network of nodes, ensuring no single party has full control. This architecture is often built on account abstraction (ERC-4337), which separates the logic of transaction validation from the wallet's core key, enabling features like social recovery and gas sponsorship.

The technical stack typically involves several layers. The Signer Layer is responsible for key generation and management, often using MPC protocols from providers like Lit Protocol, Web3Auth, or Privy. The Smart Account Layer uses an ERC-4337-compliant account factory contract to deploy a smart contract wallet for each user. The Session Management Layer handles user authentication via OAuth flows and can create temporary session keys to authorize specific actions without requiring a signature for every transaction. Finally, the Relayer & Bundler Layer submits user operations to the blockchain, potentially paying gas fees on the user's behalf through a paymaster.

Implementing social login starts with integrating an OAuth provider (e.g., Google OAuth 2.0) to obtain a user's verified identity. This identity seed is then used to deterministically generate a cryptographic share of a private key. The other share is held by the MPC network. When a user needs to sign a transaction, the client combines these shares to produce a signature without ever reconstructing the full private key in one place. For developers, using a service like Privy simplifies this: after OAuth, you call privy.login(user) to get a PrivyClient which can then sign messages and transactions via its built-in MPC wallet.

Security considerations are paramount. The system must be designed so the authenticating service cannot unilaterally access funds. This is achieved by ensuring the MPC nodes are operated by independent parties or using a decentralized network. Social recovery is a critical feature, allowing users to designate guardians (via their social identities) who can collectively help recover access if a device is lost. Furthermore, implementing transaction simulation and user operation bundling through services like Alchemy's Gas Manager or Stackup's Bundler can enhance security by validating intent before submission and managing gas complexities.

Here is a simplified code example for initializing a user's smart account using the viem and account-abstraction libraries after social login:

typescriptCopy
import { createSmartAccountClient } from "@alchemy/aa-core";
import { sepolia } from "viem/chains";

// After obtaining a signer from your MPC/Social provider (e.g., Privy, Web3Auth)
const smartAccountClient = await createSmartAccountClient({
  chain: sepolia,
  transport: http("ALCHEMY_RPC_URL"),
  signer: socialLoginSigner, // External owner signer from MPC
  bundlerTransport: http("BUNDLER_URL"),
});

// The client is now ready to send UserOperations
const userOpHash = await smartAccountClient.sendTransaction({
  to: '0x...',
  value: parseEther('0.001'),
});

The future of this architecture lies in deeper integration with ERC-4337's full potential, including sponsored transactions for seamless onboarding and modular signature aggregation. By abstracting away private keys and gas fees, non-custodial social wallets significantly lower the barrier to entry for mainstream users while preserving the fundamental ethos of self-custody. For developers, the ecosystem is rapidly maturing, with tools from Alchemy, Stackup, Biconomy, and Candide providing robust infrastructure to build upon.

A non-custodial wallet with social logins combines two paradigms: user-controlled private key management and simplified Web2-style authentication. The core principle is that the user, not the application provider, always holds the cryptographic keys to their assets. Social logins (like Google, Apple, or Twitter) are used solely for authentication and key recovery, not for transaction signing. This architecture addresses the significant user experience barrier of seed phrase management while maintaining the self-sovereign security model of Web3. Popular implementations include Account Abstraction (ERC-4337) Smart Accounts and MPC (Multi-Party Computation) wallets.

The security model hinges on separating the authentication layer from the signing layer. When a user signs up via a social login, the backend generates a cryptographic secret share or deploys a smart contract wallet. The critical private key is never stored centrally; it is either distributed via MPC protocols or its control is embedded in a smart account's logic. For recovery, the social provider's OAuth flow can trigger a secure, user-verified process to regenerate or restore access to the wallet, often requiring additional factors like trusted devices or encrypted backups to prevent provider-level account takeover attacks.

Key architectural components include an SSO/OAuth integration for the social login flow, a secure key management service (KMS) for handling secret shares or deployer keys, and on-chain smart contract factories for ERC-4337 accounts. The frontend interacts with these services and standard providers like ethers.js or viem. A critical design decision is choosing between an MPC-based approach (e.g., using tss-lib or a service like Web3Auth) or a Smart Account approach (using bundlers and paymasters via @account-abstraction/sdk). Each has trade-offs in gas costs, interoperability, and complexity.

For development, essential prerequisites include proficiency with a frontend framework (React, Next.js), understanding of OAuth 2.0/OpenID Connect flows, and familiarity with Ethereum tooling. You will need testnet ETH, access to developer accounts for your chosen social platforms, and libraries like @web3auth/core for MPC or @account-abstraction/sdk for ERC-4337. The following sections will guide you through implementing both patterns, from initial auth flow to executing a user-signed transaction, with concrete code examples for key generation, session management, and on-chain operations.

A non-custodial wallet with social logins is a hybrid system that separates user authentication from asset custody. The architecture typically involves three distinct layers: the frontend client (dApp or mobile app), a backend authentication service, and the on-chain smart contracts that manage the wallet's logic and assets. The key innovation is using a user's social identity (like a Google or Twitter account) to generate a cryptographic seed phrase and wallet address, without the service provider ever having access to the private keys. This is achieved through account abstraction and signer delegation patterns.

The core component is the Smart Account, an ERC-4337-compatible contract wallet. Unlike a traditional Externally Owned Account (EOA), a smart account's logic is programmable. It is deployed to a deterministic address derived from the user's social identifier and a global salt. The contract holds the user's assets and executes transactions based on validation rules defined in its code. Crucially, it accepts signatures from a designated Permissioned Signer, which is controlled by the backend authentication service, but only for specific, pre-authorized actions like initial setup and social recovery.

The Authentication & Key Management Service is the trusted backend that bridges Web2 and Web3. It uses OAuth 2.0 to verify a user's social login, then cryptographically derives a Signer Private Key. This key is used to sign transactions on behalf of the user's smart account but is never exposed to the frontend. The service stores this key securely, often using cloud HSM or managed services like AWS KMS. Its primary functions are to sign deployment transactions for new smart accounts and to sign UserOperations (UserOps) for social recovery or gas sponsorship, adhering strictly to the validation rules encoded in the smart account.

The Bundler and Paymaster are critical infrastructure components defined by the ERC-4337 standard. The Bundler packages UserOps from users into a single on-chain transaction, managing gas efficiency and mempool dynamics. The Paymaster allows for gas abstraction, enabling users to pay fees in ERC-20 tokens or enabling the dApp to sponsor transaction costs, removing a major UX hurdle. For a social wallet, the Paymaster is often configured to sponsor the initial account deployment transaction, allowing users to start using the wallet with zero upfront ETH.

Finally, a Social Recovery Module must be integrated into the Smart Account logic. This allows users to designate trusted guardians (other social accounts or wallet addresses) who can collectively approve a request to change the account's signer if the original social login is lost. This module executes via a multi-signature scheme on-chain, ensuring recovery is decentralized and trust-minimized. The architecture's security relies on the separation of concerns: the backend signer has limited powers, asset custody is on-chain, and recovery is socialized.

Traditional non-custodial wallets require users to manage a private key or seed phrase, a significant usability barrier. Social logins (like Google or Apple) solve this by using OAuth for authentication, but they don't provide the cryptographic keys needed for blockchain signing. The core architectural challenge is to create a signing key that is never fully assembled in one place, while allowing a user to recover it using only their social login credentials. This is where Threshold Signature Schemes (TSS) and Multi-Party Computation (MPC) become essential. They enable the generation and use of a private key that is split into multiple secret shares.

The architecture relies on a distributed key generation (DKG) protocol. During wallet setup, two or more parties collaboratively generate a public/private key pair without any single party ever learning the complete private key. In a social login context, one secret share is stored client-side (e.g., encrypted on the user's device), and another is held by a network of servers or a trusted execution environment (TEE). The user authenticates via their social provider, which grants access to the server-side share. The actual signing process uses MPC protocols like GG18 or GG20, where the client and server compute a signature together, with each using their share, without reconstructing the full key.

For developers, implementing this requires choosing an MPC/TSS library. LibTSS, ZenGo's Multi-Party-ECDSA, and Coinbase's Kryptology are popular open-source options. A typical flow involves: 1) User logs in with OAuth, 2) Server verifies the OAuth token and retrieves the user's encrypted server share, 3) Client requests a signature for a transaction, 4) Client and server engage in an MPC signing round, exchanging messages, 5) A valid ECDSA signature is produced and broadcast to the network. The client-side code handles the MPC protocol logic and local share management, often using WebAssembly (WASM) modules for performance and security.

Key security considerations include the trust model for the server-side share provider and key refresh protocols. To mitigate the risk of a compromised server, shares can be periodically refreshed (re-shared) without changing the public address, a process known as proactive secret sharing. Furthermore, the architecture should support account abstraction patterns, allowing the MPC-generated key to be the owner of a smart contract wallet (like an ERC-4337 account) for enhanced functionality. Auditing the MPC implementation is critical, as subtle bugs can lead to key leakage.

This architecture provides a superior user experience comparable to Web2 apps while maintaining non-custodial security. Users retain ultimate control—if the social login provider or server-side infrastructure disappears, the client-side share combined with a backup method (like cloud-stored encrypted shards or secondary guardians) can recover the wallet. Projects like Web3Auth, Privy, and Dynamic offer SDKs that abstract this complex MPC layer, allowing developers to integrate social logins with non-custodial wallets in hours rather than months.

Traditional non-custodial wallets require users to securely store a 12-24 word seed phrase, a significant usability and security hurdle. Social logins (like Sign in with Google or Apple) solve the onboarding problem but typically rely on centralized custodians. The architectural challenge is to use a social login as a recovery mechanism while keeping the cryptographic keys that control assets under the user's sole control, stored locally on their device. This is achieved by splitting the process into two distinct phases: key generation and secure storage on the device, and a separate, encrypted backup for recovery.

The core of this architecture is the device's Secure Enclave (on iOS/macOS) or Trusted Platform Module (TPM) (on Windows/Android). These are hardware-isolated coprocessors designed to generate and store cryptographic keys. When a user creates a new wallet, your application instructs the Secure Enclave/TPM to generate a new asymmetric key pair (e.g., using the secp256k1 or Ed25519 curve). The private key never leaves the secure hardware; only the public key is exposed to the application. All signing operations for transactions are performed inside the enclave, with the application only receiving the signature. This provides hardware-grade security for the primary key.

For recovery, you cannot extract the private key from the Secure Enclave. Instead, the architecture uses a social login to encrypt a backup. During setup, the app generates a strong, random secret (e.g., a 256-bit symmetric key). This secret is used to encrypt a backup package containing the wallet's public address and metadata. The encrypted backup is then sent to a backend service, but the encryption key itself is sent to the social login provider's key custody service (like Google's Secure Key Store or Apple's iCloud Keychain) via protocols like WebAuthn or Credential Manager API. To recover, the user logs in, retrieves the encryption key from the social provider, fetches the encrypted backup from your server, and decrypts it to initialize a new Secure Enclave key-pair mapping.

Implementing this requires platform-specific APIs. For iOS, you use the LocalAuthentication and Security frameworks to interact with the Secure Enclave via SecKeyCreateRandomKey with the .privateKeyUsage attribute. For Android with TPM/StrongBox, you use the KeyStore class with KeyGenParameterSpec.Builder and setIsStrongBoxBacked(true). The WebAuthn flow for key backup involves calling navigator.credentials.create() to register a public key credential with the relying party (your backend). Your smart contracts or wallet logic must also be designed to allow key rotation, as the Secure Enclave key on a new device will be different, but it should control the same on-chain identity or account abstracted wallet.

Key management services like Web3Auth, Dynamic, or Privy abstract much of this complexity. They provide SDKs that handle the cross-platform Secure Enclave/TPM interaction, the WebAuthn ceremony with social logins, and the encrypted backup network. However, understanding the underlying architecture is crucial for evaluating security trade-offs. The critical trust assumption shifts from the social provider holding your assets to them holding an encryption key for your backup. The assets remain non-custodial, as the social provider cannot sign transactions without access to the user's specific physical device holding the primary key.

This pattern is foundational for account abstraction (ERC-4337) wallets. The key in the Secure Enclave can act as the signing key for a smart contract wallet. Social recovery can be implemented by using the recovered backup to authorize a smart contract operation that changes the entry point's signing authority to a new key generated on the user's new device. This creates a seamless user experience where account recovery feels like a simple social login, while maintaining the security and self-custody properties of a hardware-backed private key.

A non-custodial wallet with social logins uses Decentralized Identifiers (DIDs) as its core identity layer, replacing traditional seed phrases. A DID is a globally unique, cryptographically verifiable identifier (e.g., did:key:z6Mk...) controlled by the user. When a user logs in via a platform like Google or GitHub, the wallet creates a Verifiable Credential (VC)—a signed attestation from that platform. This VC, which might state "Google attests that alice@gmail.com controls this DID," is stored in the user's wallet, not on a central server. This architecture separates the proof of identity (the social login) from the control of identity (the DID and private keys).

The technical flow involves three main components: the Wallet App, an Identity Provider (IdP) like Google, and a Resolver for the DID method (e.g., did:key or did:web). The wallet generates a DID and its corresponding cryptographic keys locally. It then initiates an OAuth flow with the IdP. Upon successful authentication, the wallet requests a signed VC from the IdP's attestation service. This VC uses a standard data model like the W3C Verifiable Credentials Data Model and is cryptographically bound to the user's newly generated DID.

For developers, implementing this requires a library for DID and VC operations, such as did-jwt-vc for Ethereum or @digitalbazaar/ed25519-verification-key-2020 for key-based DIDs. The core wallet function involves creating a DID document and managing the private key securely (e.g., in localStorage or a secure enclave). The code snippet below shows a simplified VC issuance request after OAuth:

javascriptCopy
const vcPayload = {
  "@context": ["https://www.w3.org/2018/credentials/v1"],
  "type": ["VerifiableCredential", "SocialLoginCredential"],
  "issuer": "https://accounts.google.com",
  "credentialSubject": {
    "id": userDID, // The user's DID
    "email": "alice@gmail.com"
  }
};
// The IdP signs this payload and returns the VC

User key management is critical. The private key for the DID must never leave the user's device. Social login serves only as a recoverable authentication factor. If a user loses their device, recovery can be facilitated through the IdP by re-authenticating and issuing a new VC to a new DID/key pair, or by using a more advanced social recovery scheme where trusted contacts (guardians) hold shards of an encrypted backup. This maintains non-custodial principles while improving usability.

This architecture has significant implications. It reduces onboarding friction, as users don't need to write down a seed phrase initially. It also enables selective disclosure; a user can prove they own a Google-verified email without revealing the email itself, by presenting a zero-knowledge proof derived from the VC. However, developers must consider vendor lock-in—the wallet should support multiple IdPs and allow users to migrate their DIDs. Frameworks like Veramo and SSI-SDK provide pluggable modules for managing multiple DID methods, VCs, and storage backends, forming a robust foundation for production wallets.

The core challenge is decoupling authentication from authorization. A social login (e.g., Google OAuth, Sign in with Apple) proves who you are but must not control what you own. The standard architecture uses a signer service or key derivation service as a trusted intermediary. When a user authenticates via their social provider, this service generates or retrieves a cryptographic key pair (like an Ethereum EOA) on their behalf. Crucially, the service only returns a signed user operation or transaction to the client; the private key never leaves the secure server environment. This model, used by services like Privy and Dynamic, shifts the custody of the signing key to a third party, which must be explicitly trusted.

For enhanced security and reduced trust, implement multi-party computation (MPC) or threshold signature schemes (TSS). Here, the social login triggers the generation of key shares distributed between the user's device and the service provider. A single share is useless; signing requires collaboration. For example, the service could hold one share and encrypt another with the user's OAuth id_token for client-side recovery. This eliminates a single point of failure. Protocols like Web3Auth and Turnkey use TSS to ensure no single entity—not even the service provider—has full control of the private key, significantly improving the security model versus a simple signer service.

Smart contract wallets, or account abstraction (ERC-4337), offer the most robust architecture. The social login becomes the guardian for a smart contract account. The signer service acts as a social recovery module or session key granter. For instance, after social login, the service can sign a user operation to deploy a smart account (like a Safe or SimpleAccount) and program it with recovery logic. Future transactions can use limited session keys authorized by the social login, while the account's ultimate ownership is secured by multiple guardians. This keeps assets self-custodied in an immutable contract, with social login serving as a convenient, revocable access method.

Auditing this architecture requires scrutinizing several critical paths. First, audit the key generation and storage of the signer service or MPC nodes. Are keys generated in a secure enclave (e.g., AWS Nitro, GCP Confidential VM)? Is key material ever exposed in logs or memory? Second, review the social login integration flow for OAuth vulnerabilities like CSRF, state parameter leaks, or insecure redirects. Third, for smart accounts, verify the account initialization and recovery logic is free from access control flaws. Finally, assess the client-side SDK for integrity—ensuring it communicates with the genuine service and correctly handles authorization tokens. A comprehensive audit should treat the signer service as a Hardware Security Module (HSM) equivalent.

Developers must also plan for user lifecycle events. What happens if a user loses access to their social account? A robust system requires fallback recovery methods, such as email-based one-time codes or a set of backup guardians. Furthermore, consider compliance and data privacy; using social logins may introduce GDPR or COPPA considerations regarding personal identifiable information (PII). Always disclose the trust model: users must understand they are trusting the service provider's infrastructure for key management, even in MPC or smart account setups. The code, audit reports, and security assumptions should be fully transparent.

You have now implemented the foundational architecture for a non-custodial wallet with social logins. This combines the user experience of Web2 with the security model of Web3. The key components are the embedded MPC wallet (e.g., Privy, Web3Auth) for key management, a social login provider (e.g., Google OAuth, Sign in with Apple) for authentication, and a smart account abstraction standard like ERC-4337 for transaction bundling and gas sponsorship. The user's private key is never exposed to your application server, maintaining non-custodial security.

For production deployment, several critical steps remain. Security auditing of your smart contracts and integration code is non-negotiable. Implement robust key rotation policies and session management. You must also design a clear recovery flow for users who lose access to their social account. Consider using multi-factor authentication (MFA) add-ons from your MPC provider or implementing transaction simulation services like Tenderly or Blowfish to protect users from malicious transactions before they sign.

To extend your wallet's functionality, explore integrating account abstraction features. Use paymasters to allow gasless transactions for your users, sponsored by your application or a third party. Implement batch transactions so a single user signature can execute multiple actions, like swapping tokens and providing liquidity in one click. You can also add social recovery modules where trusted friends or devices can help restore account access, moving beyond a single social login dependency.

The final step is choosing your blockchain networks. Start with Ethereum Mainnet and Polygon PoS for broad coverage, then add Optimism, Arbitrum, or Base for low-cost L2 transactions. Use a service like Chainlist or the WalletConnect Cloud to manage chain metadata. Remember, each added chain increases the complexity of state management and RPC calls, so prioritize based on your target users. Your wallet is now ready to serve as the gateway to your onchain application.