Email login and self-custody
Sign in with your email, but keep the keys. How modern wallets remove the seed-phrase barrier without quietly taking custody of your funds.
Historically, self-custody meant managing a twelve- or twenty-four-word seed phrase — intimidating for beginners and a real loss risk. Email login combined with self-custody resolves that tension: you sign in with something familiar, your email, but the private keys stay under your control, without Cypay taking custody of your funds.
This is typically implemented with one of two approaches, or a combination of both.
Multi-Party Computation (MPC)
With MPC, the private key never exists as a whole anywhere. It is mathematically split into shares — for example, one on your device, one protected by a service, and one derived from your login. To sign a transaction, the shares collaborate without ever reconstructing the full key in a single place. No single party — not even Cypay — can move your funds alone.
Account Abstraction (ERC-4337)
With Account Abstraction, using the ERC-4337 standard, your wallet is a smart contract. Email login acts as an authorization method — through passkeys, social authentication, or cryptographic proofs — and the contract enforces the rules of who may sign. This enables features like social recovery, session keys, and gas sponsorship.
The key point
Email is the access method, not the owner of the keys. Authentication only unlocks your ability to sign; it does not transfer custody to the platform. You keep sovereignty over your assets — the hallmark of self-custody — with an experience close to a traditional app.
It's also worth understanding the recovery model: how you regain access if you lose your device, and what happens if the login provider goes down. Good systems offer backup and recovery that doesn't reintroduce a single custodial point of failure.
Why it matters. The seed phrase was the single biggest barrier between ordinary people and self-custody — and the single biggest cause of catastrophic, irreversible loss. Removing it without handing the keys to a company is one of the most important usability breakthroughs in crypto: it's what lets self-custody feel like signing into an app while staying genuinely yours.