# Technical Documentation

ether.fi is launching **ether.fi Cash**, an advanced DeFi payment solution designed for crypto users, developers, and institutional investors seeking a secure, non-custodial financial experience.

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## 1. Secure and Non-Custodial _Vault_

Upon creating an account at ether.fi Cash, a dedicated smart contract, [_**ether.fi Vault**_](vault)_**,**_ is automatically deployed for you. This Vault ensures **secure and non-custodial** control, meaning you remain the exclusive owner of your funds, maintaining complete autonomy.

**Diagram 1: Vault Ownership/Authentication Architecture**

<figure><img src="https://1029745181-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FG3Lk76lfvw9ecPIg0mK8%2Fuploads%2FeyBXLcuDUouD2RN3PDXe%2Fimage.png?alt=media&#x26;token=ad1f53df-1c73-485f-a0c8-89f583880495" alt=""><figcaption></figcaption></figure>

### Security as a First-Class Citizen

Your Vault is secured by sophisticated cryptographic management through a secure enclave architecture (i.e., [Trusted Execution Environment](https://en.wikipedia.org/wiki/Trusted_execution_environment)) provided by [Turnkey](https://www.turnkey.com/). This secure enclave generates and manages your keys, significantly enhancing security compared to traditional wallets reliant on seed phrases. The keys remain encrypted and inaccessible outside this secure environment, accessible only via explicit, user-authorized cryptographic authentication.

The enclave-based security design ensures robust protection against both external threats and internal risks, providing a tamper-proof environment where even ether.fi or Turnkey cannot access your private keys, thereby reinforcing the non-custodial nature of your wallet.

### Non-Custodial by Design

ether.fi Vault is designed to be entirely user-owned and controlled. Your encrypted keys are strictly managed within the Secure Enclave, accessible exclusively through user-authorized cryptographic authentication. It guarantees that neither ether.fi nor any third-party can ever access or control your Vault or your keys.

### Seamless DeFi Banking Experience

ether.fi seamlessly integrates its advanced DeFi primitives, such as [Staking](../staking) and [Liquid](../liquid) products, to deliver a premium, frictionless DeFi banking experience. This integration ensures you have effortless access to the top-class decentralized finance products directly within your Vault.

Moreover, ether.fi enables secure direct card spending linked to your Vault, allowing users flexibility between Direct Spend Mode (immediate fund deductions) and Borrow Mode (automatic short-term borrowing). The daily and monthly spending limits are user-configurable, providing an additional layer of security to protect against unauthorized or excessive transactions.

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## 2. Effortless Cross-chain via Universal Address

ether.fi provides a effortless cross-chain deposit service with universal addressing exploiting deterministic address deployment. Users can deposit the supported assets to their vault at any supported EVM chain from any address (e.g., personal wallet, or crypto exchange).

**Diagram 2: Cross-Chain Operation via Universal Address**

<figure><img src="https://1029745181-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FG3Lk76lfvw9ecPIg0mK8%2Fuploads%2FQXiKM5DLPtYGkPRMy9Vy%2Fimage.png?alt=media&#x26;token=9d911adc-e2b0-4428-b1e9-7b5bd3828c59" alt=""><figcaption></figcaption></figure>

### Universal Vault Address

Through advanced deterministic deployment (using Create3), each user is assigned a universally consistent address across all EVM-compatible blockchains. The address is used for the dedicated Vault contract on Scroll and for the deposit address on other chains. That is, users can deposit to their vault at any supported EVM chain from any address (e.g., personal wallet, or crypto exchange).

The unique address is assigned to each user can be extended for chain-agnostic smart wallet system in future! Stay tuned!

### Near-Instant, Automated, and Transparent Bridging

Funds sent to your unique address on any supported blockchain are swiftly and transparently bridged to your dedicated Vault on Scroll. This process leverages automated & secured smart contract interactions ensuring a superior user experience without cumbersome manual steps.

### Handling Unsupported Assets

Currently, only assets explicitly supported within the ether.fi ecosystem can be deposited securely. Depositing unsupported assets may result in funds becoming inaccessible. Proper handling, including withdrawal support for these assets, will be introduced in a future upgrade.

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## 3. Modular Design for Security

ether.fi’s Vault contract adopts modular design, delivering both security and flexibility for DeFi banking experiences. This modular architecture enables managed, secure operations through distinct, independently managed modules.

### Modular Contract Framework

At its core, the Vault contract serves strictly as a robust multisig authorization and module management hub. Direct interactions with the Vault are securely restricted, ensuring all functionalities are executed exclusively via thoroughly vetted modules.

### Module Governance

Modules are individually whitelisted and vetted by ether.fi, designed as non-upgradeable to ensure predictable and stable operations. Each module—such as token management, lending integrations (e.g., Aave), or borrowing—is optimized to perform clearly defined roles, ensuring clean separation of concerns and operational security. The Vault owner needs to approve individual modules to allow the interactions.

### Advanced Hook System for Security

Operational hooks reinforce system health, providing additional security layers. These hooks rigorously validate critical metrics, including debt positions, ensuring robust, continuous integrity monitoring and risk mitigation.

### Role-Based Access Control

Clear role separation between Owners and Admins provide precise control and secure management. Highly sensitive actions, including administrative changes or fund withdrawals, are tightly restricted to Owner-level authorization, adding a vital layer of governance and security.

For more details, visit [here](vault)

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