Passphrase and MPC Key
This section explains the key security concepts and procedures related to passphrases and MPC keys within TSI. Understanding these concepts is crucial for securely managing your digital assets on the platform.
MPC Key Shares and Transaction Signing
TSI utilizes Fireblocks' 2-of-2 Multi-Party Computation (MPC) scheme to enhance the security of digital signatures. This means that two key shares are required to sign any transaction:
Key Share #1: This key share is securely held and managed by Fireblocks within a secure enclave.
Key Share #2: This key share is generated by the user (trader/liquidator) or organization admin through Fireblocks' SDK and securely stored within their device's browser.
When a transaction is initiated, the user signs first using their key share (#2). Fireblocks then co-signs the transaction using its key share (#1). This two-step process ensures that no single party can unilaterally authorize a transaction, significantly reducing the risk of unauthorized access or fraud.
Encrypted Key Share and Passphrase
Encrypted Storage: The user's MPC key share (#2) is encrypted and stored in two locations:
The user's browser local storage on the associated device.
The Fireblocks server.
Decryption with Passphrase: To use the encrypted key share for signing transactions, it needs to be decrypted using the user's unique passphrase. This passphrase is never transmitted over the network and is only stored in the user's local browser storage and any backups the user may have created.
Local Decryption: When signing a transaction, the decryption process happens entirely within the user's local browser. This ensures that the passphrase is not exposed outside the user's device and browser, enhancing security.
Passphrase Security and Responsibility
User Responsibility: Users are solely responsible for securely storing and managing their passphrase. TSI ensures that the passphrase is never exposed outside the user's local environment.
Irrecoverable: If a user loses their passphrase, neither Fireblocks nor TSI can recover it. This means the assets in the associated wallets will be locked and irrecoverable. Users must take full responsibility for preserving their passphrase.
MPC Key Generation and Management
Initial Generation: When an organization admin is invited to join TSI, they must generate their MPC key and passphrase. This MPC key contains both an ECDSA key and an EdDSA key, used for signing transactions on EVM and non-EVM chains, respectively. The admin is then prompted to download a JSON file containing their encrypted key share, passphrase information, and a key ID. This file should be stored securely as a backup.
Device and Browser Binding: Once generated, the MPC key is bound to the specific browser and device used during the creation process. If a user wants to access TSI from a different browser or device, they need to recover their MPC key using the downloaded JSON file.
Key Limits: Each organization account can have a maximum of 10 MPC keys generated, a limitation imposed by Fireblocks' Embedded Wallet.
User Invitation and Activation: When an organization admin invites a user, the user must also generate their MPC key. The user then sends a code to the admin for approval, activating the key. This process ensures secure key generation and activation.
Wallet Association and Usage
Wallet-User Association: Organization admins can associate specific wallets with different users.
Transaction Signing: A user's MPC key can sign transactions and transfer assets from the wallets associated with their account.
By understanding these key aspects of passphrase and MPC key management, TSI users can confidently and securely manage their digital assets on the platform.
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