OmniSafe utilizes both multi-signature wallets and Threshold Signature Schemes (TSS) to distribute signing authority and enhance security. These technologies ensure that no single point of failure can compromise your assets.

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Multi-Signature Wallets: Shared Control for Enhanced Security

Multi-signature (MultiSig) wallets provide a foundational layer of enhanced security by requiring multiple approvals for any transaction. Instead of a single private key controlling a wallet, a MultiSig wallet mandates that a threshold number of authorized parties must sign a transaction before it can be executed. This is analogous to requiring multiple signatures on a check or multiple keys to open a safe.

Each MultiSig wallet is configured with n authorized signers and a threshold t (where t ≤ n). A transaction requires at least t valid signatures to be considered valid and executed. These signers use independent generation of their unique keys that are non-shared with other users. In order to send a transaction, the following steps need to be followed:

  1. A user (or an automated process) initiates a transaction, specifying details like the recipient address and the amount. This transaction request is presented to each of the n authorized signers.
  2. Signers who approve the transaction use their unique private key to generate a digital signature specific to that transaction, using ECDSA (Elliptic Curve Digital Signature Algorithm).
  3. Once the threshold of t signatures is collected, the transaction is ready for submission to the blockchain.

The MultiSig contract in OmniSafe validates the submitted signatures against the public keys associated with each signer, enforcing the t-of-n rule.

A multisig transaction requires using smart contracts, so we have:

Signature Storage (Solidity) in the multisig contract.

  • the contract stores details like ‘v,r,s.’
  • Retrieval is easy, as every wallet member can sign the details using ecrecover.
  • Verifying is performed by the verifySignature function that validates the signature.

Only if the signatures are valid and meet the threshold requirement will the contract execute the transaction.

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Threshold Signature Scheme (TSS): Advanced Security Through Distributed Key Management

Going beyond MultiSig, OmniSafe offers Threshold Signature Schemes (TSS) as an advanced cryptographic approach for distributing signing authority. TSS takes security a step further: instead of each signer holding a separate private key, it splits a single private key into multiple shares. No single party holds the complete key, and a threshold number of shares must be combined to create a valid signature.

Key Splitting & Distribution:

  1. The private key is split into n shares using cryptographic techniques like Shamir’s Secret Sharing (SSS), as discussed previously.
  2. A threshold t (where t ≤ n) is defined, representing the minimum number of shares required to sign a transaction.
  3. These shares are distributed among independent parties or devices. Each party securely stores their share.

Distributed Signing Process:

  1. When a transaction needs to be signed, a secure multi-party computation (MPC) protocol is initiated among the participating parties.
  2. Each party uses their individual key share as input to the MPC protocol, along with a random number.
  3. The MPC protocol allows these parties to collaboratively generate a digital signature that is valid under the original public key corresponding to the split private key.
  4. Importantly, the private key itself is never reconstructed during this process, ensuring that it remains protected at all times. This removes the risk of human involvement and is a mathematical procedure.

Security Benefits:

  • No Single Point of Failure: At no point does a single entity possess the entire private key. An attacker must compromise at least t shares to create a valid signature.
  • Robustness in Adverse Conditions: Even if some participants are offline or compromised, as long as the threshold t is met, the system can still generate valid signatures.
  • Forward Secrecy: By rotating key shares periodically, even if an attacker compromises shares at one point in time, they cannot use these shares to sign transactions indefinitely.
Cold vs Hot StorageGeneral Security Components