Deciphr Academy
Track 2 · Keeping crypto safe · Module 9

Multisig and smart accounts

Wallets that need several people to approve: the standard for company treasuries.

Lessons
6
Reading
42 min
Quiz
15 questions
Pass mark
80%
  1. 1What 2-of-3 meansWhat is a multisig wallet, and what does 2-of-3 mean?6 min
  2. 2How a Safe worksHow does a Safe multisig account work?7 min
  3. 3Choosing signers and thresholdsHow do you choose the signers and threshold for a multisig?7 min
  4. 4MPC vs multisigWhat is the difference between an MPC wallet and a multisig?7 min
  5. 5Smart accounts (ERC-4337)What are smart accounts, and what do ERC-4337 and EIP-7702 change?7 min
  6. 6Running treasury approvalsHow should a team run multisig approvals for a company treasury?8 min

The case used in this module

Each module tells its own made-up Brindlecove story, so details can differ from one module to the next.

Key words

Multisig
Short for multi-signature. On Ethereum, a smart contract account that needs a set number of valid signatures, out of a group of keys, before it acts.1
Threshold
The least number of owners who must confirm a transaction before a multisig such as a Safe will carry it out.2
Smart account
An account controlled by smart contract code rather than by one private key. Its code decides who can move funds, and how.3
Safe module
An add-on contract that gives a Safe extra features, such as a daily spending allowance. It can skip the signature check, so a bad one can take over a Safe.42
Delegate call
A call that runs another contract's code as if it were the calling contract's own. Safe's help centre calls it dangerous in an ordinary transaction.56
MPC (secure multiparty computation)
A way for several parties to work out a result together without showing each other their secret inputs, such as shares of a key.78
Threshold signature
One ordinary-looking signature made by enough holders of a shared key. It is checked against a single public key.9
Account abstraction
Letting each account set its own rules for checking transactions, written as smart contract code.10
Bundler
Under ERC-4337, a node that collects UserOperations and packs them into one real transaction.10
Paymaster
Under ERC-4337, a helper contract that agrees to pay a transaction's fee instead of the user.10
EIP-7702
A 2025 change that lets an ordinary account point to smart contract code. The account's private key still keeps full control.1112
Separation of duty
The security principle that no one person should have enough power to misuse a system on their own.13
Sources
  1. Introduction to smart contracts (multisig contracts). ethereum.org developer docs, page updated 25 February 2026.
  2. Concepts: owners, threshold, signature verification and transaction flow. Safe documentation.
  3. How do Safe Smart Accounts work?. Safe documentation (Safe Smart Account overview).
  4. Safe Modules. Safe documentation.
  5. Sygnia's Investigation into the Bybit Hack: What We Know So Far. Sygnia (a security firm that examined the Bybit signers' computers), 16 March 2025.
  6. How to perform basic transactions checks on Safe{Wallet}. Safe Help Center (Safe Knowledge Base).
  7. Multi-Party Threshold Cryptography (MPTC) project. US National Institute of Standards and Technology (NIST), Computer Security Resource Center.
  8. NISTIR 8214: Threshold Schemes for Cryptographic Primitives. L. Brandão, N. Mouha and A. Vassilev, US National Institute of Standards and Technology (NIST), March 2019.
  9. Threshold signature. Bitcoin Optech (topics).
  10. ERC-4337: Account Abstraction Using Alt Mempool. Ethereum Improvement Proposals (V. Buterin, Y. Weiss, D. Tirosh and others), created 29 September 2021; status Final.
  11. The history of Ethereum (now titled Ethereum forks). ethereum.org, page updated 26 June 2026.
  12. Pectra EIP-7702 guidelines. ethereum.org roadmap, page updated 17 July 2026.
  13. Glossary: separation of duty (from NIST SP 800-192). US National Institute of Standards and Technology (NIST), Computer Security Resource Center.