how does metamask generate private key

During MetaMask setup, users generate a seed phrase that converts into entropy, ultimately used to deterministically derive private keys for multiple accounts via a master key generated using HMAC-SHA3.

Nov 05, 2024 at 02:52 pm

How MetaMask Generates Private Keys

Step 1: User Input a Seed Phrase

Users create a seed phrase, a series of 12 or 24 random words, during the initial setup of MetaMask. This seed phrase acts as a master key to generate all Ethereum addresses and corresponding private keys.

Step 2: Convert Seed Phrase to Entropy

The seed phrase is converted into a form of randomness known as entropy using a deterministic algorithm called PBKDF2 (Password-Based Key Derivation Function 2). This process involves hashing the seed phrase multiple times with a salt (a randomly generated value) to ensure the entropy is unique and secure.

Step 3: Use Entropy to Generate Master Key

The entropy is used to derive the master key, a 256-bit cryptographic key, using a cryptographic primitive called HMAC-SHA3. This key serves as the root for generating all private keys and addresses within MetaMask.

Step 4: Deterministically Generate Private Keys

For each account created in MetaMask, the master key is used to generate a new private key using a deterministic formula. This process ensures that the private key is pseudorandom and unique for each account, preventing users from accidentally generating duplicate keys.

Step 5: Convert Private Key to Public Key

The private key is then used to derive the corresponding public key using the elliptic curve cryptography algorithm, secp256k1. This public key is used to generate Ethereum addresses that receive and send cryptocurrency.

Security Considerations

• The security of MetaMask's private key generation relies heavily on the strength of the seed phrase.
• Users must keep their seed phrase secret and secure, as it can be used to compromise all their accounts.
• MetaMask does not store private keys on its servers, providing users with full control and responsibility over their funds.