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What is a Seedphrase?

A seedphrase (also called a recovery phrase or mnemonic phrase) is a group of simple words that stores everything needed to recover a cryptocurrency wallet.

When you create a crypto wallet (like for Bitcoin or Ethereum), your wallet generates a seedphrase — usually 12 or 24 random words. This phrase is the master key to your wallet. If you ever lose access to your device or wallet app, you can use the seedphrase to recover everything: your funds, addresses, and private keys.

What Does a Seedphrase Look Like?

A seedphrase typically contains 12 or 24 words. Here’s an example of a 24-word seedphrase:

Example Seedphrase

squirrel saddle cradle unaware kiwi ketchup confirm yellow horse smoke lumber invite arrow cactus zoo embody round stumble lens donkey network exile arch diesel matrix

–> Do not use this seedphrase as it is not secure!

Each word is chosen from a specific list of 2048 common English words. The order of the words must be exact — changing a single word or even the position of one can render the phrase useless or lead to a completely different wallet.

Human-Friendly, But Secure

Even though the seedphrase is a set of readable words, its true form is a long string of bits chosen from an astronomically large number of possibilities. A 24-word seedphrase offers approximately 256 bits of entropy, far beyond what’s considered breakable with modern technology.

How a Seedphrase Works

Seedphrases are part of a standard called BIP-39 (Bitcoin Improvement Proposal 39). Here’s a simplified breakdown of what happens behind the scenes:

  1. Entropy → Mnemonic Phrase The wallet starts by generating a large, random number called entropy. This entropy is converted into a list of words using the BIP-39 word list and checksum rules. This list of words is your seedphrase.

  2. Mnemonic Phrase → Seed The seedphrase is run through a process called PBKDF2 hashing to produce a binary seed. This seed is what wallets use to create private keys

  3. Seed → Keys & Addresses The seed is used to generate a hierarchical set of private keys and addresses using another standard called BIP-32 or BIP-44 This means that from one seedphrase, your wallet can generate a practically unlimited number of crypto addresses.

Because of this setup, your seedphrase is all you need to recreate your wallet and access your funds.

Optional Passphrase

When using BIP-39 wallets, you can optionally add a passphrase (sometimes called a 25th word) on top of your seedphrase. This works like a second password.

  • Your seedphrase stays the same, but the wallet adds the extra passphrase into the seed generation process.
  • Using a different passphrase will result in a completely different wallet, even with the same seedphrase.
  • If you lose or forget this optional passphrase, you cannot recover the wallet.

This feature can improve security, especially if you are worried about someone stealing your seedphrase. However, it adds complexity and risk if not managed properly.

For more details, check out these sections: