Recovery words / Seed Phrase
Everything you need to know about seed phrases and recovery words — your Bitcoin key to the future.
Recovery words, or a "seed phrase", are a series of words that generate a private key and are typically used as a backup. BIP39 is a standard for generating these recovery words and is used to generate and back up cryptographic keys. The standard defines a method for converting a random sequence of bytes into a list of easily memorable words, also called a mnemonic seed phrase. A typical BIP39 mnemonic phrase consists of 12, 15, 18, 21, or 24 words, with 12 or 24 words being the most common.
How it works
- Random sequence: A random sequence of bytes (entropy) is generated first.
- Checksum: A checksum is calculated using a hash function (SHA-256) and added to the entropy.
- Splitting: The combined bit string is divided into groups of 11 bits, each representing a number.
- Word list: These numbers are used as indexes to look up a predefined list of 2048 words.
- Mnemonic phrase: The corresponding words form the mnemonic phrase.
The mnemonic phrase can then be used to generate a BIP32 master key and associated keys and addresses. This standard provides a secure and more user-friendly way to back up and restore a bitcoin wallet, since it's far easier to handle, say, 12 words in the correct order than to handle a BIP32 master key.
Examples
BIP32 master key example:
xprv9s21ZrQH143K2eyxu8x6wruSnz58hnRo2or4zZhVmAAHqMr6DqcJaAkeN91t2tWWaRX7YXoaxfSQD7arvnj3dhR3v45KM78mveNY3w8C3Q6 BIP39 mnemonic seed example:
aacff76633d33040b70eff19108925364cd39dffd98ea510402d50ba28e28cff2bcf6c0a39505b8d11a71da707d27273320af600802526830f626e6e9480a5cf BIP39 mnemonic word example:
bonus, oxygen, borrow, private, sight, income, panic, ethics, play, piano, wedding, edit Quick summary
Mnemonic: A user-friendly sequence of words that represents a private key in an easily understandable way.
Seed: A binary string derived from the mnemonic phrase, used to generate hierarchical deterministic keys.
Generating recovery words
All of the information shown in the examples is critical to the security of your bitcoin, and it's very important that no one else gains access to any of it. For that reason, this information should never come into contact with devices that have internet access. By generating your recovery words with a bitcoin wallet / hardware wallet built specifically for that purpose, you achieve good security.
Storing recovery words
As mentioned, it's very important that this information is stored securely — which also means you shouldn't write it down on your phone or computer, and so on. You can write your recovery words on one — or several — pieces of paper, perhaps kept in a "tamper-evident bag" in a safe place. Paper isn't the preferred solution, though, since it can easily be destroyed by flooding, fire, and the like, so it's recommended to secure this information on steel or titanium.
Tinyseed
A great solution is Tinyseed, a small titanium plate that can withstand most conceivable destruction scenarios. You can read a review of Tinyseed here: Tinyseed review by Jameson Lopp
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