How to Create a Secure Seed Phrase for Crypto
how to create a secure seed phrase
To create a secure seed phrase, you should let a cold storage wallet generate it or use physical randomness like rolling dice. Avoid making up your own words because human generated phrases are easy to crack.
You can add a passphrase to your seed phrase to create an extra layer of protection known as a hidden wallet. Keep your passphrase in a password manager while keeping your main 12 to 24 seed words entirely offline, making sure the two are never stored in the same place.
Write your verified seed words on durable metal plates rather than standard paper. Keep multiple copies of these plates in separate geographic locations to protect your funds from localized disasters.
Security methods
- Cold storage wallet Lets the hardware generate the seed phrase for you to ensure proper randomness.
- Physical dice Roll 100 six sided dice, convert the string to SHA256, and compute the checksum for 264 bits.
- Air gapped computer Use a live operating system completely disconnected from the internet to prevent malware interference.
- Metal plates Store your words on fireproof and waterproof metal instead of paper to avoid physical degradation.
- Shamir Secret Sharing Splits your seed into sets, such as three sets of 20 words that require two of the three to reconstruct.
- Passphrase Acts as a 25th word to create a hidden wallet and should be kept in a separate location like a password manager.
Generate Your Seed Phrase Securely
Avoid self-created seed phrases: Relying on your own "randomness" or using memorable phrases makes them easier to crack. "Don't do it yourself, let a cold storage wallet or wallet generate the seed phrase for you".
Utilize physical randomness for generation: For those not trusting hardware wallets, manual methods like rolling dice and converting the results into a seed phrase offer a high degree of entropy. "Why not dice? Roll 100 D6, write the string down, do SHA256, compute checksum and append to hash, get 264 bits.".
Use air-gapped systems for digital generation: If using software to generate, do so on a machine completely disconnected from the internet and ideally using a live operating system to prevent malware interference. "It seems obvious to me that the best way to do anything in this space is by relying not on small, commercial operators but extremely large and old communities that are well-audited.".
Implement Passphrases for Added Security
Add a passphrase to your seed phrase: A passphrase acts as a 25th word, creating a "hidden wallet" that requires both the seed and the passphrase to access funds. "The only option is to use the air gapped flux capacitor entropy on a seed phrase dungeons and dragon dice that were created by naked virgin nuns… duhhh".
Store passphrases separately from seed phrases: Never keep your passphrase in the same location as your written seed words. "Passphrases can be stored in password managers like normal humans. Having a passphrase in a password manager and the seed phrase offline is the best of both worlds.".
Choose strong, random passphrases: Avoid using dictionary words, personal details, or phrases from common literature, and ideally use random words to maximize security. "Make sure the passphrase seed extension is also written down somewhere private so you do not forget it! Do not keep the passphrase in the same location as your 12-24 seed backup words.".
Physical Storage and Redundancy
Use durable physical backups: Materials like metal plates are recommended over paper as they are fireproof, waterproof, and more resistant to degradation. "Stopped using paper. Got a metal seed phrase backup plate ($30-50). Fireproof, waterproof, basically indestructible. Keep this in your primary location.".
Distribute copies geographically: Store multiple copies of your seed phrase (and passphrase, if applicable) in different secure locations to protect against localized disasters. "Keep it in 2 metal plates in different places.".
Consider Shamir's Secret Sharing or multisig: For high-value assets, advanced methods like Shamir's Secret Sharing (requiring a certain number of parts to reconstruct the seed) or multi-signature wallets can provide enhanced security and fault tolerance. "A correctly set up Shamir secret sharing seed will be 3 sets of 20 words that require 2 of 3.".
Do you have concerns about securing your seed phrase against specific types of threats?
Bottom line
Using a passphrase alongside a physically stored seed phrase is the most recommended way to secure your seed phrase, as it adds an extra layer of protection even if your main seed phrase is compromised.
FAQ
Is it safe to make up my own seed phrase?
No. Relying on your own randomness or using memorable phrases makes them much easier to crack. You should let a cold storage wallet do it for you.
How do you generate a seed phrase with dice?
You can roll 100 six sided dice, write down the string of numbers, and run it through a SHA256 hash function. You then compute the checksum and append it to the hash to get your 264 bits.
What is the best physical storage for a seed phrase?
Users recommend metal plates over paper because they are fireproof, waterproof, and highly resistant to degradation. You should keep multiple metal plates in different physical locations.
Should I add a passphrase to my crypto wallet?
Yes. A passphrase acts as a 25th word to create a hidden wallet that requires both pieces to access the funds. Choose strong, random words for this and store it separately from your offline seed backup.
How does Shamir Secret Sharing work for crypto?
It is an advanced security method that splits your seed into multiple sets of words. A correctly set up system will give you three sets of 20 words that require two of the three to reconstruct the seed.
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