Mnemonic Phrases and Personal Wallet Security (feat. The Odds of Getting Hacked)
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Today, most personal wallets such as MetaMask generate a master key from a mnemonic phrase (or seed phrase). But how secure is this method?
Could someone hack my wallet by trying seed phrases at random? What exactly are the odds that a hacker drains my wallet?
In this post, we'll look at how mnemonic phrases are generated and how secure they are, and then take a closer look at the security and safety of the personal wallets built on them.
What Is a Mnemonic Phrase?
A mnemonic phrase (Seed Phrase), or seed phrase, is a combination of words used in decentralized wallets to generate wallet addresses or recover access. It usually consists of 12, 18, or 24 words.
For example, wallet software like MetaMask follows the BIP39 standard and randomly picks a 12-word seed phrase from a list of 2048 words. This seed phrase is essential when you recover your wallet or set it up on a new device.
How Mnemonic Phrases Are Generated, and How Secure They Are
First, let's look at how wallet addresses are created from a mnemonic phrase. The wallet software randomly selects 12 of the 2048 words to form a seed phrase, and a master key (private key) is generated from that seed phrase. Multiple wallet addresses (public keys) are then derived from this master key.
Because this process is based on a high degree of randomness and complexity, it provides considerable security. And if the wallet also uses its own encryption algorithm, the randomness of the mnemonic phrase becomes even higher.
The Odds of a Mnemonic Phrase Being Guessed or Duplicated
The probability of the same mnemonic phrase being used twice is close to 0%. For a 12-word seed phrase, the number of possible combinations is 2048^12 = 2^132 = 5.4 * 10^39. That's a probability so small that even if every computer in the world generated billions of seed phrases every second, it would take billions of years for just a single match to occur.
For a 24-word seed phrase, there are 2048^24 = 2^256 = 1.5 * 10^79 possible combinations. That's far more than the number of atoms in the observable universe. In other words, the chance of a mnemonic phrase being duplicated is effectively 0%.
| Number of words | Possible combinations | Comparison |
|---|---|---|
| 12-word seed | 2048^12 (about 5.4 * 10^39) | Even if every computer in the world generated billions of seed phrases every second, it would take billions of years for a single match to occur |
| 24-word seed | 2048^24 (about 1.5 * 10^79) | More than the number of atoms in the observable universe |
How to Keep Your Mnemonic Phrase Safe
No matter how secure managing a wallet with a mnemonic phrase may be, if the seed phrase is leaked, you could lose every asset in your wallet. That's why it's so important to keep your mnemonic phrase safe.
The safest way to store it is offline. For example, write your mnemonic phrase on paper and keep it in a secure safe, or store it in a safe, physically separate location.
Also, you should never store your mnemonic phrase online or in digital form. There are frequent reports of people getting their wallets hacked after saving their phrase "just in case" in an email, or taking a screenshot and keeping it in their photo album or the cloud.
Wrapping Up
Creating and managing a wallet with a mnemonic phrase is currently considered a very secure method. The chance of the same 12-word mnemonic phrase being generated twice is extremely slim, effectively close to 0%. In conclusion, the system of creating and managing wallets with mnemonic keys can be considered very secure.
Of course, in theory the possibility of a phrase being duplicated or guessed isn't exactly zero, but the probability is so low that it can be safely ignored. So be sure to store your mnemonic phrase securely and protect your valuable assets.
