Advanced info
Entropy
Entropy values should not include the BIP39 checksum. This is automatically added by the tool.
Entropy values must be sourced from a
strong source of randomness.
This means flipping a fair coin, rolling a fair dice, noise measurements etc.
Do NOT use phrases from books, lyrics from songs, your birthday or street address,
keyboard mashing, or anything you think is random, because chances are overwhelming it isn't
random enough for the needs of this tool.
Do not store entropy.
Storing entropy (such as keeping a deck of cards in a specific shuffled order) is unreliable compared to storing a mnemonic.
Instead of storing entropy, store the mnemonic generated from the entropy.
Steganography may be beneficial when storing the mnemonic.
The random mnemonic generator on this page uses a
cryptographically secure random number generator.
The built in random generator can generally be trusted more than your own intuition about randomness.
If cryptographic randomness isn't available in your browser, this page will show a warning and the generate button will not work.
In that case you might choose to use your own source of entropy.
You are not a good source of entropy.
Card entropy has been implemented assuming cards are replaced, not drawn one after another.
A full deck with replacement generates 232 bits of entropy (21 words). A full deck without replacement generates 225 bits of entropy (21 words).
PBKDF2
What is PBKDF2 (Password Based Key Derivation Function 2) ?
Please refer to this wikipedia article for more detail.
Mail about PBKDF2 security here.
Wallet software that implement BIP39 only use 2048 iterations as a norm. Increasing this parameter will increase security against brute force attack, but you will need to store this new parameter. However, as long as you back up your BIP39 seed there will not be risk to lost your fund. To access them with custom PBKDF2 iterations, use this file (or other) to compute your targeted BIP39 seed.
Using less than 2048 PBKDF2 iterations is insecure without strong optional BIP39 Passphrase.