seed property
BIP39: To create a binary seed from the mnemonic, we use the PBKDF2 function with a mnemonic sentence (in UTF-8 NFKD) used as the password and the string "mnemonic" + passphrase (again in UTF-8 NFKD) used as the salt. The iteration count is set to 2048 and HMAC-SHA512 is used as the pseudo-random function. The length of the derived key is 512 bits (= 64 bytes). This seed can be later used to generate deterministic wallets using BIP-0032 or similar methods.
Implementation
List<int> get seed {
var normalize = sentence.replaceAll(language.separator, '\u{0020}');
return pbkdf2(normalize, passphrase: passphrase);
}