mnemonicToSeed
Converts a mnemonic phrase to a seed using PBKDF2-HMAC-SHA512.
This follows BIP-39 specification:
2048 iterations of PBKDF2
HMAC-SHA512
Optional passphrase (default: "")
Return
64-byte seed derived from mnemonic
Parameters
mnemonic
The BIP-39 mnemonic phrase
passphrase
Optional passphrase for additional security (default: empty)
Throws
if mnemonic is invalid