get Nostr nsec from BIP-0039 Mnemonic

bip39tonip19.go

package main

import (
	"fmt"
	"github.com/nbd-wtf/go-nostr"
	"github.com/nbd-wtf/go-nostr/nip19"
	"github.com/tyler-smith/go-bip32"
	"github.com/tyler-smith/go-bip39"
)

func main() {
	//entropy, _ := bip39.NewEntropy(256)
	entropy, _ := bip39.EntropyFromMnemonic("decide intact title offer slab wife swear family tumble initial sheriff dance canoe siren chicken wait eyebrow flee slide day slide boy patch average")
	mnemonic, _ := bip39.NewMnemonic(entropy)
	fmt.Println("Mnemonic: ", mnemonic)

	secret := "" // or "Secret Passphrase"
	seed := bip39.NewSeed(mnemonic, secret)
	masterKey, _ := bip32.NewMasterKey(seed)
	masterKey, _ = masterKey.NewChildKey(0)

	s, _ := masterKey.Serialize()
	raw := s[46:78]
	hexstr := ""
	for _, v := range raw {
		hexstr += fmt.Sprintf("%02x", v)
	}
	pk, _ := nostr.GetPublicKey(hexstr)
	nsec, _ := nip19.EncodePrivateKey(hexstr)
	npub, _ := nip19.EncodePublicKey(pk)
	fmt.Println(nsec)
	fmt.Println(npub)
}