Generate public address using message and private from metamask

cripto.go

package cripto

import (
	"github.com/ethereum/go-ethereum/accounts"
	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/crypto"
)

// from: https://gist.github.com/dcb9/385631846097e1f59e3cba3b1d42f3ed#file-eth_sign_verify-go
func VerifySig(from, sigHex string, msg []byte) bool {
	sig := hexutil.MustDecode(sigHex)

	msg = accounts.TextHash(msg)
	if sig[crypto.RecoveryIDOffset] == 27 || sig[crypto.RecoveryIDOffset] == 28 {
		sig[crypto.RecoveryIDOffset] -= 27 // Transform yellow paper V from 27/28 to 0/1
	}

	recovered, err := crypto.SigToPub(msg, sig)
	if err != nil {
		return false
	}

	recoveredAddr := crypto.PubkeyToAddress(*recovered)

	return from == recoveredAddr.Hex()
}

// if return is "" something went wrong
func GeneratePublicAddress(message string, signature string) string {
	sig := hexutil.MustDecode(signature)

	msg := accounts.TextHash([]byte(message))
	if sig[crypto.RecoveryIDOffset] == 27 || sig[crypto.RecoveryIDOffset] == 28 {
		sig[crypto.RecoveryIDOffset] -= 27 // Transform yellow paper V from 27/28 to 0/1
	}

	recovered, err := crypto.SigToPub(msg, sig)
	if err != nil {
		return ""
	}

	recoveredAddr := crypto.PubkeyToAddress(*recovered)

	return recoveredAddr.Hex()
}