Error : only uncompressed keys are accepted post-segwit

[koderholic]

`
func SignTransaction(redeemTx *wire.MsgTx, secret string, destination string, amount float64, utxos []dto.Utxo) error {

privByte, _ := hex.DecodeString(privKey)
privateKey, pubKey := btcec.PrivKeyFromBytes( btcec.S256(), privByte)
fromAddress, _ := btcutil.NewAddressWitnessPubKeyHash(btcutil.Hash160(pubKey.SerializeUncompressed()), &chaincfg.MainNetParams)

sourceAddress, err := btcutil.DecodeAddress(fromAddress, &chaincfg.MainNetParams)
destinationAddress, err := btcutil.DecodeAddress(destination, &chaincfg.MainNetParams)
if err != nil {
	return err
}

// TODO : Calculate fee estimation
estimatedFee, err := btcutil.NewAmount(0.0001) 
if err != nil {
	return err
}
satoshiAmount, err := btcutil.NewAmount(amount) 
if err != nil {
	return err
}
totalSatoshiAmount := satoshiAmount + estimatedFee 

// TODO : optimize for selecting which UTXO to be used
totalSum := int64(0)
for i := 0; i < len(utxos); i++ {
	txValue, err := strconv.Atoi(utxos[i].Value)
	if err != nil {
		return err
	}
	totalSum += int64(txValue)

	sourceUtxoHash, _ := chainhash.NewHashFromStr(utxos[i].Txid)
	prevOut := wire.NewOutPoint(sourceUtxoHash, uint32(i))
	redeemTxIn := wire.NewTxIn(prevOut, nil, nil)
	redeemTx.AddTxIn(redeemTxIn)
	if totalSum > int64(totalSatoshiAmount) {
		break
	}
}

// Prepare pay to witness public script and add transaction outputs 
sourcePkScriptForOutput, _ := txscript.PayToAddrScript(sourceAddress)
destinationPkScriptForOutput, _ := txscript.PayToAddrScript(destinationAddress)
change := totalSum - int64(totalSatoshiAmount)
changeTxOut := wire.NewTxOut(int64(change), sourcePkScriptForOutput)
redeemTx.AddTxOut(changeTxOut)
redeemTxOut := wire.NewTxOut(int64(satoshiAmount), destinationPkScriptForOutput)
redeemTx.AddTxOut(redeemTxOut)

// Signing transaction
sigHash := txscript.NewTxSigHashes(redeemTx)
witnessSig, err := txscript.WitnessSignature(redeemTx, sigHash, 0, int64(satoshiAmount), sourcePkScriptForOutput, txscript.SigHashAll, privateKey, false)
if err != nil {
	return err
}

redeemTx.TxIn[0].Witness = witnessSig
flags := txscript.StandardVerifyFlags
vm, err := txscript.NewEngine(sourcePkScriptForOutput, redeemTx, 0, flags, nil, sigHash, int64(satoshiAmount))
if err != nil {
	fmt.Println("flag transactionerr > ", err)
	return err
}
if err := vm.Execute(); err != nil {
	fmt.Println("vm transactionerr > ", err)
	return err
}

return nil

}`

The above is to spend UTXO from a segwit address to a receiving segwit address, I am not sure if the issue I am having is with the implement, but I keep getting : Only uncompressed keys are accepted post-segwit when the code execution gets to vm.Execute() failing to validate the signature.

[JeremyRubin]

It looks like the error message you're getting is inaccurate. According to https://github.com/btcsuite/btcd/blob/master/txscript/engine.go#L587 and the segwit spec, keys must be compressed inside segwit.

Make sure your pubkey is compressed!

[koderholic]

@JeremyRubin Thank you for the response, I have tried making it compressed, but couldn't get it to work still. Had to move to implement it in Java.

[JeremyRubin]

I don't know anything about how competent the Java Bitcoin libraries are these days so it might make sense to wait until a maintainer/contributor of btcd can chime in on this issue; I believe btcd enjoys much more ecosystem support than java implementations I'm aware of.

[koderholic]

Yeah! But the Java implementation seems a bit straightforward. I think to continue with it, pending when a maintainer/contributor can help out with this issue.

[jakesylvestre]

keys must be compressed - can you link to the implementation you're referencing? Is this Bitcoinj?