Basic Bitcoin tx verifier

p2pk_p2pkh_signature_compare.go

package main

import (
	"encoding/hex"
	"fmt"

	"github.com/btcsuite/btcd/btcec/v2"
	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
	"github.com/btcsuite/btcd/chaincfg/chainhash"
)

func main() {
	// working p2pk signature
	// pubKeyHex := "0411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3"
	// messageHex := "0100000001c997a5e56e104102fa209c6a852dd90660a20b2d9c352423edce25857fcd37040000000043410411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3acffffffff0200ca9a3b00000000434104ae1a62fe09c5f51b13905f07f06b99a2f7159b2225f374cd378d71302fa28414e7aab37397f554a7df5f142c21c1b7303b8a0626f1baded5c72a704f7e6cd84cac00286bee0000000043410411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3ac0000000001000000"
	// signatureHex := "304402204e45e16932b8af514961a1d3a1a25fdf3f4f7732e9d624c6c61548ab5fb8cd410220181522ec8eca07de4860a4acdd12909d831cc56cbbac4622082221a8768d1d0901"

	// not working p2pk signature
	pubKeyHex := "04889fcdfd7c5430d13f1eb5f508e2e87f38d2406fad8425a824e032ccb371ef62465331e1a6334d7c3770a2ad2a958e740130343399d01dbd87426db850f9faf9"
	messageHex := "01000000020dd7891efbf67da47c651531db8aab3144ed7a524e4ae1e30b773525e27ddd7b00000000434104889fcdfd7c5430d13f1eb5f508e2e87f38d2406fad8425a824e032ccb371ef62465331e1a6334d7c3770a2ad2a958e740130343399d01dbd87426db850f9faf9acffffffff16851666962e37a75a246101f2e340c628b1db3c045d4d3cfb2d1c0f58f97c6f0000000000ffffffff02c0c62d00000000001976a91417194e1bd175fb5b1b2a1f9d221f6f5c29e1928388ac00c817a8040000001976a91465bda9b05f7e9a8f96a7f4ba0996a877708ef90888ac0000000001000000"
	signatureHex := "304502206f6a68710a51f77e5a1fa4d1037a23a76723724a51fd54710949e0189ee02dfa022100dad3454ade12fe84f3818e14c41ec2e02bbb154dd3136a094cdf86f67ebbe0b601"

	// Decode the public key
	pubKeyBytes, err := hex.DecodeString(pubKeyHex)
	if err != nil {
		fmt.Println("Error decoding public key:", err)
		return
	}
	pubKey, err := btcec.ParsePubKey(pubKeyBytes)
	if err != nil {
		fmt.Println("Error parsing public key:", err)
		return
	}

	// Decode the message (transaction hash)
	messageBytes, err := hex.DecodeString(messageHex)
	if err != nil {
		fmt.Println("Error decoding message:", err)
		return
	}
	messageHash := chainhash.DoubleHashB(messageBytes)

	// Decode the signature
	signatureBytes, err := hex.DecodeString(signatureHex)
	if err != nil {
		fmt.Println("Error decoding signature:", err)
		return
	}
	signature, err := ecdsa.ParseDERSignature(signatureBytes)
	if err != nil {
		fmt.Println("Error parsing signature:", err)
		return
	}
	fmt.Println("Message Hash:", hex.EncodeToString(messageHash))

	// Verify the signature
	valid := signature.Verify(messageHash, pubKey)

	if valid {
		fmt.Println("Signature is valid!")
	} else {
		fmt.Println("Signature is invalid!")
	}
}