Added signature validation

src/main/scala/com/zambito/blockchain/Main.scala

@@ -1,9 +1,15 @@
 package com.zambito.blockchain
 
+import org.bouncycastle.jce.provider.BouncyCastleProvider
 import scala.xml.PrettyPrinter
+import java.security.Security
 
 
 object Main extends App {
+ Security.addProvider(new BouncyCastleProvider)
+
+ val bob = new Wallet
+ val alice = new Wallet
 
  lazy val blockchain: Blockchain =
  Block.mineBlock(Block("First block data", "0")) #::
@@ -22,9 +28,6 @@ object Main extends App {
  println("</blockchain>")
  }
 
-
- lazyBlockchainPrint(blockchain)
-
  def isChainValid: Blockchain => Boolean = {
  case fst +: snd +: tail
  if snd.hash == Block.calculateHash(snd) &&
@@ -39,5 +42,25 @@ object Main extends App {
  case _ => true
  }
 
+
+ println(s"Bob's private key: ${bob.privateKey}")
+ println(s"Bob's public key: ${bob.publicKey}")
+
+
+ val unsignedTransaction = Transaction(bob.publicKey, aklice.publicKey, 5, Seq[TransactionInput]())
+
+ val transaction = Transaction.signTransaction(
+ unsignedTransaction,
+ bob.privateKey
+ )
+
+
+ println(s"Valid signature on unsigned: ${unsignedTransaction.hasValidSignature}")
+ println(s"Valid signature: ${transaction.hasValidSignature}")
+ println(s"Transaction: $transaction")
+
+
+ lazyBlockchainPrint(blockchain)
+
  println(s"Is valid: ${isChainValid(blockchain)}")
 }

src/main/scala/com/zambito/blockchain/package.scala

@@ -1,10 +1,14 @@
 package com.zambito
 
+import java.security._
+import java.util.Base64
+
 package object blockchain {
- val DIFFICULTY = 5
+ val DIFFICULTY = 3
+
+ type Blockchain = Seq[Block]
 
  implicit class StringUtil(str: String) {
- import java.security.MessageDigest
 
  def encrypted(algorithm: String = "SHA-256"): String = {
  val digest = MessageDigest.getInstance(algorithm)
@@ -14,8 +18,31 @@ package object blockchain {
  .map(s => if(s.length == 1) s + "0" else s)
  .mkString
  }
+
+ def signData(privateKey: PrivateKey): Array[Byte] = {
+ val dsa = Signature.getInstance("ECDSA", "BC")
+ dsa.initSign(privateKey)
+ dsa.update(str.getBytes)
+ dsa.sign()
+ }
  }
 
- type Blockchain = Seq[Block]
+ implicit class KeyUtil(key: Key) {
+ def getStringFromKey: String =
+ Base64.getEncoder.encodeToString(key.getEncoded)
+ }
+
+ implicit class PublicKeyUtil(pk: PublicKey) {
+ def verifySig(data: String, signature: Array[Byte]): Boolean = {
+ try {
+ val ecdsaVerify = Signature.getInstance("ECDSA", "BC")
+ ecdsaVerify.initVerify(pk)
+ ecdsaVerify.update(data.getBytes)
+ ecdsaVerify.verify(signature)
+ } catch {
+ case _: Exception => false
+ }
+ }
+ }
 
 }