add tome TODOs & hash functions

src/main/scala/com/github/fluency03/blockchain/Serde.scala

@@ -0,0 +1,26 @@
+package com.github.fluency03.blockchain
+
+import java.io.{ByteArrayInputStream, ByteArrayOutputStream, ObjectInputStream, ObjectOutputStream}
+
+/**
+ * Ser(ialization) and De(serialization)
+ */
+object Serde {
+
+  def serialize[T](value: T): Bytes = {
+    val stream: ByteArrayOutputStream = new ByteArrayOutputStream()
+    val oos = new ObjectOutputStream(stream)
+    oos.writeObject(value)
+    oos.close()
+    stream.close()
+    stream.toByteArray
+  }
+
+  def deserialize[T](bytes: Array[Byte]): T = {
+    val ois = new ObjectInputStream(new ByteArrayInputStream(bytes))
+    val value = ois.readObject
+    ois.close()
+    value.asInstanceOf[T]
+  }
+
+}

src/main/scala/com/github/fluency03/blockchain/core/Block.scala

@@ -92,6 +92,7 @@ object Block {
     0, ZERO64, "Welcome to Blockchain in Scala!", genesisTimestamp, difficulty,
     Seq(createCoinbaseTx(0, genesisMiner, genesisTimestamp)))
 
+  // TODO (Chang): implement parallel version
   def mineNextBlock(
       nextIndex: Int,
       prevHash: String,

src/main/scala/com/github/fluency03/blockchain/core/Merkle.scala

@@ -5,9 +5,14 @@ import com.github.fluency03.blockchain.crypto.SHA256
 
 import scala.annotation.tailrec
 
+// TODO (Chang): implement a full nodes merkle tree
+
+
 object Merkle {
   def computeRoot(trans: Seq[Transaction]): String = computeRootOfHashes(trans.map(_.id))
 
+  // TODO (Chang): double SHA256 hash instead of single.
+  // TODO (Chang): hash and concatenate hash string or hash bytes?
   @tailrec
   def computeRootOfHashes(hashes: Seq[String]): String = hashes.length match {
     case 0 => ZERO64
@@ -16,4 +21,16 @@ object Merkle {
     case _ => computeRootOfHashes(hashes.grouped(2).map { a => SHA256.hashAll(a(0), a(1)) } .toList)
   }
 
+  @tailrec
+  def hashViaMerklePath(init: String, path: Seq[String], index: Int): String =
+    if (path.isEmpty) init
+    else {
+      val newHash = if (index % 2 == 0) SHA256.hashAll(init, path.head) else SHA256.hashAll(path.head, init)
+      hashViaMerklePath(newHash, path.tail, index/2)
+    }
+
+  def simplifiedPaymentVerification(init: String, root: String, path: Seq[String], index: Int): Boolean =
+    hashViaMerklePath(init, path, index) == root
+
+
 }

src/main/scala/com/github/fluency03/blockchain/core/Transaction.scala

@@ -12,6 +12,7 @@ import org.json4s.{Extraction, JValue}
 import scala.collection.mutable
 
 case class Outpoint(id: String, index: Int)
+// TODO (Chang): add public key into TxIn
 case class TxIn(previousOut: Outpoint, signature: String)
 case class TxOut(address: String, amount: Long)
 

src/main/scala/com/github/fluency03/blockchain/crypto/RIPEMD160.scala

@@ -17,9 +17,8 @@ object RIPEMD160 {
     out
   }
 
-  def doubleHash(bytes: Bytes): String = hash(SHA256.hashToDigest(bytes))
-
-  def doubleHashToDigest(bytes: Bytes): Bytes = hashToDigest(SHA256.hashToDigest(bytes))
+  def hash160(bytes: Bytes): String = hash(SHA256.hashToDigest(bytes))
 
+  def hash160ToDigest(bytes: Bytes): Bytes = hashToDigest(SHA256.hashToDigest(bytes))
 
 }

src/main/scala/com/github/fluency03/blockchain/crypto/SHA256.scala

@@ -28,5 +28,8 @@ object SHA256 {
    */
   def hashAll(strings: String*): String = hash(strings mkString "")
 
+  def hash256(bytes: Bytes): String = hash(hashToDigest(bytes))
+
+  def hash256ToDigest(bytes: Bytes): Bytes = hashToDigest(hashToDigest(bytes))
 
 }

src/main/scala/com/github/fluency03/blockchain/crypto/Secp256k1.scala

@@ -90,6 +90,9 @@ object Secp256k1 {
   def publicKeyToAddress(publicKey: PublicKey, networkBytes: String = "00"): String =
     Base58.checkEncode(networkBytes.hex2Bytes ++ publicKeyToBytes(publicKey).toHash160Digest)
 
+  def hash160ToAddress(hash160: String, networkBytes: String = "00"): String =
+    Base58.checkEncode(networkBytes.hex2Bytes ++ hash160.hex2Bytes)
+
   def addressToHash160(address: String, networkBytes: String = "00"): (String, String) = {
     val decoded: Bytes = Base58.decode(address)
     val (preBytes, fourBytes) = decoded.splitAt(decoded.length - 4)

src/main/scala/com/github/fluency03/blockchain/package.scala

@@ -4,7 +4,7 @@ import java.nio.charset.Charset
 import java.security.{PrivateKey, PublicKey}
 import java.time.Instant
 
-import com.github.fluency03.blockchain.crypto.Secp256k1.{privateKeyToHex, publicKeyToHex}
+import com.github.fluency03.blockchain.crypto.Secp256k1
 import com.github.fluency03.blockchain.core.{Peer, PeerSimple, TxIn, TxOut}
 import com.github.fluency03.blockchain.crypto.{RIPEMD160, SHA256, Secp256k1}
 import org.bouncycastle.util.encoders.{Base64, Hex}
@@ -59,17 +59,20 @@ package object blockchain {
     def toSha256Digest: Bytes = SHA256.hashToDigest(bytes)
     def toRipemd160: String = RIPEMD160.hash(bytes)
     def toRipemd160ODigest: Bytes = RIPEMD160.hashToDigest(bytes)
-    def toHash160: String = RIPEMD160.doubleHash(bytes)
-    def toHash160Digest: Bytes = RIPEMD160.doubleHashToDigest(bytes)
+    def toHash160: String = RIPEMD160.hash160(bytes)
+    def toHash160Digest: Bytes = RIPEMD160.hash160ToDigest(bytes)
   }
 
   implicit class PublicKeyImplicit(val publicKey: PublicKey) {
-    def toHex: String = publicKeyToHex(publicKey)
+    def toHex: String = Secp256k1.publicKeyToHex(publicKey)
+    def toBytes: Bytes = Secp256k1.publicKeyToBytes(publicKey)
+    def toHash160: String = Secp256k1.publicKeyToBytes(publicKey).toHash160
     def address: String = Secp256k1.publicKeyToAddress(publicKey)
   }
 
   implicit class PrivateKeyImplicit(val privateKey: PrivateKey) {
-    def toHex: String = privateKeyToHex(privateKey)
+    def toHex: String = Secp256k1.privateKeyToHex(privateKey)
+    def toBytes: Bytes = Secp256k1.privateKeyToBytes(privateKey)
   }
 
   implicit class PeerImplicit(val peer: Peer) {

src/test/scala/com/github/fluency03/blockchain/crypto/RIPEMD160Test.scala

@@ -10,11 +10,11 @@ class RIPEMD160Test extends FlatSpec with Matchers {
     RIPEMD160.hash("173BDED8F2A2069C193E63EA30DC8FD20E815EC3642B9C24AD7002C03D1BFB9B".hex2Bytes) shouldEqual
       "88C2D2FA846282C870A76CADECBE45C4ACD72BB6".toLowerCase
 
-    RIPEMD160.doubleHashToDigest(("04b4d653fcbb4b96000c99343f23b08a44fa306031e0587f9e657ab4a25411" +
+    RIPEMD160.hash160ToDigest(("04b4d653fcbb4b96000c99343f23b08a44fa306031e0587f9e657ab4a25411" +
       "29368d7d9bb05cd8afbdf7705a6540d98028236965553f91bf1c5b4f70073f55b55d").hex2Bytes) shouldEqual
       "88C2D2FA846282C870A76CADECBE45C4ACD72BB6".hex2Bytes
 
-    RIPEMD160.doubleHash(("04b4d653fcbb4b96000c99343f23b08a44fa306031e0587f9e657ab4a25411" +
+    RIPEMD160.hash160(("04b4d653fcbb4b96000c99343f23b08a44fa306031e0587f9e657ab4a25411" +
       "29368d7d9bb05cd8afbdf7705a6540d98028236965553f91bf1c5b4f70073f55b55d").hex2Bytes) shouldEqual
       "88C2D2FA846282C870A76CADECBE45C4ACD72BB6".toLowerCase