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I guess very few of my readers haven’t heard about BitCoin or Ethereum. Just when BitCoin started, one of my acquaintances wanted me to buy into it. I am a sceptic—always been, will probably always be—it’s hard-printed into my DNA. Before I go too far off-topic, let me stop here. I may not be completely into BitCoin and all the other cryptocurrencies (or digital currencies, or virtual currencies) such as Ethereum, Dogecoin, BlackCoin, Nxt, LiteCoin, PeerCoin, and Dash, but I do love the technology behind it: the BlockChain.
What Is the BlockChain?
A blockchain is a continuously growing ledger of facts, replicated across a peer-to-peer network. Facts can range from monetary transactions to content signatures. A blockchain is a distributed and a decentralized digital ledger that can be used to record transactions across numerous computers. This means that the record cannot be retroactively altered without the alteration of all subsequent blocks and the collusion of the network.
Each block in the BlockChain contains a hash pointer as a link or reference to a previous block, transaction data, and a timestamp. Blockchains are resistant to modification of the data. A Blockchain serves as an open and distributed ledger that can record transactions between different two parties a verifiable and permanent way.
A Blockchain database consists of two kinds of records: blocks and transactions. Blocks hold batches of valid transactions that are hashed and encoded into a hash tree (a hash tree is a tree in which every leaf node is labeled with a data block, and every non-leaf node is labeled with the cryptographic hash of the labels of its child nodes). Each block includes the hash of the previous block in the Blockchain, linking the two.
Cryptocurrencies
A cryptocurrency is a digital medium of exchange that makes use of cryptography to secure transactions and to control creation of additional units of the currency. Miners help maintain the integrity, safety, and balance Cryptocurrency ledgers, by using their computers to help validate and timestamp transactions. Some of the most popular Cryptocurrencies are the following:
- BitCoin
- Ethereum
- Dogecoin
- BlackCoin
- Nxt
- LiteCoin
- PeerCoin
BitCoin
BitCoin is the first decentralized digital currency. BitCoin is peer-to-peer, and transactions take place between users directly. These transactions are verified by network nodes and then recorded in a public-distributed ledger called a blockchain.
Ethereum
Ethereum is an open-source, blockchain-based distributed computing platform using smart contract scripting. Ethereum provides a decentralized Turing-complete virtual machine which can execute scripts using an international network of public nodes.
Dogecoin
Despite being introduced as a “joke currency” in 2013, Dogecoin quickly developed its own online community and reached a capitalization of $60 million in January 2014. In June 2017, it had a capitalization of $340 million.
BlackCoin
BlackCoin is also a peer-to-peer cryptocurrency. BlackCoin is open source and uses a proof-of-stake system. BlackCoin secures its network through a process called minting.
Nxt
Nxt is an open source cryptocurrency network. Nxt also uses a proof-of-stake system to reach consensus for transactions. Thus, it creates a static money supply and, unlike BitCoin, no mining is necessary.
LiteCoin
Litecoin has a lot of technical improvements over BitCoin, such as the adoption of the Lightning Network. Lightning Network uses an off-chain protocol and it features a P2P system for making micropayments of digital currencies such as BitCoin and LiteCoin through a scale-free network of bidirectional payment channels, without having to delegate custody of funds or trust to third parties.
PeerCoin
Peercoin is a peer-to-peer cryptocurrency utilizing both proof-of-stake and proof-of-work systems.
Creating a BlockChain in VB.NET
Be warned. This is not for the faint-hearted! Start Visual Studio and create a Visual Basic Class Library project. This project is loosely based on the Ethereum platform.
Add a class to your project and name it Node (or something similar). Add the following code to it:
Public Class Node Private btValue As Byte() Private btKey As Byte() End Class
You might say that that this isn’t difficult; well, I didn’t want to scare you away with the very first code segment! Add the following class to encode Bytes to Hexadecimal and vice versa:
Imports System.IO
Public NotInheritable Class CompactEncoder
Private Shared Delimiter As Byte = 16
Public Shared Function CompactEncode(btHex As Byte()) As Byte()
Dim btTerminate As Byte = 0
If btHex(btHex.Length - 1) = Delimiter Then
btTerminate = 1
btHex = Encoder.RemoveLastBytes(btHex, 1)
End If
Dim intOddLength As Integer = btHex.Length Mod 2
Dim intFlag As Integer = 2 * btTerminate + intOddLength
If intOddLength <> 0 Then
Dim btFlags As Byte() = New Byte() {CByte(intFlag)}
btHex = Encoder.JoinByteArrays(btFlags, btHex)
Else
Dim btFlags As Byte() = New Byte() {CByte(intFlag), 0}
btHex = Encoder.JoinByteArrays(btFlags, btHex)
End If
Dim msBuffer As New MemoryStream()
For i As Integer = 0 To btHex.Length - 1 Step 2
msBuffer.WriteByte(CByte(16 * btHex(i) + btHex(i + 1)))
Next
Return msBuffer.ToArray()
End Function
Public Shared Function CompactDecode(btString As Byte()) _
As Byte()
Dim btRes As Byte() = CompactHexDecode(btString)
btRes = Encoder.RemoveLastBytes(btRes, 1)
If btRes(0) >= 2 Then
btRes = Encoder.AppendByteToArray(btRes, Delimiter)
End If
If btRes(0) Mod 2 = 1 Then
btRes = Encoder.RemoveFirstBytes(btRes, 1)
Else
btRes = Encoder.RemoveFirstBytes(btRes, 2)
End If
Return btRes
End Function
Public Shared Function CompactHexDecode(btEncodedHexadecimal _
As Byte()) As Byte()
Dim chrCharacters As Char() = New Char() {"0"c, "1"c, "2"c, _
"3"c, "4"c, "5"c, "6"c, "7"c, "8"c, "9"c, "a"c, "b"c, _
"c"c, "d"c, "e"c, "f"c}
Dim btHex As Byte() = New Byte(-1) {}
For Each btNumber As Byte In btEncodedHexadecimal
Dim hexValue As String = btNumber.ConvertToHex()
Dim chrHexValue As Char() = hexValue.ToCharArray()
btHex = Encoder.AppendByteToArray(btHex, _
CByte(Array.IndexOf(chrCharacters, chrHexValue(0))))
btHex = Encoder.AppendByteToArray(btHex, _
CByte(Array.IndexOf(chrCharacters, chrHexValue(1))))
Next
btHex = Encoder.AppendByteToArray(btHex, Delimiter)
Return btHex
End Function
End Class
Add the following extension module to be able to convert Bytes into Hexadecimal:
Imports System.Text
Public Module Converter
Public Function ConvertByteArrayToUInt64(btInput As Byte()) _
As UInt64
If btInput.Length < 8 Then
Dim tempArray As Byte() = New Byte(7) {}
Array.Copy(btInput, 0, tempArray, (tempArray.Length - _
btInput.Length), btInput.Length)
Array.Reverse(tempArray)
Return BitConverter.ToUInt64(tempArray, 0)
End If
Return BitConverter.ToUInt64(btInput, 0)
End Function
Private ReadOnly HexStringTable As String() = New String() _
{"00", "01", "02", "03", "04", "05", "06", "07", "08", _
"09", "0a", "0b", "0c", "0d", "0e", "0f", "10", "11", "12", _
"13", "14", "15", "16", "17", "18", "19", "1a", "1b", "1c", _
"1d", "1e", "1f", "20", "21", "22", "23", "24", "25", "26", _
"27", "28", "29", "2a", "2b", "2c", "2d", "2e", "2f", "30", _
"31", "32", "33", "34", "35", "36", "37", "38", "39", "3a", _
"3b", "3c", "3d", "3e", "3f", "40", "41", "42", "43", "44", _
"45", "46", "47", "48", "49", "4a", "4b", "4c", "4d", "4e", _
"4f", "50", "51", "52", "53", "54", "55", "56", "57", "58", _
"59", "5a", "5b", "5c", "5d", "5e", "5f", "60", "61", "62", _
"63", "64", "65", "66", "67", "68", "69", "6a", "6b", "6c", _
"6d", "6e", "6f", "70", "71", "72", "73", "74", "75", "76", _
"77", "78", "79", "7a", "7b", "7c", "7d", "7e", "7f", "80", _
"81", "82", "83", "84", "85", "86", "87", "88", "89", "8a", _
"8b", "8c", "8d", "8e", "8f", "90", "91", "92", "93", "94", _
"95", "96", "97", "98", "99", "9a", "9b", "9c", "9d", "9e", _
"9f", "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", _
"a9", "aa", "ab", "ac", "ad", "ae", "af", "b0", "b1", "b2", _
"b3", "b4", "b5", "b6", "b7", "b8", "b9", "ba", "bb", "bc", _
"bd", "be", "bf", "c0", "c1", "c2", "c3", "c4", "c5", "c6", _
"c7", "c8", "c9", "ca", "cb", "cc", "cd", "ce", "cf", "d0", _
"d1", "d2", "d3", "d4", "d5", "d6", "d7", "d8", "d9", "da", _
"db", "dc", "dd", "de", "df", "e0", "e1", "e2", "e3", "e4", _
"e5", "e6", "e7", "e8", "e9", "ea", "be", "ec", "ed", "ee", _
"ef", "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", "f8", _
"f9", "fa", "fb", "fc", "fd", "fe", "ff"}
<System.Runtime.CompilerServices.Extension>
Public Function ConvertToHex(btVal As Byte()) As String
Dim sbString As New StringBuilder()
If btVal IsNot Nothing Then
For Each b As Byte In btVal
sbString.Append(HexStringTable(b))
Next
End If
Return sbString.ToString()
End Function
End Module
Add the following code to encode and decode objects received from Byte Arrays, which will be converted to hex later:
Public Class Decode
Private uPos As UInt64
Private oDecoded As [Object]
Public Sub New(Pos As UInt64, Decoded As [Object])
Me.uPos = Pos
Me.oDecoded = Decoded
End Sub
Public Function GetPos() As UInt64
Return uPos
End Function
Public Function GetDecoded() As [Object]
Return oDecoded
End Function
End Class
Imports System.Text
Public NotInheritable Class Encoder
Public Shared Function ToHex(oInput As [Object]) As Byte()
Dim uInput As UInt64
Dim blnNumber As Boolean = _
UInt64.TryParse(oInput.ToString(), uInput)
If blnNumber Then
Return If((uInput = 0), New Byte(-1) {}, _
ConvertUInt64ToByteArray(uInput))
ElseIf TypeOf oInput() Is String Then
Dim strInput As String = DirectCast(oInput(), String)
Return Encoding.ASCII.GetBytes(strInput.ToCharArray())
End If
End Function
Public Shared Function ConvertUInt64ToByteArray(uInput _
As UInt64) As Byte()
Dim btBytes As Byte() = BitConverter.GetBytes(uInput)
Array.Reverse(btBytes)
Dim i = 0
While btBytes(i) = 0
i += 1
End While
Dim btResult As Byte() = New Byte(btBytes.Length - i - 1) {}
Array.Copy(btBytes, i, btResult, 0, btBytes.Length - i)
Return btResult
End Function
Public Shared Function JoinByteArrays(btInputA As Byte(), _
btInputB As Byte()) As Byte()
Dim btResult As Byte() = New Byte(btInputA.Length + _
(btInputB.Length - 1)) {}
Array.Copy(btInputA, 0, btResult, 0, btInputA.Length)
Array.Copy(btInputB, 0, btResult, btInputA.Length, _
btInputB.Length)
Return btResult
End Function
Public Shared Function AppendByteToArray(btInputArr As Byte(), _
btInput As Byte) As Byte()
Dim btResult As Byte() = New Byte(btInputArr.Length) {}
Array.Copy(btInputArr, 0, btResult, 0, btInputArr.Length)
btResult(btResult.Length - 1) = btInput
Return btResult
End Function
Public Shared Function RemoveLastBytes(btInput As Byte(), _
intAmount As Integer) As Byte()
Dim btResult As Byte() = New Byte(btInput.Length - _
intAmount - 1) {}
Array.Copy(btInput, 0, btResult, 0, btInput.Length - _
intAmount)
Return btResult
End Function
Public Shared Function RemoveFirstBytes(btInput As Byte(), _
intAmount As Integer) As Byte()
Dim btResult As Byte() = New Byte(btInput.Length - _
intAmount - 1) {}
Array.Copy(btInput, intAmount, btResult, 0, _
btInput.Length - intAmount)
Return btResult
End Function
End Class
This is by no means all, but I have decided to stop here. Reason being: There soon will be a Part 2, where I will explain how to put the preceding classes to proper use inside a test project and add some more features.
The previous code deals with the whole logic of the blockchain, but we still need to be able to mine properly—which will come a bit later, so please be on the lookout!
Solidity
Solidity is a contract-oriented, high-level language designed to target the Ethereum Virtual Machine. You can use and program Solidity Blockchain apps straight from Visual Studio Code.
Download the extension here.
It is quite easy to set up and get started. So, if you do not want to wait for Part 2 of this series, you are welcome to follow the steps properly outlined here to get started.
Source code is available on GitHub.
Conclusion
This project is by no means 100% done, but it should give you the proper foundation to start your own blockchains. This was not as easy and quick as I thought that it would be.
