consolidate all repos to one for archive

semester_3/racunalniska_omrezja/naloga_5/5_Naloga/ConsoleTest.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <RootNamespace>_5_Naloga</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

semester_3/racunalniska_omrezja/naloga_5/5_Naloga/Program.cs

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+using System;
+using System.Collections.Generic;
+using System.Security.Cryptography;
+using System.Text;
+using System.Text.Json;
+
+namespace TestConsole
+{
+    class Block
+    {
+        public int Index { get; set; }
+        public string PreviousHash { get; set; }
+        public string Hash { get; set; }
+        public string Data { get; set; }
+        public long Timestamp { get; set; }
+        public int Nonce { get; set; }
+
+        public Block(int index, string previousHash, string data)
+        {
+            Index = index;
+            PreviousHash = previousHash;
+            Data = data;
+            Timestamp = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+            Nonce = 0;
+            Hash = CalculateHash();
+        }
+
+        public string CalculateHash()
+        {
+            using (SHA256 sha256 = SHA256.Create())
+            {
+                string hash = "";
+                byte[] inputBytes = Encoding.UTF8.GetBytes($"{Index}{PreviousHash}{Timestamp}{Data}{Nonce}");
+                byte[] outputBytes = sha256.ComputeHash(inputBytes);
+                hash = Convert.ToBase64String(outputBytes);
+
+                while (hash.Substring(0,3) != "000")
+                {
+                    Nonce++;
+                    inputBytes = Encoding.UTF8.GetBytes($"{Index}{PreviousHash}{Timestamp}{Data}{Nonce}");
+                    outputBytes = sha256.ComputeHash(inputBytes);
+                    hash = Convert.ToBase64String(outputBytes);
+                }
+                return hash;
+            }
+        }
+    }
+
+    class Blockchain
+    {
+        public List<Block> Chain { get; set; }
+
+        public Blockchain()
+        {
+            Chain = new List<Block>();
+            Chain.Add(new Block(0, "", ""));
+        }
+
+        public Block GetLatestBlock()
+        {
+            return Chain[Chain.Count - 1];
+        }
+
+        public void AddBlock(string data)
+        {
+            Block latestBlock = GetLatestBlock();
+            int index = latestBlock.Index + 1;
+            string previousHash = latestBlock.Hash;
+            Chain.Add(new Block(index, previousHash, data));
+        }
+
+        public bool IsValid()
+        {
+
+            for (int i = 1; i < Chain.Count; i++)
+            {
+                Block currentBlock = Chain[i];
+                Block previusBlock = Chain[i - 1];
+
+                if (currentBlock.PreviousHash != previusBlock.Hash) return false;
+                if (currentBlock.Hash != currentBlock.CalculateHash()) return false;
+                if (currentBlock.Index != previusBlock.Index + 1) return false;
+                return true;
+            }
+
+            return false;
+        }
+
+    }
+
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            Blockchain blockchain = new Blockchain();
+
+            blockchain.AddBlock("This is block 1");
+            blockchain.AddBlock("This is block 2");
+            blockchain.AddBlock("This is block 3");
+
+            var options = new JsonSerializerOptions { WriteIndented = true };
+            string blockString = JsonSerializer.Serialize(blockchain.Chain, options);
+
+            Console.WriteLine(blockString);
+            /*
+            foreach (Block block in blockchain.Chain)
+            {
+                Console.WriteLine($"Index: {block.Index}");
+                Console.WriteLine($"Previous Hash: {block.PreviousHash}");
+                Console.WriteLine($"Hash: {block.Hash}");
+                Console.WriteLine($"Data: {block.Data}");
+                Console.WriteLine($"Timestamp: {block.Timestamp}");
+                Console.WriteLine();
+            }
+
+            Console.WriteLine(blockchain.IsValid() ? "Block Chen is valid" : "BlockChain is invalid");
+            */
+        }
+    }
+}