From 23ca111b95640b898b33d63b805b4994eb740101 Mon Sep 17 00:00:00 2001
From: AlinaOktyabrskaya <44409263+AlinaOktyabrskaya@users.noreply.github.com>
Date: Fri, 2 Nov 2018 23:47:55 +0300
Subject: [PATCH 1/2] Update Main.java

---
 src/blockchain/Main.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/blockchain/Main.java b/src/blockchain/Main.java
index adf1d02..127549e 100644
--- a/src/blockchain/Main.java
+++ b/src/blockchain/Main.java
@@ -2,6 +2,6 @@
 
 public class Main {
     public static void main(String[] args) {
-        System.out.print("Hello world!");
+          new Blockchain();
     }
-}
\ No newline at end of file
+}

From 8fac7564ffbf670d83f890212d6b272fa014a810 Mon Sep 17 00:00:00 2001
From: AlinaOktyabrskaya <44409263+AlinaOktyabrskaya@users.noreply.github.com>
Date: Fri, 2 Nov 2018 23:50:29 +0300
Subject: [PATCH 2/2] Create  Blockchain.java

---
 src/blockchain/Blockchain.java | 82 ++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 src/blockchain/Blockchain.java

diff --git a/src/blockchain/Blockchain.java b/src/blockchain/Blockchain.java
new file mode 100644
index 0000000..7a15583
--- /dev/null
+++ b/src/blockchain/Blockchain.java
@@ -0,0 +1,82 @@
+import java.security.MessageDigest;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+public class Blockchain {
+
+
+    Blockchain(){
+
+
+        int id = 1;
+        int starthash = 0;
+
+        int time = 3;
+        String previoushash = Integer.toString(starthash);
+        String currenthash = "";
+        Boolean sec;
+
+
+        for(int i = 0; i < time; i ++)
+        {
+            System.out.println("Block:");
+            System.out.println("id: " + id);
+
+            currenthash = GenerateBlock(previoushash);
+            String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime().hashCode());
+            System.out.println("Timestamp: " + timeStamp);
+            System.out.println("Hash of the previous block: " + previoushash);
+            System.out.println("Hash of the block: "+ currenthash);
+
+            sec = validate(previoushash, currenthash);
+
+            if (sec){
+                previoushash = currenthash;
+                id++;
+                System.out.println();
+            }else{
+                System.out.println("Hash dont valid!!!");
+
+                break;
+            }
+
+
+
+
+        }
+
+
+
+
+    }
+
+    private Boolean validate(String previousblock, String currentblock) {
+        String check = GenerateBlock(previousblock);
+        if(check.equals(currentblock)){
+            return true;
+        }else {
+            return false;
+        }
+
+    }
+
+    private String GenerateBlock(String currentid) {
+        try {
+            MessageDigest digest = MessageDigest.getInstance("SHA-256");
+            /* Applies sha256 to our input */
+            byte[] hash = digest.digest(currentid.getBytes("UTF-8"));
+            StringBuilder hexString = new StringBuilder();
+            for (byte elem: hash) {
+                String hex = Integer.toHexString(0xff & elem);
+                if(hex.length() == 1) hexString.append('0');
+                hexString.append(hex);
+            }
+            return hexString.toString();
+        }
+        catch(Exception e) {
+            throw new RuntimeException(e);
+        }
+
+    }
+
+
+}