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--- crypto_1 [2025/05/27 10:45] – frchris
+++ crypto_1 [2025/05/27 11:40] (current) – frchris
@@ Line 1: / Line 1: @@
-====== Crypto 1 (Vegnere) ======
+====== Crypto 1 (Vigenère) ======
 [[https://www.mathorama.com/gsp/Crypto%20WS.pdf|Worksheet]] With Riddles
+[[https://en.wikipedia.org/wiki/Vigenère_cipher|History of this Cipher Method]]
+<code java Crypto.java>
+import java.util.Scanner;
+/**
+ * Write a description of class Crypto here.
+ *
+ * @author Chris Thiel, OFMCap
+ * @version 23 May 2025
+ */
+public class Crypto
+{
+    private String key;
+    private final String  ALPHA="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    /**
+     * Constructor for objects of class Crypto
+     */
+    public Crypto()
+    {
+        key = "UNIKNOWN";
+    }
+    public void setKey(String key){
+        this.key = key.toUpperCase();
+    }
+    public Crypto(String key)
+    {
+        setKey ( key );
+    }
+    public String getKey(){
+        return key;
+    }
+    public String encode(String message)
+    {
+        String result ="";
+        for (int i = 0; i< message.length(); i++)
+        {
+            char k = key.charAt( i % key.length() );
+            char m = message.toUpperCase().charAt(i);
+            int kIndex = ALPHA.indexOf(k);
+            int mIndex = ALPHA.indexOf(m);
+            result += ALPHA.charAt( (kIndex + mIndex) % 26);
+        }
+        return result;
+    }
+    public String decode(String message)
+    {
+        String result ="";
+        for (int i = 0; i< message.length(); i++)
+        {
+            char k = key.charAt( i % key.length() );
+            char m = message.toUpperCase().charAt(i);
+            int kIndex = ALPHA.indexOf(k);
+            int mIndex = ALPHA.indexOf(m);
+            result += ALPHA.charAt( (26+mIndex-kIndex) % 26);
+        }
+        return result;
+    }
+    public static void main(String[] args)
+    {
+        System.out.println("Vigenere Cyptography ver 1.0 ");
+        Scanner kb = new Scanner(System.in);
+        System.out.print("What is the key? ");
+        String line = kb.nextLine();
+        Crypto code = new Crypto(line);
+        while (! line.equals("Q") ){
+            System.out.print("Key is "+ code.key +" E)ncode, D)ecode, C)hange Key, Q)uit  Commend: ");
+            line = kb.nextLine().toUpperCase();
+            char cmd = line.charAt(0);
+            switch ( cmd ) {
+                case 'C' :
+                    System.out.print("What is the key? ");
+                    String newKey = kb.nextLine();
+                    code.setKey(newKey);
+                    break;
+                case 'E' :
+                    System.out.print("Encode what message?");
+                    String message = kb.nextLine();
+                    System.out.println(code.encode(message));
+                    break;
+                case 'D' :
+                    System.out.print("Decode what message?");
+                    message = kb.nextLine();
+                    System.out.println(code.decode(message));
+                    break;
+            }
+        }
+        System.out.println("Bye!");
+    }
+}
+</code>
+[[https://www.mathorama.com/ti/CRYPTO.png|My TI-84 Basic Listing]]
+[[https://www.mathorama.com/ti/CRYPTO.8xp|CRYPTO.8xp]] (to send to your TI-84)
 Back to [[New Labs]]