CaesarCipher by Coursera

Author: muskan258

java/CaesarCipher/CaesarCipher.ctxt

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+#BlueJ class context
+comment0.target=CaesarCipher
+comment1.params=input\ key
+comment1.target=java.lang.String\ encrypt(java.lang.String,\ int)
+comment2.params=
+comment2.target=void\ testCaesar()
+numComments=3

java/CaesarCipher/CaesarCipher.java

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+import edu.duke.*;
+
+public class CaesarCipher {
+    public String encrypt(String input, int key) {
+        //Make a StringBuilder with message (encrypted)
+        StringBuilder encrypted = new StringBuilder(input);
+        //Write down the alphabet
+        String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+        //Compute the shifted alphabet
+        String shiftedAlphabet = alphabet.substring(key)+
+        alphabet.substring(0,key);
+        //Count from 0 to < length of encrypted, (call it i)
+        for(int i = 0; i < encrypted.length(); i++) {
+            //Look at the ith character of encrypted (call it currChar)
+            char currChar = encrypted.charAt(i);
+            //Find the index of currChar in the alphabet (call it idx)
+            int idx = alphabet.indexOf(currChar);
+            //If currChar is in the alphabet
+            if(idx != -1){
+                //Get the idxth character of shiftedAlphabet (newChar)
+                char newChar = shiftedAlphabet.charAt(idx);
+                //Replace the ith character of encrypted with newChar
+                encrypted.setCharAt(i, newChar);
+            }
+            //Otherwise: do nothing
+        }
+        //Your answer is the String inside of encrypted
+        return encrypted.toString();
+    }
+    public void testCaesar() {
+        int key = 17;
+        FileResource fr = new FileResource();
+        String message = fr.asString();
+        String encrypted = encrypt(message, key);
+        System.out.println(encrypted);  
+        String decrypted = encrypt(encrypted, 26-key);
+        System.out.println(decrypted);
+    }
+}
+

java/CaesarCipher/message1.txt

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+FREE CAKE IN THE CONFERENCE ROOM!
+

java/CaesarCipher/message2.txt

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+Dear Owen,
+  No matter what you may have heard, there is no cake
+in the conference room.  The cake is a lie.  Please keep
+working on Coursera videos.
+   
+Thanks,
+Drew

java/CaesarCipher/package.bluej

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+#BlueJ package file
+editor.fx.0.height=34
+editor.fx.0.width=199
+editor.fx.0.x=-32000
+editor.fx.0.y=-32000
+objectbench.height=90
+objectbench.width=758
+package.divider.horizontal=0.6
+package.divider.vertical=0.7983367983367984
+package.editor.height=377
+package.editor.width=652
+package.editor.x=-32000
+package.editor.y=-32000
+package.frame.height=600
+package.frame.width=800
+package.numDependencies=0
+package.numTargets=1
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.height=58
+readme.name=@README
+readme.width=47
+readme.x=10
+readme.y=10
+target1.height=50
+target1.name=CaesarCipher
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=110
+target1.x=70
+target1.y=10