From 11630184a842b6e52f68b5cf9a076f6c15fd179f Mon Sep 17 00:00:00 2001
From: Gulsher Cheema <cheemgul@sheridancollege.ca>
Date: Fri, 28 Jun 2024 23:42:29 -0400
Subject: [PATCH 1/2] Completed the Playfair Cipher challenge

---
 javascript/solution.js | 114 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)

diff --git a/javascript/solution.js b/javascript/solution.js
index e69de29..ad33d70 100644
--- a/javascript/solution.js
+++ b/javascript/solution.js
@@ -0,0 +1,114 @@
+class PlayfairCipher {
+    constructor(key) {
+      this.matrix = this.generateMatrix(key);
+    }
+  
+    // Function to generate the 5x5 matrix
+    generateMatrix(key) {
+      key = key.toUpperCase().replace(/J/g, 'I');
+      const alphabet = 'ABCDEFGHIKLMNOPQRSTUVWXYZ';
+      const keyMatrix = [];
+      const usedChars = new Set();
+  
+      // Add key characters to the matrix
+      for (let char of key) {
+        if (!usedChars.has(char)) {
+          keyMatrix.push(char);
+          usedChars.add(char);
+        }
+      }
+  
+      // Add remaining alphabet characters to the matrix
+      for (let char of alphabet) {
+        if (!usedChars.has(char)) {
+          keyMatrix.push(char);
+          usedChars.add(char);
+        }
+      }
+  
+      // Create 5x5 matrix
+      const matrix = [];
+      while (keyMatrix.length) {
+        matrix.push(keyMatrix.splice(0, 5));
+      }
+  
+      return matrix;
+    }
+  
+    // Function to preprocess the input text
+    preprocessInput(text) {
+      text = text.toUpperCase().replace(/J/g, 'I').replace(/[^A-Z]/g, '');
+      const digraphs = [];
+      
+      for (let i = 0; i < text.length; i += 2) {
+        let pair = text[i];
+        if (i + 1 < text.length) {
+          if (text[i] === text[i + 1]) {
+            pair += 'X';
+          } else {
+            pair += text[i + 1];
+          }
+        } else {
+          pair += 'X';
+        }
+        digraphs.push(pair);
+      }
+  
+      return digraphs;
+    }
+  
+    // Function to find the position of a character in the matrix
+    findPosition(char) {
+      for (let row = 0; row < 5; row++) {
+        for (let col = 0; col < 5; col++) {
+          if (this.matrix[row][col] === char) {
+            return { row, col };
+          }
+        }
+      }
+    }
+  
+    // Function to decrypt a single digraph
+    decryptPair(pair) {
+      const pos1 = this.findPosition(pair[0]);
+      const pos2 = this.findPosition(pair[1]);
+      let decryptedPair = '';
+  
+      if (pos1.row === pos2.row) {
+        // Same row: shift left
+        decryptedPair += this.matrix[pos1.row][(pos1.col + 4) % 5];
+        decryptedPair += this.matrix[pos2.row][(pos2.col + 4) % 5];
+      } else if (pos1.col === pos2.col) {
+        // Same column: shift up
+        decryptedPair += this.matrix[(pos1.row + 4) % 5][pos1.col];
+        decryptedPair += this.matrix[(pos2.row + 4) % 5][pos2.col];
+      } else {
+        // Rectangle swap
+        decryptedPair += this.matrix[pos1.row][pos2.col];
+        decryptedPair += this.matrix[pos2.row][pos1.col];
+      }
+  
+      return decryptedPair;
+    }
+  
+    // Main decryption function
+    decrypt(ciphertext) {
+      const digraphs = this.preprocessInput(ciphertext);
+      let plaintext = '';
+  
+      for (let digraph of digraphs) {
+        plaintext += this.decryptPair(digraph);
+      }
+  
+      return plaintext;
+    }
+  }
+  
+  const key = "SUPERSPY";
+  const ciphertext = "IKEWENENXLNQLPZSLERUMRHEERYBOFNEINCHCV";
+  
+  const playfair = new PlayfairCipher(key);
+  const plaintext = playfair.decrypt(ciphertext);
+  
+  console.log("Decrypted message:", plaintext);
+  
\ No newline at end of file

From 8afadcae8cb0ffba2c11fbd2eb2c1f5acdca375c Mon Sep 17 00:00:00 2001
From: Gulsher Cheema <cheemgul@sheridancollege.ca>
Date: Fri, 28 Jun 2024 23:54:30 -0400
Subject: [PATCH 2/2] Made necessary changes to the Playfair Cipher solution

---
 javascript/solution.js | 204 +++++++++++++++++++++--------------------
 1 file changed, 104 insertions(+), 100 deletions(-)

diff --git a/javascript/solution.js b/javascript/solution.js
index ad33d70..23f46c8 100644
--- a/javascript/solution.js
+++ b/javascript/solution.js
@@ -1,114 +1,118 @@
 class PlayfairCipher {
-    constructor(key) {
-      this.matrix = this.generateMatrix(key);
-    }
-  
-    // Function to generate the 5x5 matrix
-    generateMatrix(key) {
-      key = key.toUpperCase().replace(/J/g, 'I');
-      const alphabet = 'ABCDEFGHIKLMNOPQRSTUVWXYZ';
-      const keyMatrix = [];
-      const usedChars = new Set();
-  
-      // Add key characters to the matrix
-      for (let char of key) {
-        if (!usedChars.has(char)) {
-          keyMatrix.push(char);
-          usedChars.add(char);
-        }
-      }
-  
-      // Add remaining alphabet characters to the matrix
-      for (let char of alphabet) {
-        if (!usedChars.has(char)) {
-          keyMatrix.push(char);
-          usedChars.add(char);
-        }
+  constructor(key) {
+    this.matrix = this.generateMatrix(key);
+  }
+
+  // Function to generate the 5x5 matrix
+  generateMatrix(key) {
+    key = key.toUpperCase().replace(/J/g, 'I');
+    const alphabet = 'ABCDEFGHIKLMNOPQRSTUVWXYZ';
+    const keyMatrix = [];
+    const usedChars = new Set();
+
+    // Add key characters to the matrix
+    for (let char of key) {
+      if (!usedChars.has(char)) {
+        keyMatrix.push(char);
+        usedChars.add(char);
       }
-  
-      // Create 5x5 matrix
-      const matrix = [];
-      while (keyMatrix.length) {
-        matrix.push(keyMatrix.splice(0, 5));
+    }
+
+    // Add remaining alphabet characters to the matrix
+    for (let char of alphabet) {
+      if (!usedChars.has(char)) {
+        keyMatrix.push(char);
+        usedChars.add(char);
       }
-  
-      return matrix;
     }
-  
-    // Function to preprocess the input text
-    preprocessInput(text) {
-      text = text.toUpperCase().replace(/J/g, 'I').replace(/[^A-Z]/g, '');
-      const digraphs = [];
-      
-      for (let i = 0; i < text.length; i += 2) {
-        let pair = text[i];
-        if (i + 1 < text.length) {
-          if (text[i] === text[i + 1]) {
-            pair += 'X';
-          } else {
-            pair += text[i + 1];
-          }
-        } else {
+
+    // Create 5x5 matrix
+    const matrix = [];
+    while (keyMatrix.length) {
+      matrix.push(keyMatrix.splice(0, 5));
+    }
+
+    return matrix;
+  }
+
+  // Function to preprocess the input text
+  preprocessInput(text) {
+    text = text.toUpperCase().replace(/J/g, 'I').replace(/[^A-Z]/g, '');
+    const digraphs = [];
+    
+    for (let i = 0; i < text.length; i += 2) {
+      let pair = text[i];
+      if (i + 1 < text.length) {
+        if (text[i] === text[i + 1]) {
           pair += 'X';
+        } else {
+          pair += text[i + 1];
         }
-        digraphs.push(pair);
+      } else {
+        pair += 'X';
       }
-  
-      return digraphs;
+      digraphs.push(pair);
     }
-  
-    // Function to find the position of a character in the matrix
-    findPosition(char) {
-      for (let row = 0; row < 5; row++) {
-        for (let col = 0; col < 5; col++) {
-          if (this.matrix[row][col] === char) {
-            return { row, col };
-          }
+
+    return digraphs;
+  }
+
+  // Function to find the position of a character in the matrix
+  findPosition(char) {
+    for (let row = 0; row < 5; row++) {
+      for (let col = 0; col < 5; col++) {
+        if (this.matrix[row][col] === char) {
+          return { row, col };
         }
       }
     }
-  
-    // Function to decrypt a single digraph
-    decryptPair(pair) {
-      const pos1 = this.findPosition(pair[0]);
-      const pos2 = this.findPosition(pair[1]);
-      let decryptedPair = '';
-  
-      if (pos1.row === pos2.row) {
-        // Same row: shift left
-        decryptedPair += this.matrix[pos1.row][(pos1.col + 4) % 5];
-        decryptedPair += this.matrix[pos2.row][(pos2.col + 4) % 5];
-      } else if (pos1.col === pos2.col) {
-        // Same column: shift up
-        decryptedPair += this.matrix[(pos1.row + 4) % 5][pos1.col];
-        decryptedPair += this.matrix[(pos2.row + 4) % 5][pos2.col];
-      } else {
-        // Rectangle swap
-        decryptedPair += this.matrix[pos1.row][pos2.col];
-        decryptedPair += this.matrix[pos2.row][pos1.col];
-      }
-  
-      return decryptedPair;
+  }
+
+  // Function to decrypt a single digraph
+  decryptPair(pair) {
+    const pos1 = this.findPosition(pair[0]);
+    const pos2 = this.findPosition(pair[1]);
+    let decryptedPair = '';
+
+    if (pos1.row === pos2.row) {
+      // Same row: shift left
+      decryptedPair += this.matrix[pos1.row][(pos1.col + 4) % 5];
+      decryptedPair += this.matrix[pos2.row][(pos2.col + 4) % 5];
+    } else if (pos1.col === pos2.col) {
+      // Same column: shift up
+      decryptedPair += this.matrix[(pos1.row + 4) % 5][pos1.col];
+      decryptedPair += this.matrix[(pos2.row + 4) % 5][pos2.col];
+    } else {
+      // Rectangle swap
+      decryptedPair += this.matrix[pos1.row][pos2.col];
+      decryptedPair += this.matrix[pos2.row][pos1.col];
     }
-  
-    // Main decryption function
-    decrypt(ciphertext) {
-      const digraphs = this.preprocessInput(ciphertext);
-      let plaintext = '';
-  
-      for (let digraph of digraphs) {
-        plaintext += this.decryptPair(digraph);
-      }
-  
-      return plaintext;
+
+    return decryptedPair;
+  }
+
+  // Main decryption function
+  decrypt(ciphertext) {
+    const digraphs = this.preprocessInput(ciphertext);
+    let plaintext = '';
+
+    for (let digraph of digraphs) {
+      plaintext += this.decryptPair(digraph);
     }
+
+    // Remove padding 'X' and ensure uppercase output without spaces or special characters
+    plaintext = plaintext.replace(/X/g, '');
+    plaintext = plaintext.replace(/[^A-Z]/g, '');
+
+    return plaintext.toUpperCase();
   }
-  
-  const key = "SUPERSPY";
-  const ciphertext = "IKEWENENXLNQLPZSLERUMRHEERYBOFNEINCHCV";
-  
-  const playfair = new PlayfairCipher(key);
-  const plaintext = playfair.decrypt(ciphertext);
-  
-  console.log("Decrypted message:", plaintext);
-  
\ No newline at end of file
+}
+
+// Example usage
+const key = "SUPERSPY";
+const ciphertext = "IKEWENENXLNQLPZSLERUMRHEERYBOFNEINCHCV";
+
+const playfair = new PlayfairCipher(key);
+const plaintext = playfair.decrypt(ciphertext);
+
+console.log("Decrypted message:", plaintext);