Cyber-Security-project/cipher.js at main · codeByHelal/Cyber-Security-project · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
// Additive Cipher (Caesar Cipher)
function encryptAdditive() {
  var message = document.getElementById("additive-message").value.toLowerCase();
  var key = parseInt(document.getElementById("additive-key").value);
  var encrypted = "";
  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var code = char.charCodeAt(0);
      var encryptedCode = (code - 'a'.charCodeAt(0) + key) % 26 + 'a'.charCodeAt(0);
      encrypted += String.fromCharCode(encryptedCode);
    } else {
      encrypted += char;
    }
  }
  document.getElementById("additive-result").value = encrypted;
}

function decryptAdditive() {
  var message = document.getElementById("additive-message").value.toLowerCase();
  var key = parseInt(document.getElementById("additive-key").value);
  var decrypted = "";
  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var code = char.charCodeAt(0);
      var decryptedCode = (code - 'a'.charCodeAt(0) - key + 26) % 26 + 'a'.charCodeAt(0);
      decrypted += String.fromCharCode(decryptedCode);
    } else {
      decrypted += char;
    }
  }
  document.getElementById("additive-result").value = decrypted;
}

// Multiplicative Cipher

function findMultiplicativeInverse(key) {
  for (var i = 1; i < 26; i++) {
    if ((key * i) % 26 === 1) {
      return i;
    }
  }
  return -1; // No inverse exists
}

function encryptMultiplicative() {
  var message = document.getElementById("multiplicative-message").value.toLowerCase();
  var key = parseInt(document.getElementById("multiplicative-key").value);
  var encrypted = "";

  if (findMultiplicativeInverse(key) === -1) {
    document.getElementById("multiplicative-result").value = "Invalid key: No multiplicative inverse exits of your key!";
    return;
  }

  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var code = char.charCodeAt(0) - 'a'.charCodeAt(0);
      var encryptedCode = ((code * key) % 26) + 'a'.charCodeAt(0);
      encrypted += String.fromCharCode(encryptedCode);
    } else {
      encrypted += char;
    }
  }
  document.getElementById("multiplicative-result").value = encrypted;
}

function decryptMultiplicative() {
  var message = document.getElementById("multiplicative-message").value.toLowerCase();
  var key = parseInt(document.getElementById("multiplicative-key").value);
  var decrypted = "";

  var modInverse = findMultiplicativeInverse(key);
  if (modInverse === -1) {
    document.getElementById("multiplicative-result").value = "Invalid key: No multiplicative inverse exits of your key!";
    return;
  }

  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var code = char.charCodeAt(0) - 'a'.charCodeAt(0);
      var decryptedCode = ((code * modInverse) % 26) + 'a'.charCodeAt(0);
      decrypted += String.fromCharCode(decryptedCode);
    } else {
      decrypted += char;
    }
  }
  document.getElementById("multiplicative-result").value = decrypted;
}


// Affine Cipher
function encryptAffine() {
  var message = document.getElementById("affine-message").value.toLowerCase();
  var keyA = parseInt(document.getElementById("affine-key-a").value);
  var keyB = parseInt(document.getElementById("affine-key-b").value);
  var encrypted = "";
  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var code = char.charCodeAt(0);
      var encryptedCode = (keyA * (code - 'a'.charCodeAt(0)) + keyB) % 26 + 'a'.charCodeAt(0);
      encrypted += String.fromCharCode(encryptedCode);
    } else {
      encrypted += char;
    }
  }
  document.getElementById("affine-result").value = encrypted;
}

function decryptAffine() {
  var message = document.getElementById("affine-message").value.toLowerCase();
  var keyA = parseInt(document.getElementById("affine-key-a").value);
  var keyB = parseInt(document.getElementById("affine-key-b").value);
  var modInverse = 0;
  for (var i = 0; i < 26; i++) {
    if ((keyA * i) % 26 === 1) {
      modInverse = i;
      break;
    }
  }
  var decrypted = "";
  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var code = char.charCodeAt(0);
      var decryptedCode = modInverse * (code - 'a'.charCodeAt(0) - keyB + 26) % 26 + 'a'.charCodeAt(0);
      decrypted += String.fromCharCode(decryptedCode);
    } else {
      decrypted += char;
    }
  }
  document.getElementById("affine-result").value = decrypted;
}

// Monoalphabetic Substitution Cipher
function encryptMono() {
  var message = document.getElementById("mono-message").value.toLowerCase();
  var key = document.getElementById("mono-key").value.toLowerCase();
  var encrypted = "";
  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var index = char.charCodeAt(0) - 'a'.charCodeAt(0);
      encrypted += key[index];
    } else {
      encrypted += char;
    }
  }
  document.getElementById("mono-result").value = encrypted;
}

function decryptMono() {
  var message = document.getElementById("mono-message").value.toLowerCase();
  var key = document.getElementById("mono-key").value.toLowerCase();
  var decrypted = "";
  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    var index = key.indexOf(char);
    if (index !== -1) {
      decrypted += String.fromCharCode(index + 'a'.charCodeAt(0));
    } else {
      decrypted += char;
    }
  }
  document.getElementById("mono-result").value = decrypted;
}

// Vigenère Cipher (Polyalphabetic Substitution Cipher)
function encryptVigenere() {
  var message = document.getElementById("vigenere-message").value.toLowerCase();
  var key = document.getElementById("vigenere-key").value.toLowerCase();
  var keyIndex = 0;
  var encrypted = "";
  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var shift = key[keyIndex].charCodeAt(0) - 'a'.charCodeAt(0);
      var code = (char.charCodeAt(0) + shift - 'a'.charCodeAt(0)) % 26 + 'a'.charCodeAt(0);
      encrypted += String.fromCharCode(code);
      keyIndex = (keyIndex + 1) % key.length;
    } else {
      encrypted += char;
    }
  }
  document.getElementById("vigenere-result").value = encrypted;
}

function decryptVigenere() {
  var message = document.getElementById("vigenere-message").value.toLowerCase();
  var key = document.getElementById("vigenere-key").value.toLowerCase();
  var keyIndex = 0;
  var decrypted = "";
  for (var i = 0; i < message.length; i++) {
    var char = message[i];
    if (char >= 'a' && char <= 'z') {
      var shift = key[keyIndex].charCodeAt(0) - 'a'.charCodeAt(0);
      var code = (char.charCodeAt(0) - shift - 'a'.charCodeAt(0) + 26) % 26 + 'a'.charCodeAt(0);
      decrypted += String.fromCharCode(code);
      keyIndex = (keyIndex + 1) % key.length;
    } else {
      decrypted += char;
    }
  }
  document.getElementById("vigenere-result").value = decrypted;
}