added lab2 q1

IS/Lab/Lab1/q6_affine_bf.py

@@ -2,21 +2,16 @@ def main():
     # Affine cipher: E(x) = (ax + b) mod 26
     # Given: "ab" -> "GL"
     # a=0, b=1 -> G=6, L=11
-    # So: 6 = (a*0 + b) mod 26 -> b = 6
-    # And: 11 = (a*1 + b) mod 26 -> 11 = (a + 6) mod 26 -> a = 5
 
     ciphertext = "XPALASXYFGFUKPXUSOGEUTKCDGEXANMGNVS"
 
-    # Try all possible values of a and b for affine cipher
     for a in range(1, 26):
-        # a must be coprime to 26
         if gcd(a, 26) != 1:
             continue
 
         for b in range(26):
-            # Check if this key produces "ab" -> "GL"
+            # if key produces "ab" -> "GL"
             if (a * 0 + b) % 26 == 6 and (a * 1 + b) % 26 == 11:
-                # Found the key, now decrypt the message
                 a_inv = mod_inverse(a, 26)
                 decrypted = ""
                 for char in ciphertext:

IS/Lab/Lab2/aes_des_bit.py

@@ -0,0 +1,33 @@
+from crypto.Cipher import DES3
+
+def des_pad(text):
+    n = len(text) % 8
+    return text + (b' ' * n)
+
+def des_128(ptext, key):
+    cipher=DES.new(key, DES.MODE_ECB)
+
+
+def des_192(ptext, key):
+
+def des_256(ptext, key):
+
+def aes_128(ptext, key):
+def aes_192(ptext, key):
+def aes_256(ptext, key):
+
+def bokeh_graph():
+
+def main():
+    print("The AES/DES Encryptor")
+    ptext = input("Enter plaintext: ")
+    key = b'input("Enter key: ")'
+    print("DES 128 Bit Cyphertext: ", des_128(ptext, key))
+    print("DES 192 Bit Cyphertext: ", des_192(ptext, key))
+    print("DES 256 Bit Cyphertext: ", des_256(ptext, key))
+    print("AES 128 Bit Cyphertext: ", aes_128(ptext, key))
+    print("AES 192 Bit Cyphertext: ", aes_192(ptext, key))
+    print("AES 256 Bit Cyphertext: ", aes_256(ptext, key))
+
+if __name__ == '__main__':
+    main()

IS/Lab/Lab2/des.py

@@ -0,0 +1,36 @@
+from Crypto.Cipher import DES
+
+def des_cipher(key):
+    return DES.new(key.encode('utf-8'), DES.MODE_ECB)
+
+def despad_ptext(text):
+    n = len(text) % 8
+    if n != 0:
+        return text + (' ' * (8 - n))
+    else:
+        return text
+
+def des_en(ptext, key):
+    cipher = des_cipher(key)
+    ptext = despad_ptext(ptext).encode('utf-8')
+    return cipher.encrypt(ptext)
+
+def des_de(ctext, key):
+    cipher = des_cipher(key)
+    return cipher.decrypt(ctext).decode('utf-8').rstrip()
+
+def despad_key(key):
+    return key.ljust(8)[:8]
+
+def main():
+    print("Welcome to DES (Original)")
+    ptext = input("Enter plaintext: ")
+    despad_ptext(ptext)
+    key = input("Enter key: ")
+    key = despad_key(key)
+    ctext = des_en(ptext, key)
+    print("Your ciphertext: ", ctext)
+    print("Your decrypted plaintext: ", des_de(ctext, key))
+
+if __name__ == '__main__':
+    main()