Assignment2

Assignment_2- Affine cipher.py

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+import math
+
+def gcd(a, b):
+    while b != 0:
+        a, b = b, a % b
+    return a
+
+def mod_inverse(a, m):
+    a = a % m
+    for x in range(1, m):
+        if (a * x) % m == 1:
+            return x
+    return None  # No inverse exists
+
+def affine_encrypt(text, a, b):
+    result = []
+    for char in text:
+        if char.isalpha():
+            base = ord('A') if char.isupper() else ord('a')
+            x = ord(char) - base
+            y = (a * x + b) % 26
+            result.append(chr(y + base))
+        else:
+            result.append(char)  # Non-alphabetic characters unchanged
+    return ''.join(result)
+
+def affine_decrypt(text, a, b):
+    a_inv = mod_inverse(a, 26)
+    if a_inv is None:
+        raise ValueError("Key 'a' has no modular inverse. Choose a different key.")
+
+    result = []
+    for char in text:
+        if char.isalpha():
+            base = ord('A') if char.isupper() else ord('a')
+            y = ord(char) - base
+            x = (a_inv * (y - b)) % 26
+            result.append(chr(x + base))
+        else:
+            result.append(char)  # Non-alphabetic characters unchanged
+    return ''.join(result)
+
+def main():
+    print("Affine Cipher")
+    choice = input("1. Encrypt\n2. Decrypt\nEnter choice (1/2): ")
+    text = input("Enter text: ")
+    a = int(input("Enter key 'a' (must be coprime with 26): "))
+    b = int(input("Enter key 'b': "))
+
+    if gcd(a, 26) != 1:
+        print("Error: 'a' must be coprime with 26 (valid keys: 1,3,5,7,9,11,15,17,19,21,23,25).")
+        return
+
+    if choice == '1':
+        ciphertext = affine_encrypt(text, a, b)
+        print(f"Encrypted: {ciphertext}")
+    elif choice == '2':
+        try:
+            plaintext = affine_decrypt(text, a, b)
+            print(f"Decrypted: {plaintext}")
+        except ValueError as e:
+            print(e)
+    else:
+        print("Invalid choice.")
+
+if __name__ == "__main__":
+    main()

cool_amur1.ino

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+// C++ code
+//
+const int pot1Pin = A0;
+const int pot2Pin = A1;
+const int buzzerPins[3] = {3, 4, 5};        // Buzzer 1, 2, 3
+const int ledPins[5] = {6, 7, 8, 9, 10};    // LED sequence
+void setup()
+{
+   for (int i = 0; i < 3; i++) {
+    pinMode(buzzerPins[i], OUTPUT);
+  }
+
+  for (int i = 0; i < 5; i++) {
+    pinMode(ledPins[i], OUTPUT);
+  }
+}
+
+void loop()
+{
+  // --- POT1: Buzzer Control ---
+  int pot1Value = analogRead(pot1Pin);
+
+  // Turn off all buzzers first
+  for (int i = 0; i < 3; i++) {
+    digitalWrite(buzzerPins[i], LOW);
+  }
+
+  // Activate buzzer based on value range
+  if (pot1Value <= 341) {
+    digitalWrite(buzzerPins[0], HIGH);
+  } else if (pot1Value <= 682) {
+    digitalWrite(buzzerPins[1], HIGH);
+  } else {
+    digitalWrite(buzzerPins[2], HIGH);
+  }
+
+
+  // --- POT2: LED Sequence Speed Control ---
+  int pot2Value = analogRead(pot2Pin);
+
+  // Map analog value to delay (e.g., 50 to 1000 ms)
+  int delayTime = map(pot2Value, 0, 1023, 50, 1000);
+
+  // Light up one LED at a time
+  for (int i = 0; i < 5; i++) {
+    for (int j = 0; j < 5; j++) {
+      digitalWrite(ledPins[j], (i == j) ? HIGH : LOW);
+    }
+    delay(delayTime);
+  }
+}