homework01 complete

.github/workflows/cs102.yml

@@ -7,10 +7,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python 3.8.6
+    - name: Set up Python 3.10
       uses: actions/setup-python@v2
       with:
-        python-version: '3.8.6'
+        python-version: '3.10'
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

homework01/caesar.py

@@ -15,7 +15,14 @@ def encrypt_caesar(plaintext: str, shift: int = 3) -> str:
     ''
     """
     ciphertext = ""
-    # PUT YOUR CODE HERE
+    for i in plaintext:
+        if i.isalpha():
+            if i.isupper():
+                ciphertext += chr((ord(i) - 65 + shift) % 26 + 65)
+            else:
+                ciphertext += chr((ord(i) - 97 + shift) % 26 + 97)
+        else:
+            ciphertext += i
     return ciphertext
 
 
@@ -33,7 +40,14 @@ def decrypt_caesar(ciphertext: str, shift: int = 3) -> str:
     ''
     """
     plaintext = ""
-    # PUT YOUR CODE HERE
+    for i in ciphertext:
+        if i.isalpha():
+            if i.isupper():
+                plaintext += chr((ord(i) - 65 - shift) % 26 + 65)
+            else:
+                plaintext += chr((ord(i) - 97 - shift) % 26 + 97)
+        else:
+            plaintext += i
     return plaintext
 
 

homework01/rsa.py

@@ -13,8 +13,13 @@ def is_prime(n: int) -> bool:
     >>> is_prime(8)
     False
     """
-    # PUT YOUR CODE HERE
-    pass
+    if n <= 1:
+        return False
+    else:
+        for i in range(2, int(n**0.5) + 1):
+            if n % i == 0:
+                return False
+        return True
 
 
 def gcd(a: int, b: int) -> int:
@@ -26,8 +31,12 @@ def gcd(a: int, b: int) -> int:
     >>> gcd(3, 7)
     1
     """
-    # PUT YOUR CODE HERE
-    pass
+    while a > 0 and b > 0:
+        if a > b:
+            a %= b
+        else:
+            b %= a
+    return a + b
 
 
 def multiplicative_inverse(e: int, phi: int) -> int:
@@ -38,8 +47,16 @@ def multiplicative_inverse(e: int, phi: int) -> int:
     >>> multiplicative_inverse(7, 40)
     23
     """
-    # PUT YOUR CODE HERE
-    pass
+
+    def gcd_extended(e, phi):
+        if e != 0:
+            div, x, y = gcd_extended(phi % e, e)
+        else:
+            return phi, 0, 1
+        return div, y - (phi // e) * x, x
+
+    a = gcd_extended(e, phi)
+    return a[1] % phi
 
 
 def generate_keypair(p: int, q: int) -> tp.Tuple[tp.Tuple[int, int], tp.Tuple[int, int]]:
@@ -49,10 +66,10 @@ def generate_keypair(p: int, q: int) -> tp.Tuple[tp.Tuple[int, int], tp.Tuple[in
         raise ValueError("p and q cannot be equal")
 
     # n = pq
-    # PUT YOUR CODE HERE
+    n = p * q
 
     # phi = (p-1)(q-1)
-    # PUT YOUR CODE HERE
+    phi = (p - 1) * (q - 1)
 
     # Choose an integer e such that e and phi(n) are coprime
     e = random.randrange(1, phi)
@@ -85,7 +102,7 @@ def decrypt(pk: tp.Tuple[int, int], ciphertext: tp.List[int]) -> str:
     # Unpack the key into its components
     key, n = pk
     # Generate the plaintext based on the ciphertext and key using a^b mod m
-    plain = [chr((char ** key) % n) for char in ciphertext]
+    plain = [chr((char**key) % n) for char in ciphertext]
     # Return the array of bytes as a string
     return "".join(plain)
 

homework01/vigenere.py

@@ -10,7 +10,15 @@ def encrypt_vigenere(plaintext: str, keyword: str) -> str:
     'LXFOPVEFRNHR'
     """
     ciphertext = ""
-    # PUT YOUR CODE HERE
+    for j in range(len(plaintext)):
+        i = plaintext[j]
+        if i.isalpha():
+            if i.isupper():
+                ciphertext += chr((ord(i) + ord(keyword[j % len(keyword)]) - 130) % 26 + 65)
+            else:
+                ciphertext += chr((ord(i) + ord(keyword[j % len(keyword)]) - 194) % 26 + 97)
+        else:
+            ciphertext += i
     return ciphertext
 
 
@@ -26,5 +34,13 @@ def decrypt_vigenere(ciphertext: str, keyword: str) -> str:
     'ATTACKATDAWN'
     """
     plaintext = ""
-    # PUT YOUR CODE HERE
+    for j in range(len(ciphertext)):
+        i = ciphertext[j]
+        if i.isalpha():
+            if i.isupper():
+                plaintext += chr((ord(i) - ord(keyword[j % len(keyword)])) % 26 + 65)
+            else:
+                plaintext += chr((ord(i) - ord(keyword[j % len(keyword)])) % 26 + 97)
+        else:
+            plaintext += i
     return plaintext