Adding vigenere cipher script

vigenere_cipher/README.md

@@ -0,0 +1,17 @@
+# Vigenère cipher
+
+Python script that encrypts/decrypts a given text with a given key based on the [Vigenere cipher](https://en.wikipedia.org/wiki/Vigenère_cipher)
+
+# Usage
+
+For Windows users:
+
+```bash
+$ python vigenere.py
+```
+
+For Mac/Linux/Unix users:
+
+```bash
+$ ./vigenere.py
+```

vigenere_cipher/vigenere.py

@@ -0,0 +1,75 @@
+alph = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+
+#actuall stuff
+def decryption(key, text):
+    key_len = len(key)
+    count = 0
+    #adjusting the key
+    real_key = ''
+    #fixing spaces
+    for i in text:
+        if i != ' ':
+            if count == len(key):
+                count = 0
+            real_key += key[count]
+            count += 1
+        else:
+            real_key += ' '
+    print(real_key)
+    encr = ''
+    #decrypting
+    for c in range(0,len(text)):
+        if text[c] == ' ':
+            encr += ' '
+        else:
+            encr += (alph[(ord(text[c]) - ord(real_key[c])) % 26])
+    return encr
+
+def encryption(key, text):
+    key_len = len(key)
+    count = 0
+    #adjusting the key
+    real_key = ''
+    #fixing spaces
+    for i in text:
+        if i != ' ':
+            if count == len(key):
+                count = 0
+            real_key += key[count]
+            count += 1
+            
+        else:
+            real_key += ' '
+    print(real_key)
+    encr = ''
+    #encrypting
+    for c in range(0,len(text)):
+        if text[c] == ' ':
+            encr += ' '
+        else:
+            encr += (alph[(ord(real_key[c]) + ord(text[c])) % 26])
+    return encr
+
+#user input
+def main():
+    boolean = True
+    while(boolean):
+        try:
+            mode = input('Do you want to encrypt or to decrypt [e/d]? ')
+            if mode.upper().startswith('E'):
+                text = input('Please enter the text: ').upper()
+                key = input('Please enter the key: ').upper()
+                print(encryption(key, text))
+                boolean = False
+            elif mode.upper().startswith('D'):
+                text = input('Please enter the text: ').upper()
+                key = input('Please enter the key: ').upper()
+                print(decryption(key, text))
+                boolean = False
+            else:
+                print('Please enter a valid choice')
+        except KeyboardInterrupt:
+            exit()
+    
+if __name__ == '__main__':
+    main()