Merge branch 'master' of gitea.sec.tu-bs.de:y0085044/Exercise-01

src/vigenere/vig.py

@@ -1,15 +1,20 @@
 def encrypt(key, plaintext):
-    pln_bytes = bytes(plaintext, 'UTF-8')
-    key_bytes = bytes(key, 'UTF-8')
     out = ""
-
-    for i in range(len(pln_bytes)):
-        pln_chr_index = pln_bytes[i] - 0x61
-        key_chr_index = key_bytes[i % len(key)] - 0x61
-        out_chr_index = (pln_chr_index + key_chr_index) % 26
-        out = out + chr(out_chr_index + 0x61)
+    for i in range(0, len(plaintext)):
+        out += chr(((ord(key[i % len(key)]) +
+                     ord(plaintext[i]) - (2 * 0x61)) % 26)+0x61)
     return out
 
+
+def decrypt(key, cipertext):
+    out = ""
+    for i in range(0, len(cipertext)):
+        pln = ord(cipertext[i])-(ord(key[i % len(key)]) - 0x61)
+        pln = pln + 26 if pln < 0x61 else pln
+        out += chr(pln)
+    return out
+
+
 if __name__ == "__main__":
     import argparse
     parser = argparse.ArgumentParser()
@@ -18,7 +23,18 @@ if __name__ == "__main__":
     command_group.add_argument('--encrypt', metavar='KEY')
     command_group.add_argument('--decrypt', metavar='KEY')
     parser.add_argument('--out', metavar='FILE')
-
     args = parser.parse_args()
 
-print(encrypt("bbb", "test"))
+    # strip non-alphabetic chars from file and convert to lower case
+    t = ''.join([x for x in open(args.FILE, "r").read().lower() if x.isalpha()])
+
+    if(args.encrypt != None):
+        out = encrypt(args.encrypt, t)
+
+    if(args.decrypt != None):
+        out = decrypt(args.decrypt, t)
+
+    if(args.out != None):
+        open(args.out, "w").write(out)
+    else:
+        print(out)