clicada/crypt.py

@@ -0,0 +1,38 @@
+# standard imports
+import os
+import logging
+
+from Crypto.Cipher import AES
+from Crypto.Util import Counter
+
+logg = logging.getLogger(__name__)
+
+
+class Encrypt:
+
+    aesBlockSize = 1 << 7
+
+    def __init__(self, secret, db_dir):
+        fp = os.path.join(db_dir, '.aes_ctr_iv')
+        try:
+            f = open(fp, 'rb')
+            self.iv = f.read()
+        except FileNotFoundError:
+            logg.debug('generating new iv for aes-ctr')
+            self.iv = os.urandom(8)
+            f = open(fp, 'wb')
+            f.write(self.iv)
+
+        f.close()
+
+        iv_num = int.from_bytes(self.iv, 'big')
+        self.ctr = Counter.new(aesBlockSize, initial_value=iv_num)
+        self.cipher = AES.new(secret, AES.MODE_CTR, counter=self.ctr)
+
+
+    def encrypt(self, v):
+        return self.cipher.encrypt(v)
+       
+
+    def decrypt(self, v):
+        return self.cipher.decrypt(v)