diff --git a/.circleci/config.yml b/.circleci/config.yml
index c7ab408..532b022 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -2,9 +2,9 @@ version: 2.1
 
 
 jobs:
-  build-and-test-39: &template
+  build-and-test-310: &template
     docker:
-      - image: circleci/python:3.9
+      - image: circleci/python:3.10
     steps:
       - checkout
       - run:
@@ -25,6 +25,10 @@ jobs:
       - run:
           command: codecov
           name: Send coverage
+  build-and-test-39:
+    <<: *template
+    docker:
+      - image: circleci/python:3.9
   build-and-test-38:
     <<: *template
     docker:
@@ -40,6 +44,7 @@ jobs:
 workflows:
   main:
     jobs:
+      - build-and-test-310
       - build-and-test-39
       - build-and-test-38
       - build-and-test-37
diff --git a/README.md b/README.md
index 82fb137..a037b6b 100644
--- a/README.md
+++ b/README.md
@@ -69,6 +69,10 @@ The current development version can be found at
 
 ## History
 
+### Ver. 0.5.0 (2022-01-18)
+- Upgrade dependency (`cryptography==36.0.1`)
+- Fix file handle leakage
+
 ### Ver. 0.4.5 (2020-12-03)
 - Fix import path issue (thanks to [Gyong1211](https://github.com/Gyong1211))
 
diff --git a/pypinksign/pypinksign.py b/pypinksign/pypinksign.py
index 8a27482..2b3a11e 100644
--- a/pypinksign/pypinksign.py
+++ b/pypinksign/pypinksign.py
@@ -188,7 +188,8 @@ def _load_prikey_with_decrypted_data(self, decrypted_prikey_data: bytes) -> None
     def load_p12(self, p12_data: bytes = None) -> None:
         """Load key information from P12(PKCS12, Usually pfx)"""
         if p12_data is None:
-            p12_data = open(self.p12_path, 'rb').read()
+            with open(self.p12_path, 'rb') as f:
+                p12_data = f.read()
 
         pubkey_data, prikey_data = separate_p12_into_npki(p12_data, self.prikey_password)
         self.load_pubkey(pubkey_data=pubkey_data)
diff --git a/setup.py b/setup.py
index 8019a04..4abc32e 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 
 
 PROJECT = 'pypinksign'
-VERSION = '0.4.5'
+VERSION = '0.5.0'
 URL = 'http://github.com/bandoche/PyPinkSign'
 AUTHOR = 'Sangjun Jung'
 AUTHOR_EMAIL = 'spamcoffee+pypinksign@gmail.com'
@@ -28,9 +28,9 @@
     zip_safe=False,
     install_requires=[
         'pyasn1==0.4.8',
-        'cryptography==3.3.2',
+        'cryptography==36.0.1',
     ],
-    keywords='npki 공인인증서 korean pki certificate',
+    keywords='npki 공인인증서 공동인증서 korean pki certificate',
     platforms='OS Independent',
     classifiers=[
         'Development Status :: 4 - Beta',