diff --git a/README.md b/README.md
index 2ca1629..a399627 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ JAVA 1.8버전 사용자들을 위한 세션키 발급 및 개인정보 암복
 
 예시)
 ```
-<version>0.0.5</version>
+<version>0.0.6</version>
 ```
 
 pom.xml 을 사용하시면 아래와 같이 추가해주세요.
diff --git a/build.gradle b/build.gradle
index a223508..4030ae7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -6,7 +6,7 @@ plugins {
 }
 
 group 'com.github.toss'
-version '0.0.5'
+version '0.0.6'
 
 sourceCompatibility = JavaVersion.VERSION_1_6
 targetCompatibility = JavaVersion.VERSION_1_6
diff --git a/src/main/java/im/toss/cert/sdk/AESCipher.java b/src/main/java/im/toss/cert/sdk/AESCipher.java
index 03d8f08..86b9110 100644
--- a/src/main/java/im/toss/cert/sdk/AESCipher.java
+++ b/src/main/java/im/toss/cert/sdk/AESCipher.java
@@ -7,13 +7,14 @@
 import javax.crypto.spec.GCMParameterSpec;
 import javax.crypto.spec.IvParameterSpec;
 import javax.crypto.spec.SecretKeySpec;
-import java.nio.charset.StandardCharsets;
+import java.nio.charset.Charset;
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
 import java.security.spec.AlgorithmParameterSpec;
 
 class AESCipher {
+    private static final Charset charset = Charset.forName("UTF-8");
     private final SecretKeySpec secretKey;
     private final AlgorithmParameterSpec ivSpec;
     private final AESAlgorithm algorithm;
@@ -34,14 +35,14 @@ class AESCipher {
 
     String encrypt(String plainText) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
         Cipher cipher = getCipher(Cipher.ENCRYPT_MODE);
-        byte[] cipherText = cipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8));
+        byte[] cipherText = cipher.doFinal(plainText.getBytes(charset));
         return Base64Utils.encodeToString(cipherText);
     }
 
     String decrypt(String encryptedText) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
         Cipher cipher = getCipher(Cipher.DECRYPT_MODE);
         byte[] cipherText = cipher.doFinal(Base64Utils.decode(encryptedText));
-        return new String(cipherText, StandardCharsets.UTF_8);
+        return new String(cipherText, charset);
     }
 
     private Cipher getCipher(int opMode) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException {