3DES is a triple data encryption algorithm, which is equivalent to applying the DES encryption algorithm 3 times to each data block. Because the key length of the original DES algorithm is too short and easy to be cracked by brute force, the 3DES algorithm prevents encrypted data from being cracked by increasing the length of the key.
This algorithm is a reversible algorithm like RSA, which supports decryption of encrypted strings, provided that the key must be the same as the encryption during decryption.
Similarly, our encryption tool class should be in the java library
Des3Util.java This class is in the java library
public class Des3Util {
//定义加密算法DESede,即3DES
private static final String Algorithm = "DESede";
/**
* 加密函数，key为密钥
* @param key
* @param raw
* @return
*/
public static String encrypt(String key, String raw) {
try {
byte[] enBytes = encryptMode(key, raw.getBytes());
BASE64Encoder encoder = new BASE64Encoder();
return encoder.encode(enBytes);
} catch (Exception e) {
e.printStackTrace();
return raw;
}
}
/**
* 解密函数，key值必须和加密时的key一致
* @param key
* @param enc
* @return
*/
public static String decrypt(String key,String enc){
try {
BASE64Decoder decoder = new BASE64Decoder();
byte[] enBytes = decoder.decodeBuffer(enc);
byte[] deBytes = decryptMode(key,enBytes);
return new String(deBytes);
} catch (IOException e) {
e.printStackTrace();
return enc;
}
}
private static byte[] encryptMode(String key, byte[] src) {
try {
SecretKey deskey = new SecretKeySpec(build3Deskey(key), Algorithm);
Cipher cipher = Cipher.getInstance(Algorithm);
cipher.init(Cipher.ENCRYPT_MODE, deskey);
return cipher.doFinal(src);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return null;
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
} catch (InvalidKeyException e) {
e.printStackTrace();
return null;
} catch (BadPaddingException e) {
e.printStackTrace();
return null;
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
return null;
}
}
private static byte[] decryptMode(String key,byte[] src){
try {
SecretKey deskey = new SecretKeySpec(build3Deskey(key),Algorithm);
Cipher cipher = Cipher.getInstance(Algorithm);
cipher.init(Cipher.DECRYPT_MODE,deskey);
return cipher.doFinal(src);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return null;
} catch (NoSuchPaddingException e) {
e.printStackTrace();
return null;
} catch (InvalidKeyException e) {
e.printStackTrace();
return null;
} catch (BadPaddingException e) {
e.printStackTrace();
return null;
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
return null;
}
}
/**
* 根据字符串生成密钥24位的字节数组
*
* @param keyStr
* @return
*/
private static byte[] build3Deskey(String keyStr) {
try {
byte[] key = new byte[24];
byte[] temp = keyStr.getBytes("UTF-8");
if (key.length > temp.length) {
System.arraycopy(temp, 0, key, 0, temp.length);
} else {
System.arraycopy(temp, 0, key, 0, key.length);
}
return key;
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
return null;
}
}
}activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="5dp">
<EditText
android:id="@+id/et"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="输入文字"/>
<Button
android:id="@+id/bt_jiam"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="加密"/>
<Button
android:id="@+id/bt_jiem"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="解密"/>
<Button
android:id="@+id/bt_scmyd"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="生成密钥对"/>
</LinearLayout>MainActivity.java
public class MainActivity extends AppCompatActivity {
private EditText et;
private Button bt_jiam;
private Button bt_jiem;
private Button bt_scmyd;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et = findViewById(R.id.et);
bt_jiam = findViewById(R.id.bt_jiam);
bt_jiem = findViewById(R.id.bt_jiem);
bt_scmyd = findViewById(R.id.bt_scmyd);
bt_jiam.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//加密
String keyWord = Des3Util.encrypt("hzh", et.getText().toString());
et.setText(keyWord);
}
});
bt_jiem.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//解密
try {
String content = Des3Util.decrypt("hzh", et.getText().toString().trim());
et.setText(content);
} catch (Exception e) {
e.printStackTrace();
}
}
});
bt_scmyd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
}
}