【框架】加密解密

共四种：

1.base64（大小写英文字母、10个基本阿拉伯数字、+、/）

2.MD5(任意长度的数据，算出的MD5值长度都是固定的，哪怕只修改1个字节，所得到的MD5值都有很大区别)

3.对称密钥加密（加密解密的密钥一样）

4.非对称加密（加密解密的密钥不一样，分为公钥和私钥）

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
NavigationView navigationView = (NavigationView) findViewById(R.id.navigation_view);
final DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(MenuItem item) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
switch (item.getItemId()) {
case R.id.base64:
//                        fragment = new Base64Fragment();
transaction.replace(R.id.content, new Base64Fragment());
break;
case R.id.md5:
transaction.replace(R.id.content, new MD5Fragment());
break;
case R.id.des:
transaction.replace(R.id.content, new DESFragment());
break;
case R.id.rsa:
transaction.replace(R.id.content, new RSAFragment());
break;
}
//                transaction.replace(R.id.content, fragment).commit();
transaction.commit();
drawerLayout.closeDrawer(Gravity.LEFT);
return true;
}
});
}
}

Base64加密解密

public class Base64Fragment extends Fragment {
@Bind(R.id.encode_et)
EditText encodeEt;
@Bind(R.id.decode_et)
EditText decodeEt;
@Bind(R.id.result)
TextView result;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.base64_layout,null);
ButterKnife.bind(this, view);
return view;
}

@OnClick(R.id.encode)
public void encode() {
String srcStr = encodeEt.getText().toString();
//编码
String s = Base64.encodeToString(srcStr.getBytes(), Base64.DEFAULT);
decodeEt.setText(s);
}

@OnClick(R.id.decode)
public void decode() {
String srcStr = decodeEt.getText().toString();
byte[] decode = Base64.decode(srcStr.getBytes(), Base64.DEFAULT);
String s = new String(decode, 0, decode.length);
result.setText(s);
}
}

MD5加密解密

public class MD5Fragment extends Fragment {
@Bind(R.id.encode_et)
EditText encodeEt;
@Bind(R.id.result)
TextView result;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.md5_layout, null);
ButterKnife.bind(this, view);
return view;
}

@OnClick(R.id.encode)
public void encode() {
try {
//获取一个消息摘要生成实例
MessageDigest messageDigest = MessageDigest.getInstance("MD5");
byte[] digest = messageDigest.digest(encodeEt.getText().toString().getBytes());
StringBuffer stringBuffer = new StringBuffer();
for (byte b : digest) {
//使用十六进制输出消息摘要，不足两位的用0补齐
stringBuffer.append(String.format("%02x", b));
}
result.setText(stringBuffer.toString());
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
}
}

对称密钥加密

public class DESFragment extends Fragment {
@Bind(R.id.encode_et)
EditText encodeEt;
@Bind(R.id.decode_et)
EditText decodeEt;
@Bind(R.id.encode_et2)
EditText encodeEt2;
@Bind(R.id.decode_et2)
EditText decodeEt2;
@Bind(R.id.encode_et3)
EditText encodeEt3;
@Bind(R.id.decode_et3)
EditText decodeEt3;
@Bind(R.id.result)
TextView result;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.des_layout, null);
ButterKnife.bind(this, view);
return view;
}

@OnClick(R.id.encode)
public void encode() {
String des = EncryptionHelper.des(encodeEt.getText().toString(), "789", EncryptionHelper.ENCODE);
decodeEt.setText(des);
}

@OnClick(R.id.decode)
public void decode() {
String des = EncryptionHelper.des(decodeEt.getText().toString(), "789", EncryptionHelper.DECODE);
result.setText(des);
}

@OnClick(R.id.encode2)
public void encode2() {
String s = EncryptionHelper.des3(encodeEt2.getText().toString(), "123", EncryptionHelper.ENCODE);
decodeEt2.setText(s);
}

@OnClick(R.id.decode2)
public void decode2() {
String s = EncryptionHelper.des3(decodeEt2.getText().toString(), "123", EncryptionHelper.DECODE);
result.setText(s);
}

@OnClick(R.id.encode3)
public void encode3() {
String s = EncryptionHelper.aes(encodeEt3.getText().toString(), "abcd", EncryptionHelper.ENCODE);
decodeEt3.setText(s);
}

@OnClick(R.id.decode3)
public void decode3() {
String abcd = EncryptionHelper.aes(decodeEt3.getText().toString(), "abcd", EncryptionHelper.DECODE);
result.setText(abcd);
}
}

public class EncryptionHelper {
public static final int ENCODE = 0;
public static final int DECODE = 1;

/**
* 使用DES算法进行对称加/解密
*
* @param srcStr 明文
* @param key    密钥
* @param mode   模式（加密/解密）
* @return
*/
public static String des(String srcStr, String key, int mode) {
String charsetName = "UTF-8";
try {
//获得key的byte数组
byte[] keyBytes = key.getBytes(charsetName);
//des算法中key的长度为8
byte[] temp = new byte[8];
//数组拷贝
//1.源数组
//2.开始复制的位置
//3.目标数组
//4.目标数组的位置
//5.复制的长度
System.arraycopy(keyBytes, 0, temp, 0, Math.min(keyBytes.length, temp.length));
//生成密钥
//1.密钥数组
//2.生成密钥的算法名称
SecretKey secretKey = new SecretKeySpec(temp, "des");
//获取一个密文生成器
Cipher cipher = Cipher.getInstance("des");
//如果要进行加密
if (mode == ENCODE) {
//初始化密文生成器
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
//执行加密
byte[] bytes = cipher.doFinal(srcStr.getBytes(charsetName));
//使用Base64对加密结果进行编码
String s = Base64.encodeToString(bytes, Base64.DEFAULT);
return s;
//如果要解密
} else {
//初始化密文生成器
cipher.init(Cipher.DECRYPT_MODE, secretKey);
//由于传进来的srcStr是对密文进行加密后的字符串，所以在解密之前先要解码
byte[] bytes = cipher.doFinal(Base64.decode(srcStr, Base64.DEFAULT));
//返回明文
return new String(bytes, 0, bytes.length);
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
}
return null;
}

public static String des3(String srcStr, String key, int mode) {
String charsetName = "UTF-8";
try {
byte[] keyBytes = key.getBytes(charsetName);
//注意和des算法key的长度不同
byte[] temp = new byte[24];
System.arraycopy(keyBytes, 0, temp, 0, Math.min(keyBytes.length, temp.length));
SecretKey secretKey = new SecretKeySpec(temp, "desede");
Cipher cipher = Cipher.getInstance("desede");
if (mode == ENCODE) {
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
byte[] bytes = cipher.doFinal(srcStr.getBytes(charsetName));
return Base64.encodeToString(bytes, Base64.DEFAULT);
} else {
cipher.init(Cipher.DECRYPT_MODE, secretKey);
byte[] bytes = cipher.doFinal(Base64.decode(srcStr, Base64.DEFAULT));
return new String(bytes, 0, bytes.length);
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
}
return null;
}

public static String aes(String srcStr, String key, int mode) {
String charsetName = "UTF-8";
try {
byte[] keyBytes = key.getBytes(charsetName);
byte[] temp = new byte[32];
System.arraycopy(keyBytes, 0, temp, 0, Math.min(keyBytes.length, temp.length));
SecretKey secretKey = new SecretKeySpec(temp, "aes");
Cipher cipher = Cipher.getInstance("aes");
if (mode == ENCODE) {
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
byte[] bytes = cipher.doFinal(srcStr.getBytes(charsetName));
return Base64.encodeToString(bytes, Base64.DEFAULT);
} else {
cipher.init(Cipher.DECRYPT_MODE, secretKey);
byte[] bytes = cipher.doFinal(Base64.decode(srcStr, Base64.DEFAULT));
return new String(bytes, 0, bytes.length);
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
}
return null;
}
}

非对称密钥加密

public class RSAFragment extends Fragment {
//两个大素数的乘积
private static final String MODULUS = "100631058000714094813874361191853577129731636346684218206605779824931626830750623070803100189781211343851763275329364056640619755337779928985272486091431384128027213365372009648233171894708338213168824861061809490615593530405056055952622249066180336803996949444124622212096805545953751253607916170340397933039";
//公钥
private static final String PUB_KEY = "65537";
//私钥
private static final String PRI_KEY = "26900155715313643087786516528374548998821559381075740707715132776187148793016466508650068087107695523642202737697714709374658856733792614490943874205956727606674634563665154616758939576547663715234643273055658829482813503959459653708062875625210008961239643775661357655599312857249418610810177817213648575161";

@Bind(R.id.encode_et)
EditText encodeEt;
@Bind(R.id.decode_et)
EditText decodeEt;
@Bind(R.id.result)
TextView result;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.rsa_layout, null);
ButterKnife.bind(this, view);
return view;
}

@OnClick(R.id.encode)
public void encode() {
String srcStr = encodeEt.getText().toString();
try {
//获取一个公钥/私钥生成工厂
KeyFactory keyFactory = KeyFactory.getInstance("rsa");
//1.大素数的乘积
//2.公钥
RSAPublicKeySpec rsaPublicKey = new RSAPublicKeySpec(new BigInteger(MODULUS), new BigInteger(PUB_KEY));
//生成公钥
PublicKey publicKey = keyFactory.generatePublic(rsaPublicKey);
//获取一个密码生成器
Cipher cipher = Cipher.getInstance("rsa");
//初始化密码生成器
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
//加密
byte[] bytes = cipher.doFinal(srcStr.getBytes("UTF-8"));
String s = Base64.encodeToString(bytes, Base64.DEFAULT);
decodeEt.setText(s);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (InvalidKeySpecException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
}
}

@OnClick(R.id.decode)
public void decode() {
try {
KeyFactory keyFactory = KeyFactory.getInstance("rsa");
RSAPrivateKeySpec rsaPrivateKeySpec = new RSAPrivateKeySpec(new BigInteger(MODULUS), new BigInteger(PRI_KEY));
PrivateKey privateKey = keyFactory.generatePrivate(rsaPrivateKeySpec);
Cipher cipher = Cipher.getInstance("rsa");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
byte[] bytes = cipher.doFinal(Base64.decode(decodeEt.getText().toString(), Base64.DEFAULT));
String s = new String(bytes, 0, bytes.length);
result.setText(s);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (InvalidKeySpecException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
}
}
}