Java 如何在android studio中对不同活动的文本进行加密/解密

我试着在android studio中开发一个文本加密/解密应用程序。因此，在MainActivity.java上，我运行了一个加密和解密的示例代码

MainActivity.java

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class MainActivity extends AppCompatActivity {

Button btn,btn2;
static final String TAG = "SymmetricAlgorithmAES";
String secr="k";
String secr2="d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr+secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");

    // Original text
    String theTestText = "This is just a simple test";
    TextView tvorig = (TextView)findViewById(R.id.tvorig);
    tvorig.setText("\n[ORIGINAL]:\n" + theTestText + "\n");

    // Encode the original data with AES
    byte[] encodedBytes = null;
    try {
        Cipher c = Cipher.getInstance("AES");
        c.init(Cipher.ENCRYPT_MODE, sks);
        encodedBytes = c.doFinal(theTestText.getBytes());
    } catch (Exception e) {
        Log.e(TAG, "AES encryption error");
    }
    TextView tvencoded = (TextView)findViewById(R.id.tvencoded);
    tvencoded.setText("" +
            Base64.encodeToString(encodedBytes, Base64.DEFAULT) + "\n");

    // Decode the encoded data with AES
    byte[] decodedBytes = null;
    try {
        Cipher c = Cipher.getInstance("AES");
        c.init(Cipher.DECRYPT_MODE, sks);
        decodedBytes = c.doFinal(encodedBytes);
    } catch (Exception e) {
        Log.e(TAG, "AES decryption error");
    }
    TextView tvdecoded = (TextView)findViewById(R.id.tvdecoded);
    tvdecoded.setText("[DECODED]:\n" + new String(decodedBytes) + "\n");

   }

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class Encryption extends AppCompatActivity {

static final String TAG = "SymmetricAlgorithmAES";
String secr="k";
String secr2="d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.encryption);
    enc_text_edt=(EditText)findViewById(R.id.enc_text_edt);
    enc_text_btn=(Button)findViewById(R.id.enc_text_btn);
    enctv=(TextView)findViewById(R.id.enctv);

    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr+secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");

    final SecretKeySpec finalSks = sks;
    enc_text_btn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            try {

                // Encode the original data with AES
                byte[] encodedBytes = null;
                try {
                    Cipher c = Cipher.getInstance("AES");
                    c.init(Cipher.ENCRYPT_MODE, finalSks);
                    encodedBytes = c.doFinal(enc_text_edt.getText().toString().getBytes());
                } catch (Exception e) {
                    Log.e(TAG, "AES encryption error");
                }


                enctv.setText("[ENCRYPTED]:\n" +
                        Base64.encodeToString(encodedBytes, Base64.DEFAULT) + "\n");


                enc_text_edt.setText("");


            } catch (Exception e) {

                e.printStackTrace();
            }

        }
    });
}
}

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class Decryption extends AppCompatActivity {

Button dec_text_btn;
TextView dec_edtext_view, dectv;

static final String TAG = "SymmetricAlgorithmAES";
String secr = "k";
String secr2 = "d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.decryption);
    dec_text_btn = (Button) findViewById(R.id.dec_text_btn);
    dec_edtext_view = (EditText) findViewById(R.id.dec_edtext_view);
    dectv = (TextView) findViewById(R.id.dectv);


    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr + secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");


    final SecretKeySpec finalSks = sks;
    dec_text_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            try {

                // Decode the encoded data with AES

                byte[] decodedBytes = null;
                try {
                    Cipher c = Cipher.getInstance("AES");
                    c.init(Cipher.DECRYPT_MODE, finalSks);
                    decodedBytes= c.doFinal(dec_edtext_view.getText().toString().getBytes());
                    } catch (Exception e) {
                        Log.e(TAG, "AES encryption error");
                    }

                    dectv.setText("[DECRYPTED]:\n" + new String(decodedBytes) + "\n");


                } catch (Exception e) {
                    e.printStackTrace();
                    Toast.makeText(getApplicationContext(), "creptography exception see log cat....", Toast.LENGTH_SHORT).show();
                }
        }
    });
}
}

以上代码工作正常，输出正确。但当我试图修改代码并尝试在不同的活动中编写加密和解密时，解密部分无法正常工作

以下是加密部分的代码，该部分工作正常，没有任何错误

Encryption.java

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class MainActivity extends AppCompatActivity {

Button btn,btn2;
static final String TAG = "SymmetricAlgorithmAES";
String secr="k";
String secr2="d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr+secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");

    // Original text
    String theTestText = "This is just a simple test";
    TextView tvorig = (TextView)findViewById(R.id.tvorig);
    tvorig.setText("\n[ORIGINAL]:\n" + theTestText + "\n");

    // Encode the original data with AES
    byte[] encodedBytes = null;
    try {
        Cipher c = Cipher.getInstance("AES");
        c.init(Cipher.ENCRYPT_MODE, sks);
        encodedBytes = c.doFinal(theTestText.getBytes());
    } catch (Exception e) {
        Log.e(TAG, "AES encryption error");
    }
    TextView tvencoded = (TextView)findViewById(R.id.tvencoded);
    tvencoded.setText("" +
            Base64.encodeToString(encodedBytes, Base64.DEFAULT) + "\n");

    // Decode the encoded data with AES
    byte[] decodedBytes = null;
    try {
        Cipher c = Cipher.getInstance("AES");
        c.init(Cipher.DECRYPT_MODE, sks);
        decodedBytes = c.doFinal(encodedBytes);
    } catch (Exception e) {
        Log.e(TAG, "AES decryption error");
    }
    TextView tvdecoded = (TextView)findViewById(R.id.tvdecoded);
    tvdecoded.setText("[DECODED]:\n" + new String(decodedBytes) + "\n");

   }

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class Encryption extends AppCompatActivity {

static final String TAG = "SymmetricAlgorithmAES";
String secr="k";
String secr2="d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.encryption);
    enc_text_edt=(EditText)findViewById(R.id.enc_text_edt);
    enc_text_btn=(Button)findViewById(R.id.enc_text_btn);
    enctv=(TextView)findViewById(R.id.enctv);

    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr+secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");

    final SecretKeySpec finalSks = sks;
    enc_text_btn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            try {

                // Encode the original data with AES
                byte[] encodedBytes = null;
                try {
                    Cipher c = Cipher.getInstance("AES");
                    c.init(Cipher.ENCRYPT_MODE, finalSks);
                    encodedBytes = c.doFinal(enc_text_edt.getText().toString().getBytes());
                } catch (Exception e) {
                    Log.e(TAG, "AES encryption error");
                }


                enctv.setText("[ENCRYPTED]:\n" +
                        Base64.encodeToString(encodedBytes, Base64.DEFAULT) + "\n");


                enc_text_edt.setText("");


            } catch (Exception e) {

                e.printStackTrace();
            }

        }
    });
}
}

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class Decryption extends AppCompatActivity {

Button dec_text_btn;
TextView dec_edtext_view, dectv;

static final String TAG = "SymmetricAlgorithmAES";
String secr = "k";
String secr2 = "d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.decryption);
    dec_text_btn = (Button) findViewById(R.id.dec_text_btn);
    dec_edtext_view = (EditText) findViewById(R.id.dec_edtext_view);
    dectv = (TextView) findViewById(R.id.dectv);


    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr + secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");


    final SecretKeySpec finalSks = sks;
    dec_text_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            try {

                // Decode the encoded data with AES

                byte[] decodedBytes = null;
                try {
                    Cipher c = Cipher.getInstance("AES");
                    c.init(Cipher.DECRYPT_MODE, finalSks);
                    decodedBytes= c.doFinal(dec_edtext_view.getText().toString().getBytes());
                    } catch (Exception e) {
                        Log.e(TAG, "AES encryption error");
                    }

                    dectv.setText("[DECRYPTED]:\n" + new String(decodedBytes) + "\n");


                } catch (Exception e) {
                    e.printStackTrace();
                    Toast.makeText(getApplicationContext(), "creptography exception see log cat....", Toast.LENGTH_SHORT).show();
                }
        }
    });
}
}

解密代码

解密.java

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class MainActivity extends AppCompatActivity {

Button btn,btn2;
static final String TAG = "SymmetricAlgorithmAES";
String secr="k";
String secr2="d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr+secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");

    // Original text
    String theTestText = "This is just a simple test";
    TextView tvorig = (TextView)findViewById(R.id.tvorig);
    tvorig.setText("\n[ORIGINAL]:\n" + theTestText + "\n");

    // Encode the original data with AES
    byte[] encodedBytes = null;
    try {
        Cipher c = Cipher.getInstance("AES");
        c.init(Cipher.ENCRYPT_MODE, sks);
        encodedBytes = c.doFinal(theTestText.getBytes());
    } catch (Exception e) {
        Log.e(TAG, "AES encryption error");
    }
    TextView tvencoded = (TextView)findViewById(R.id.tvencoded);
    tvencoded.setText("" +
            Base64.encodeToString(encodedBytes, Base64.DEFAULT) + "\n");

    // Decode the encoded data with AES
    byte[] decodedBytes = null;
    try {
        Cipher c = Cipher.getInstance("AES");
        c.init(Cipher.DECRYPT_MODE, sks);
        decodedBytes = c.doFinal(encodedBytes);
    } catch (Exception e) {
        Log.e(TAG, "AES decryption error");
    }
    TextView tvdecoded = (TextView)findViewById(R.id.tvdecoded);
    tvdecoded.setText("[DECODED]:\n" + new String(decodedBytes) + "\n");

   }

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class Encryption extends AppCompatActivity {

static final String TAG = "SymmetricAlgorithmAES";
String secr="k";
String secr2="d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.encryption);
    enc_text_edt=(EditText)findViewById(R.id.enc_text_edt);
    enc_text_btn=(Button)findViewById(R.id.enc_text_btn);
    enctv=(TextView)findViewById(R.id.enctv);

    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr+secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");

    final SecretKeySpec finalSks = sks;
    enc_text_btn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            try {

                // Encode the original data with AES
                byte[] encodedBytes = null;
                try {
                    Cipher c = Cipher.getInstance("AES");
                    c.init(Cipher.ENCRYPT_MODE, finalSks);
                    encodedBytes = c.doFinal(enc_text_edt.getText().toString().getBytes());
                } catch (Exception e) {
                    Log.e(TAG, "AES encryption error");
                }


                enctv.setText("[ENCRYPTED]:\n" +
                        Base64.encodeToString(encodedBytes, Base64.DEFAULT) + "\n");


                enc_text_edt.setText("");


            } catch (Exception e) {

                e.printStackTrace();
            }

        }
    });
}
}

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class Decryption extends AppCompatActivity {

Button dec_text_btn;
TextView dec_edtext_view, dectv;

static final String TAG = "SymmetricAlgorithmAES";
String secr = "k";
String secr2 = "d";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.decryption);
    dec_text_btn = (Button) findViewById(R.id.dec_text_btn);
    dec_edtext_view = (EditText) findViewById(R.id.dec_edtext_view);
    dectv = (TextView) findViewById(R.id.dectv);


    //code to use my specified defined key
    byte[] key = new byte[0];
    try {
        key = (secr + secr2).getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
    MessageDigest sha = null;
    try {
        sha = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    key = sha.digest(key);
    key = Arrays.copyOf(key, 16); // use only first 128 bit

    SecretKeySpec sks = new SecretKeySpec(key, "AES");


    final SecretKeySpec finalSks = sks;
    dec_text_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            try {

                // Decode the encoded data with AES

                byte[] decodedBytes = null;
                try {
                    Cipher c = Cipher.getInstance("AES");
                    c.init(Cipher.DECRYPT_MODE, finalSks);
                    decodedBytes= c.doFinal(dec_edtext_view.getText().toString().getBytes());
                    } catch (Exception e) {
                        Log.e(TAG, "AES encryption error");
                    }

                    dectv.setText("[DECRYPTED]:\n" + new String(decodedBytes) + "\n");


                } catch (Exception e) {
                    e.printStackTrace();
                    Toast.makeText(getApplicationContext(), "creptography exception see log cat....", Toast.LENGTH_SHORT).show();
                }
        }
    });
}
}

---

请帮我纠正这个错误。在执行解密部分时，它直接显示异常“加密异常请参阅日志cat”

在阅读您的代码后，我认为我发现了问题，您编码到Base64，但从未解码。在

加密中

执行以下操作

enctv.setText（“[加密]：\n”+
Base64.encodeToString（encodedBytes，Base64.DEFAULT）+“\n”）；

我猜用户会将其复制到解密字段，但在他们单击按钮后，您会这样做

decodedBytes=c.doFinal（dec_edtext_view.getText（）.toString（）.getBytes（））；

而不是从Base64解码。 我还想补充几点： 你的安全是不安全的，你几乎没有实现任何安全层时，钥匙在飞机上的网站像这样

注1：

密钥应随机生成，并使用。 您可以通过执行以下操作轻松完成此操作：

byte[]key=新字节[16]；
新SecureRandom（）.nextBytes（密钥）；

注2：

如果用户键入了相同的消息，请使用此选项。例如，考虑下面的加密“Hello World”的场景，并将其显示为“ABCFDGHIJK”。现在你再次发送它，它又是“ABCDEFGHIJK”。 对于IV，每次都会不同，只要您为每条消息生成一个新的IV，您就应该将此IV附加到消息中，以便稍后在解密时可以提取它

注3：

在声明

密码时

使用的次数超过

AES

。 有一篇关于如何提高您的安全性和知识的精彩文章：

注4：

如果发生异常，请不要像什么都没发生一样继续，您应该正确处理它，而不要继续使用依赖于异常原因的代码

注5：

---

更深入地学习Java，而不是跳到密码学，您的字段应该是私有的，如果您计划稍后使用它，如果您确实检查它是否为null，那么最后不要声明null。不要在get字节中声明“UTF-8”，用一个常量声明a，比如“UTF-8”，这很容易用

字符集来完成。forName（“UTF-8”）

我同意所说的一切

此外，您可能应该从活动中获得所有这些内容，并将其放入助手类中。这样，它将可重用，并且您可以使用如下所示的内容测试它的输入和输出（无需复制和粘贴）：

    public void myEncryptionTest(){
    String message = "This is the message to encrypt and decrypt.";
    String pass = "pass";
    String encryption = Crypto.myEncrypt(message.getBytes(), pass);
    byte[] decryption = Crypto.myDecrypt(encryption, pass);
    String decrypted = new String(decryption);
    Log.d("****DECRYPTION:  ", decrypted);
}

---

助手类被称为“Crypto”，您正在测试的两个静态函数是“myEncrypt”和“myDecrypt”。

logcat包含什么？另外，请检查嵌套的try-catch中是否存在任何异常，并共享它