How to implement data encryption and decryption in Java

How to implement data encryption and decryption in Java, specific code examples are required

Abstract:
Data encryption and decryption play a vital role in the field of information security important role. This article will introduce how to use the Java programming language to implement data encryption and decryption, and provide specific code examples. These include the use of symmetric encryption algorithms and asymmetric encryption algorithms.

1. Symmetric encryption algorithm
Symmetric encryption algorithm uses the same key to encrypt and decrypt data. Commonly used symmetric encryption algorithms in Java include DES, 3DES and AES. The following is a sample code that uses the AES algorithm for data encryption and decryption:

1. Import related Java class libraries and packages
   import javax.crypto.Cipher;
   import javax.crypto. SecretKey;
   import javax.crypto.SecretKeyFactory;
   import javax.crypto.spec.DESKeySpec;

2. Define encryption and decryption methods
   public class SymmetricEncryption {
   private static final String ALGORITHM = "AES";

   public static byte[] encrypt(byte[] plaintext, byte[] key) throws Exception {

    SecretKey secretKey = SecretKeyFactory.getInstance(ALGORITHM).generateSecret(new DESKeySpec(key));
    Cipher cipher = Cipher.getInstance(ALGORITHM);
    cipher.init(Cipher.ENCRYPT_MODE, secretKey);
    return cipher.doFinal(plaintext);

   }

   public static byte[] decrypt(byte[] ciphertext, byte[] key) throws Exception {

    SecretKey secretKey = SecretKeyFactory.getInstance(ALGORITHM).generateSecret(new DESKeySpec(key));
    Cipher cipher = Cipher.getInstance(ALGORITHM);
    cipher.init(Cipher.DECRYPT_MODE, secretKey);
    return cipher.doFinal(ciphertext);

   }
   }

3. Use encryption and decryption methods
   public class Main {
   public static void main(String[] args) throws Exception {

    byte[] key = "secretkey".getBytes(); // 密钥
    byte[] plaintext = "Hello, world!".getBytes(); // 明文
   
    byte[] ciphertext = SymmetricEncryption.encrypt(plaintext, key); // 加密
    System.out.println("Ciphertext: " + new String(ciphertext));
   
    byte[] decryptedText = SymmetricEncryption.decrypt(ciphertext, key); // 解密
    System.out.println("Decrypted Text: " + new String(decryptedText));

   }
   }

2. Asymmetric encryption algorithm
Asymmetric encryption algorithms use different keys to encrypt and decrypt data. Commonly used asymmetric encryption algorithms in Java include RSA. The following is a sample code that uses the RSA algorithm for data encryption and decryption:

1. Import related Java class libraries and packages
   import java.security.KeyPair;
   import java.security. KeyPairGenerator;
   import java.security.PrivateKey;
   import java.security.PublicKey;
   import javax.crypto.Cipher;

2. Define encryption and decryption methods
   public class AsymmetricEncryption {
   private static final String ALGORITHM = "RSA";

   public static byte[] encrypt(byte[] plaintext, PublicKey publicKey) throws Exception {

    Cipher cipher = Cipher.getInstance(ALGORITHM);
    cipher.init(Cipher.ENCRYPT_MODE, publicKey);
    return cipher.doFinal(plaintext);

   }

   public static byte[] decrypt(byte[] ciphertext, PrivateKey privateKey) throws Exception {

    Cipher cipher = Cipher.getInstance(ALGORITHM);
    cipher.init(Cipher.DECRYPT_MODE, privateKey);
    return cipher.doFinal(ciphertext);

   }
   }

3. Use encryption and decryption Method
   public class Main {
   public static void main(String[] args) throws Exception {

    KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);
    KeyPair keyPair = keyPairGenerator.generateKeyPair();
    PublicKey publicKey = keyPair.getPublic();
    PrivateKey privateKey = keyPair.getPrivate();
   
    byte[] plaintext = "Hello, world!".getBytes(); // 明文
   
    byte[] ciphertext = AsymmetricEncryption.encrypt(plaintext, publicKey); // 加密
    System.out.println("Ciphertext: " + new String(ciphertext));
   
    byte[] decryptedText = AsymmetricEncryption.decrypt(ciphertext, privateKey); // 解密
    System.out.println("Decrypted Text: " + new String(decryptedText));

   }
   }

Conclusion:
To implement data encryption and decryption in Java, you can use symmetric encryption algorithms and asymmetric encryption algorithms. This article gives specific code examples for data encryption and decryption using AES and RSA algorithms. Readers can choose a suitable encryption algorithm based on actual needs and implement it according to the code in the example. At the same time, in order to improve data security, it is recommended to add a key generation and management mechanism to practical applications to avoid key leakage.

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