How to use Java backend technology to implement data encryption and decryption?

How to use Java back-end technology to implement data encryption and decryption?

Overview:
In modern Internet application development, data security is paid more and more attention. One important aspect is the encryption and decryption of data. This article will introduce how to use Java back-end technology to implement data encryption and decryption operations, and provide corresponding code examples.

1. Symmetric encryption algorithm
Symmetric encryption algorithm uses the same key for encryption and decryption operations, and is characterized by fast speed. Commonly used symmetric encryption algorithms include DES, 3DES, AES, etc.

The following is a sample code that uses the AES algorithm to implement symmetric encryption and decryption:

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class SymmetricEncryptionExample {
    public static String encrypt(String plainText, String key) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] encryptedBytes = cipher.doFinal(plainText.getBytes());
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }

    public static String decrypt(String encryptedText, String key) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        byte[] encryptedBytes = Base64.getDecoder().decode(encryptedText);
        byte[] decryptedBytes = cipher.doFinal(encryptedBytes);
        return new String(decryptedBytes);
    }

    public static void main(String[] args) {
        try {
            String plainText = "Hello, encryption!";
            String key = "Thisisa128bitKey";
            String encryptedText = encrypt(plainText, key);
            System.out.println("Encrypted text: " + encryptedText);
            String decryptedText = decrypt(encryptedText, key);
            System.out.println("Decrypted text: " + decryptedText);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

In the above example, we use the AES algorithm to encrypt and decrypt plaintext. It should be noted that the key length needs to meet the requirements of the corresponding algorithm.

2. Asymmetric encryption algorithm
The asymmetric encryption algorithm uses two keys, one for encryption and the other for decryption. Commonly used asymmetric encryption algorithms include RSA, DSA, etc.

The following is a sample code that uses the RSA algorithm to implement asymmetric encryption and decryption:

import javax.crypto.Cipher;
import java.security.*;

public class AsymmetricEncryptionExample {
    public static byte[] encrypt(byte[] plainText, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(plainText);
    }

    public static byte[] decrypt(byte[] encryptedText, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(encryptedText);
    }

    public static void main(String[] args) {
        try {
            String plainText = "Hello, encryption!";
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            PublicKey publicKey = keyPair.getPublic();
            PrivateKey privateKey = keyPair.getPrivate();
            byte[] encryptedText = encrypt(plainText.getBytes(), publicKey);
            System.out.println("Encrypted text: " + new String(encryptedText));
            byte[] decryptedText = decrypt(encryptedText, privateKey);
            System.out.println("Decrypted text: " + new String(decryptedText));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

In the above example, we use the RSA algorithm to encrypt and decrypt plaintext. First, you need to generate a pair of public and private keys, then use the public key for encryption and the private key for decryption.

3. Summary
This article introduces how to use Java back-end technology to implement data encryption and decryption operations. Through the sample code of symmetric encryption algorithm and asymmetric encryption algorithm, we can learn how to operate using Java's built-in encryption library. In actual application development, appropriate encryption algorithms can be selected according to specific needs, and key management can be performed according to security requirements.

It should be noted that although the encryption algorithm can provide a certain degree of security, it cannot absolutely guarantee the security of the data. In practical applications, other security measures need to be paid attention to, such as access control, firewalls, etc.

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