Examples of AES encryption and decryption using Hutool in Java

Preface

In the field of information security, data encryption is one of the important means to protect data confidentiality, integrity and availability. As a symmetric encryption algorithm that is currently widely used, AES (Advanced Encryption Standard) plays an important role in various application systems due to its efficient and secure characteristics. As a programming language widely used in enterprise-level development, Java's powerful encryption library provides developers with rich encryption and decryption tools. However, when using Java's encryption API directly for AES encryption and decryption, you may face problems such as cumbersome code and difficult understanding. At this time, Hutool, a Java tool library, appears particularly practical.

Hutool is a small and complete Java tool library that simplifies common tedious operations in Java development, including but not limited to date processing, file operations, encryption and decryption. In terms of encryption and decryption, Hutool provides a simple and easy-to-use API, making AES encryption and decryption easy. This article will introduce in detail how to use Hutool for AES encryption and decryption in Java projects.

1. Introduction and introduction of Hutool

1.1 Introduction to Hutool

Hutool is a small and complete Java tool library. It uses static method encapsulation to reduce the learning cost of related APIs, improve work efficiency, and make Java have the simplicity of functional programming. The tools and methods in Hutool come from each user's meticulous work. They cover all aspects of the underlying code of Java development. They are not only a powerful tool for solving small problems in large-scale project development, but also an efficiency responsibility in small projects.

1.2 Introducing Hutool

In Maven project, Hutool can be introduced by adding the following dependencies:

&lt;dependency&gt;  
    &lt;groupId&gt;&lt;/groupId&gt;  
    &lt;artifactId&gt;hutool-all&lt;/artifactId&gt;  
    &lt;version&gt;Your version number&lt;/version&gt;  
&lt;/dependency&gt;

Please replace your version number with the current latest Hutool version number to ensure the latest features and fixes are used.

2. Basics of AES encryption and decryption

AES encryption is a symmetric encryption algorithm, i.e. encryption and decryption use the same key. AES supports three lengths of keys: 128-bit, 192-bit and 256-bit. During the AES encryption process, the data is first divided into multiple fixed-length blocks, and then each block is encrypted independently.

The AES encryption process can be roughly divided into the following steps:

Key Expansion: Extend the user-provided key into a series of round keys.
Initial Round: Perform specific operations on the plaintext block with the initial wheel key (such as XOR, replacement, etc.).
Intermediate Rounds: Multiple iterations of the results of the initial round are encrypted, each iteration using a different round key.
Final Round: Similar to the middle wheel, but may contain some additional operations such as column confusion, etc.
Output: The result of the final round is the encrypted ciphertext.

The decryption process is the inverse operation of the encryption process, which uses the same key and algorithm to restore the ciphertext to plaintext.

3. Use Hutool for AES encryption and decryption

3.1 Encryption

In Hutool, AES encryption mainly depends onSecureUtilClass andAESkind. Here is a simple AES encryption example:

import ;  
import ;  
  
public class AesEncryptExample {  
    public static void main(String[] args) {  
        // Raw data        String content = "Hello Hutool AES!";  
        // Key, AES requires the key length to be 128/192/256 bits        byte[] keyBytes = (256).getEncoded();  
          
        // Create AES encrypted object, use ECB/PKCS5Padding        AES aes = (keyBytes, "ECB/PKCS5Padding");  
          
        // Encryption        byte[] encrypt = (content);  
          
        // Encryption results are usually used for storage or transmission, and here they are simply printed in Base64 encoding form        String encryptHex = (content);  
        ("Encryption results (Hex): " + encryptHex);  
          
        // If you need a raw byte array, use the encrypt method        // (().encodeToString(encrypt));  
    }  
}

Note: In practical applications, the keykeyBytesIt should be generated and stored safely, avoiding hard-coded in the code.

3.2 Decryption

The decryption process is similar to the encryption process, except that the encrypted data (ciphertext) is used as input and the AES decryption object is restored to the original data (plaintext).

// Assume encryptHex is the Hex string obtained by previous encryptionString encryptHex = "..."; // This should be the encrypted Hex string  
// Decrypt with the same key and algorithmAES aes = (keyBytes, "ECB/PKCS5Padding");  
String decryptStr = (encryptHex);  
  
("Decryption result: " + decryptStr);

4. AES encryption mode and fill mode

The AES encryption algorithm supports multiple modes and fill methods. Different modes and fill methods will affect the results of encryption and decryption. In Hutool, AES encrypted and decrypted objects can be created by specifying modes (such as ECB, CBC, etc.) and filling methods (such as PKCS5Padding, NoPadding, etc.).

Mode (Mode): Determines how the key is used during the encryption process. Common patterns include ECB, CBC, CFB, OFB, etc.
Padding method: Since AES encryption requires that the length of the input data must be an integer multiple of the block size (AES block size is 128 bits), when the input data length does not meet the requirements, the requirements need to be met through fill. Common filling methods include PKCS5Padding, PKCS7Padding, NoPadding, etc.

When selecting modes and fill methods, it needs to be decided based on the specific application scenario and security needs. For example, although the ECB mode is simple to implement, it has low security and is not suitable for scenarios where high security is required; while the CBC mode improves security by introducing initialization vectors (IVs), which is one of the more commonly used modes.

5. Safety and performance considerations

Security and performance are two important considerations when using AES encryption and decryption.

Security: Ensure the secure generation, storage and transmission of keys is the key to ensuring encryption security. In addition, choosing the right encryption mode and filling method is also an important means to improve security.
performance: Although AES encryption and decryption are efficient, they may still have an impact on performance when processing large amounts of data. Therefore, in performance-sensitive applications, it is necessary to reasonably design encryption and decryption strategies, such as using asynchronous processing, batch encryption and decryption to improve performance.

6. Summary

As a practical Java tool library, Hutool provides developers with a simple and easy-to-use AES encryption and decryption API. Through this article, readers can learn how to use Hutool for AES encryption and decryption in Java projects, including the basic steps of encryption and decryption, the choice of AES encryption mode and fill mode, and security and performance considerations. I hope this article will be helpful to readers' learning and practice in Java encryption and decryption.

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