Java is one of the most widely used programming languages ??at present. It has the advantages of cross-platform, safety, reliability, and easy maintenance. However, because Java applications widely exist on the Internet, they have become one of the main targets of cyber attacks. Therefore, when developing Java programs, you must pay attention to safe programming practices to ensure the safety and reliability of the program.

This article will discuss Java core security programming practices, including security programming basics, cryptography, defensive programming, code auditing, etc., and provide specific code examples.

1. Basics of secure programming

1. Input validation

Input validation is an important concept in Java secure programming, that is, before receiving user input data , verify and filter the data. This helps prevent attacks such as SQL injection, cross-site scripting (XSS), and cross-site request forgery (CSRF). Methods to implement input validation can include regular expressions, specialized input validation libraries, etc.

Code example:

// 對手機(jī)號進(jìn)行驗(yàn)證
Pattern pattern = Pattern.compile("^1[3|4|5|7|8]\d{9}$");
Matcher matcher = pattern.matcher(phoneNumber);
if(matcher.matches()){
    // 如果驗(yàn)證通過，執(zhí)行相應(yīng)操作
}else{
    // 如果驗(yàn)證不通過，拋出異?；蜻M(jìn)行其他錯(cuò)誤處理
}

2. Permission management

Permission management can control who can access which resources in the program. In Java, you can use frameworks to implement permission management, such as Spring Security, etc.

Code Example:

// 在Controller中使用Spring Security進(jìn)行權(quán)限管理
@PreAuthorize("hasRole('admin')")
@RequestMapping(value = "/delete/{id}", method = RequestMethod.DELETE)
public void delete(@PathVariable Integer id) {
    // 執(zhí)行刪除操作
}

3. Security Headers

HTTP headers can contain information about the browser, server, and connection. By setting the correct security headers, you can prevent some attacks such as clickjacking, CORS attacks, etc. Commonly used security headers include X-Frame-Options, X-XSS-Protection, Content-Security-Policy, etc.

Code example:

// 在Spring中設(shè)置安全標(biāo)頭
@Configuration
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.headers()
            .frameOptions().sameOrigin()
            .xssProtection().block(false)
            .contentSecurityPolicy("default-src 'self'");
    }
}

2. Cryptography

Cryptography is an important field in protecting information security, including encryption, hashing and digital signature technologies. In Java, commonly used cryptography implementations include BouncyCastle and Java Cryptography Extension (JCE).

1. Encryption

Encryption is the process of converting plain text into cipher text to protect data from access by unauthorized parties. In Java, commonly used encryption algorithms include AES, DES, RSA, etc.

Code example:

// 使用AES加密數(shù)據(jù)
SecretKey secret = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret);
byte[] encryptedBytes = cipher.doFinal(plainText.getBytes("UTF-8"));

2. Hash

Hashing is the process of irreversibly transforming data of any size. In Java, commonly used hashing algorithms include MD5, SHA-1, SHA-256, etc.

Code example:

// 使用SHA-256哈希數(shù)據(jù)
MessageDigest md = MessageDigest.getInstance("SHA-256");
md.update(data.getBytes("UTF-8"));
byte[] hashBytes = md.digest();

3. Digital signature

Digital signature is to use a private key to encrypt information to ensure the integrity and authentication of the information . In Java, commonly used digital signature algorithms include RSA and DSA.

Code example:

// 使用RSA對數(shù)據(jù)進(jìn)行數(shù)字簽名
PrivateKey privateKey = getPrivateKey();
Signature signature = Signature.getInstance("SHA256withRSA");
signature.initSign(privateKey);
signature.update(data.getBytes("UTF-8"));
byte[] signatureBytes = signature.sign();

3. Defensive programming

Defensive programming is a programming method that considers possible attacks when writing code to prevent security loopholes. Commonly used defensive programming methods in Java include parameter checking, exception handling, and logging.

1. Parameter checking

Before performing any operation, the entered parameters should be verified and checked. Checking parameters can prevent some security holes, such as null pointer exceptions, out-of-bounds access, etc.

Code sample:

// 對方法參數(shù)進(jìn)行檢查
public void operation(String data) {
    if (data == null || data.isEmpty()) {
        throw new IllegalArgumentException("data不能為空");
    }
    // 執(zhí)行相應(yīng)操作
}

2. Exception handling

When handling exceptions, the exception information should be recorded in the log for better processing Debugging and troubleshooting. At the same time, when returning abnormal information to the outside world, you should avoid returning sensitive information.

Code sample:

// 在異常處理中記錄日志并返回友好的錯(cuò)誤信息
try {
    // 執(zhí)行相應(yīng)操作
} catch (Exception e) {
    logger.error("操作失敗", e);
    throw new RuntimeException("操作失敗，請稍后再試");
}

3. Logging

Logging in the program can help developers better understand the operation of the program and have Helps identify and fix security vulnerabilities. When logging, you should avoid writing sensitive information such as passwords, credit card numbers, etc.

Code sample:

// 記錄日志
logger.info("用戶{}嘗試登錄，結(jié)果為{}", username, result);

4. Code audit

Code audit is a way to check for potential security vulnerabilities in applications. When conducting Java code audits, you should focus on input validation, SQL injection, XSS attacks, file inclusion, permission management, etc.

1. Input verification

Input verification is the most important part when conducting Java code auditing. When checking input validation, you should pay attention to all user input, including GET, POST requests, cookies, etc.

2. SQL injection

SQL injection is a common attack technique, which also needs special attention in Java code auditing. SQL queries, SQL updates, stored procedures, etc. should be checked for SQL injection vulnerabilities.

3. XSS Attack

XSS attack is a method of attacking users by injecting malicious scripts into web applications. In Java code auditing, all user input should be checked and verified for malicious scripts.

4. File inclusion

File inclusion refers to referencing a file to view or execute the contents of an unexpected file, thereby attacking the system. In Java code auditing, all file inclusion points in the code system should be checked, especially file inclusions that use user-entered paths.

5. Permission management

In Java code audit, all permission management should be checked, especially all code that may contain user input data. Check for user input that has not been handled correctly, such as arbitrary file upload vulnerabilities, etc.

To sum up, Java core security programming practices need to involve security programming basics, cryptography, defensive programming, code auditing, etc. The above provides some specific programming practices and code examples, noting that secure programming is always risky and requires constant adaptation to new security threats and vulnerabilities. Therefore, when writing Java code, you need to always pay attention to safe programming practices to ensure the safety and reliability of your program.

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