iOS開發基礎109-網路安全

Mr.陳發表於2024-07-17

在iOS開發中,保障應用的網路安全是一個非常重要的環節。以下是一些常見的網路安全措施及對應的示例程式碼:

Swift版

1. 使用HTTPS

確保所有的網路請求使用HTTPS協議,以加密資料傳輸,防止中間人攻擊。

示例程式碼:

在Info.plist中配置App Transport Security (ATS):

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <false/>
</dict>

2. SSL Pinning

透過SSL Pinning可以確保應用程式只信任指定的伺服器證書,防止被劫持到偽造的伺服器。

示例程式碼:

import Foundation

class URLSessionPinningDelegate: NSObject, URLSessionDelegate {
  func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
        if let serverTrust = challenge.protectionSpace.serverTrust,
           SecTrustEvaluate(serverTrust, nil) == errSecSuccess,
           let serverCertificate = SecTrustGetCertificateAtIndex(serverTrust, 0) {

            let localCertificateData = try? Data(contentsOf: Bundle.main.url(forResource: "your_cert", withExtension: "cer")!)
            let serverCertificateData = SecCertificateCopyData(serverCertificate) as Data

            if localCertificateData == serverCertificateData {
                let credential = URLCredential(trust: serverTrust)
                completionHandler(.useCredential, credential)
                return
            }
        }
        completionHandler(.cancelAuthenticationChallenge, nil)
  }
}

// Usage
let url = URL(string: "https://yoursecurewebsite.com")!
let session = URLSession(configuration: .default, delegate: URLSessionPinningDelegate(), delegateQueue: nil)
let task = session.dataTask(with: url) { data, response, error in
    // Handle response
}
task.resume()

3. 防止SQL隱碼攻擊

在處理使用者輸入時,使用引數化查詢來防止SQL隱碼攻擊。

示例程式碼:

import SQLite3

func queryDatabase(userInput: String) {
    var db: OpaquePointer?
    // Open database (assuming dbPath is the path to your database)
    sqlite3_open(dbPath, &db)

    var queryStatement: OpaquePointer?
    let query = "SELECT * FROM users WHERE username = ?"
    
    if sqlite3_prepare_v2(db, query, -1, &queryStatement, nil) == SQLITE_OK {
        sqlite3_bind_text(queryStatement, 1, userInput, -1, nil)
        
        while sqlite3_step(queryStatement) == SQLITE_ROW {
            // Process results
        }
    }
    
    sqlite3_finalize(queryStatement)
    sqlite3_close(db)
}

4. Data Encryption

在儲存敏感資料時,使用iOS的加密庫來加密資料,比如使用Keychain

示例程式碼:

import Security

func saveToKeychain(key: String, data: Data) -> OSStatus {
    let query: [String: Any] = [
        kSecClass as String: kSecClassGenericPassword,
        kSecAttrAccount as String: key,
        kSecValueData as String: data
    ]

    SecItemDelete(query as CFDictionary) // Delete any existing item
    return SecItemAdd(query as CFDictionary, nil) // Add new item
}

func loadFromKeychain(key: String) -> Data? {
    let query: [String: Any] = [
        kSecClass as String: kSecClassGenericPassword,
        kSecAttrAccount as String: key,
        kSecReturnData as String: kCFBooleanTrue!,
        kSecMatchLimit as String: kSecMatchLimitOne
    ]

    var dataTypeRef: AnyObject?
    let status: OSStatus = SecItemCopyMatching(query as CFDictionary, &dataTypeRef)

    if status == noErr {
        return dataTypeRef as? Data
    } else {
        return nil
    }
}

5. 輸入驗證與清理

對使用者輸入進行驗證和清理,防止XSS(跨站指令碼攻擊)和其他注入攻擊。

示例程式碼:

func sanitize(userInput: String) -> String {
    // Remove any script tags or other potentially dangerous content
    return userInput.replacingOccurrences(of: "<script>", with: "", options: .caseInsensitive)
                    .replacingOccurrences(of: "</script>", with: "", options: .caseInsensitive)
}

// Usage
let userInput = "<script>alert('xss')</script>"
let sanitizedInput = sanitize(userInput: userInput)
print(sanitizedInput) // Outputs: alert('xss')

OC版

1. 使用HTTPS

確保所有的網路請求都使用HTTPS協議,以加密資料傳輸,防止中間人攻擊。

示例程式碼:

Info.plist中配置App Transport Security (ATS):

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <false/>
</dict>

2. SSL Pinning

透過SSL Pinning可以確保應用程式只信任指定的伺服器證書,防止被劫持到偽造的伺服器。

示例程式碼:

#import <Foundation/Foundation.h>

@interface URLSessionPinningDelegate : NSObject <NSURLSessionDelegate>

@end

@implementation URLSessionPinningDelegate

- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * _Nullable credential))completionHandler {
    if ([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
        SecTrustRef serverTrust = challenge.protectionSpace.serverTrust;
        SecCertificateRef serverCertificate = SecTrustGetCertificateAtIndex(serverTrust, 0);
        
        NSString *certPath = [[NSBundle mainBundle] pathForResource:@"your_cert" ofType:@"cer"];
        NSData *localCertData = [NSData dataWithContentsOfFile:certPath];
        NSData *serverCertData = (__bridge NSData *)(SecCertificateCopyData(serverCertificate));
        
        if ([localCertData isEqualToData:serverCertData]) {
            NSURLCredential *credential = [NSURLCredential credentialForTrust:serverTrust];
            completionHandler(NSURLSessionAuthChallengeUseCredential, credential);
            return;
        }
    }
    completionHandler(NSURLSessionAuthChallengeCancelAuthenticationChallenge, nil);
}

@end

// Usage
NSURL *url = [NSURL URLWithString:@"https://yoursecurewebsite.com"];
NSURLSessionConfiguration *sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration];
URLSessionPinningDelegate *pinningDelegate = [[URLSessionPinningDelegate alloc] init];
NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfig delegate:pinningDelegate delegateQueue:nil];

NSURLSessionDataTask *task = [session dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    if (error == nil) {
        // Handle response
    }
}];
[task resume];

3. 防止SQL隱碼攻擊

在處理使用者輸入時,使用引數化查詢來防止SQL隱碼攻擊。

示例程式碼:

#import <sqlite3.h>

- (void)queryDatabase:(NSString *)userInput {
    sqlite3 *db;
    // Open database (assuming dbPath is the path to your database)
    if (sqlite3_open([dbPath UTF8String], &db) == SQLITE_OK) {
        sqlite3_stmt *statement;
        const char *query = "SELECT * FROM users WHERE username = ?";
        
        if (sqlite3_prepare_v2(db, query, -1, &statement, NULL) == SQLITE_OK) {
            sqlite3_bind_text(statement, 1, [userInput UTF8String], -1, SQLITE_TRANSIENT);
            
            while (sqlite3_step(statement) == SQLITE_ROW) {
                // Process results
            }
        }
        
        sqlite3_finalize(statement);
        sqlite3_close(db);
    }
}

4. Data Encryption

在儲存敏感資料時,使用iOS的加密庫來加密資料,比如使用Keychain

示例程式碼:

#import <Security/Security.h>

- (OSStatus)saveToKeychainWithKey:(NSString *)key data:(NSData *)data {
    NSDictionary *query = @{(__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
                            (__bridge id)kSecAttrAccount: key,
                            (__bridge id)kSecValueData: data};
    
    SecItemDelete((__bridge CFDictionaryRef)query); // Delete any existing item
    return SecItemAdd((__bridge CFDictionaryRef)query, NULL); // Add new item
}

- (NSData *)loadFromKeychainWithKey:(NSString *)key {
    NSDictionary *query = @{(__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
                            (__bridge id)kSecAttrAccount: key,
                            (__bridge id)kSecReturnData: (__bridge id)kCFBooleanTrue,
                            (__bridge id)kSecMatchLimit: (__bridge id)kSecMatchLimitOne};
    
    CFTypeRef dataTypeRef = NULL;
    OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)query, &dataTypeRef);
    
    if (status == noErr) {
        return (__bridge_transfer NSData *)dataTypeRef;
    } else {
        return nil;
    }
}

5. 輸入驗證與清理

對使用者輸入進行驗證和清理,防止XSS(跨站指令碼攻擊)和其他注入攻擊。

示例程式碼:

- (NSString *)sanitize:(NSString *)userInput {
    // Remove any script tags or other potentially dangerous content
    NSString *sanitizedInput = [userInput stringByReplacingOccurrencesOfString:@"<script>" withString:@"" options:NSCaseInsensitiveSearch range:NSMakeRange(0, userInput.length)];
    sanitizedInput = [sanitizedInput stringByReplacingOccurrencesOfString:@"</script>" withString:@"" options:NSCaseInsensitiveSearch range:NSMakeRange(0, sanitizedInput.length)];
    return sanitizedInput;
}

// Usage
NSString *userInput = @"<script>alert('xss')</script>";
NSString *sanitizedInput = [self sanitize:userInput];
NSLog(@"%@", sanitizedInput); // Outputs: alert('xss')

透過這些措施,你可以顯著提升iOS應用的網路安全性。根據專案需求,靈活運用這些技術以確保使用者資料的安全。

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