Objective-C中如何进行加密解密操作

Objective-C中可以使用CommonCrypto框架中的加密算法来进行加密和解密操作。以下是一个示例代码：

#import <CommonCrypto/CommonCrypto.h>

// 加密操作
- (NSData *)encryptData:(NSData *)data withKey:(NSString *)key {
    NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
    NSMutableData *encryptedData = [NSMutableData dataWithLength:data.length + kCCBlockSizeAES128];
    
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                          kCCAlgorithmAES,
                                          kCCOptionPKCS7Padding,
                                          keyData.bytes,
                                          keyData.length,
                                          NULL,
                                          data.bytes,
                                          data.length,
                                          encryptedData.mutableBytes,
                                          encryptedData.length,
                                          &numBytesEncrypted);
    
    if (cryptStatus == kCCSuccess) {
        encryptedData.length = numBytesEncrypted;
        return encryptedData;
    }
    
    return nil;
}

// 解密操作
- (NSData *)decryptData:(NSData *)data withKey:(NSString *)key {
    NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
    NSMutableData *decryptedData = [NSMutableData dataWithLength:data.length + kCCBlockSizeAES128];
    
    size_t numBytesDecrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          kCCAlgorithmAES,
                                          kCCOptionPKCS7Padding,
                                          keyData.bytes,
                                          keyData.length,
                                          NULL,
                                          data.bytes,
                                          data.length,
                                          decryptedData.mutableBytes,
                                          decryptedData.length,
                                          &numBytesDecrypted);
    
    if (cryptStatus == kCCSuccess) {
        decryptedData.length = numBytesDecrypted;
        return decryptedData;
    }
    
    return nil;
}

在上面的示例中，我们使用AES算法对数据进行加密和解密操作。需要注意的是，在实际使用时，需要将key参数替换为一个安全的密钥。