iPhone 上 NSString 的 AES 加密

使用AES加密在iPhone上对NSString进行加密是一种常见的安全措施。AES（Advanced Encryption Standard）是一种对称加密算法，被广泛应用于数据加密和保护领域。在iOS开发中，我们可以使用CommonCrypto库中的函数来实现AES加密和解密操作。

Objective-C
#import 

Objective-C
- (NSString *)AES128Encrypt:(NSString *)plainText withKey:(NSString *)key {
    NSData *plainData = [plainText dataUsingEncoding:NSUTF8StringEncoding];
    NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t iv[kCCBlockSizeAES128];
    memset((void *) iv, 0x0, (size_t) sizeof(iv));
    size_t bufferSize = plainData.length + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                          kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding,
                                          keyData.bytes,
                                          kCCKeySizeAES128,
                                          iv,
                                          plainData.bytes,
                                          plainData.length,
                                          buffer,
                                          bufferSize,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *encryptedData = [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
        return [encryptedData base64EncodedStringWithOptions:0];
    }
    free(buffer);
    return nil;
}

Objective-C
- (NSString *)AES128Decrypt:(NSString *)encryptedText withKey:(NSString *)key {
    NSData *encryptedData = [[NSData alloc] initWithBase64EncodedString:encryptedText options:0];
    NSData *keyData = [key dataUsingEncoding:NSUTF8StringEncoding];
    uint8_t iv[kCCBlockSizeAES128];
    memset((void *) iv, 0x0, (size_t) sizeof(iv));
    size_t bufferSize = encryptedData.length + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    size_t numBytesDecrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          kCCAlgorithmAES128,
                                          kCCOptionPKCS7Padding,
                                          keyData.bytes,
                                          kCCKeySizeAES128,
                                          iv,
                                          encryptedData.bytes,
                                          encryptedData.length,
                                          buffer,
                                          bufferSize,
                                          &numBytesDecrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *decryptedData = [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
        return [[NSString alloc] initWithData:decryptedData encoding:NSUTF8StringEncoding];
    }
    free(buffer);
    return nil;
}

Objective-C
NSString *username = @"exampleUsername";
NSString *password = @"examplePassword";
NSString *encryptionKey = @"exampleEncryptionKey";
NSString *encryptedUsername = [self AES128Encrypt:username withKey:encryptionKey];
NSString *encryptedPassword = [self AES128Encrypt:password withKey:encryptionKey];
// 将加密后的用户名和密码存储到数据库或服务器
// ...
// 当用户进行登录操作时，从数据库或服务器中获取加密的用户名和密码
NSString *encryptedUsernameFromDB = @"encryptedUsernameFromDB";
NSString *encryptedPasswordFromDB = @"encryptedPasswordFromDB";
NSString *decryptedUsername = [self AES128Decrypt:encryptedUsernameFromDB withKey:encryptionKey];
NSString *decryptedPassword = [self AES128Decrypt:encryptedPasswordFromDB withKey:encryptionKey];
// 使用解密后的用户名和密码进行用户身份验证
// ...