iphone - 在 IOS 中实现 AES256 加密

Question

这是我的java代码。现在我想在 Objective-C 中实现相同的功能。

Cipher encryptCipher;
IvParameterSpec iv = new IvParameterSpec(key);
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
encryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
encryptCipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = encryptCipher.doFinal(dataToEncrypt.getBytes());
Log.d("TAG", "encrypted string:"
        + Base64.encodeToString(encrypted, Base64.DEFAULT));
return Base64.encodeToString(encrypted, Base64.DEFAULT).trim();

这是我的 iOS 实现

- (NSData *)AES256EncryptWithKey:(NSString*)key
{
    char keyPtr[kCCKeySizeAES256 + 1];
    bzero(keyPtr, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSUInteger dataLength = [self length];

    size_t bufferSize           = dataLength + kCCBlockSizeAES128;
    void* buffer                = malloc(bufferSize);

    size_t numBytesEncrypted    = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                  kCCAlgorithmAES128,
                                  kCCOptionPKCS7Padding,
                                  keyPtr,
                                  kCCKeySizeAES256,
                                  NULL,
                                  [self bytes],
                                  dataLength,
                                  buffer,
                                  bufferSize, 
                                  &numBytesEncrypted);

    if (cryptStatus == kCCSuccess)
    {

        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }

    free(buffer);
    return nil;
}

这是我的哈希 key 生成函数。此函数在 android 和 ios 中返回相同的 key

int dkLen = 16;
    NSData *keyData = [hash_key dataUsingEncoding:NSUTF8StringEncoding];
    NSData *salt    = [saltKey dataUsingEncoding:NSUTF8StringEncoding];
    uint    rounds  = 1000;
    uint    keySize = kCCKeySizeAES128;

    NSMutableData *derivedKey = [NSMutableData dataWithLength:keySize];





    CCKeyDerivationPBKDF(kCCPBKDF2,               // algorithm
                         keyData.bytes,           // password
                         keyData.length,          // passwordLength
                         salt.bytes,              // salt
                         salt.length,             // saltLen
                         kCCPRFHmacAlgSHA1,       // PRF
                         rounds,                  // rounds
                         derivedKey.mutableBytes, // derivedKey
                         dkLen*8);
 return derivedKey;

我得到了不同的输出。我做错了什么吗？请帮我找出答案。

Answer 1

一个问题是Java代码使用CBC模式，iOS代码使用ECB模式。

接下来，从引用的项目:
//结果= yHbhApwTpQ2ZhE97AKF/g==
无效的 Base64，它不包含 4 字节的倍数。

使用这些选项:CBC、PKCS#7 填充

inputs:     data in: "hello" which will be null padded to the block length of 16-bytes     key:        base64: VQQhu+dUdqXGoE7RZL2JWg==        hex: 550421bbe75476a5c6a04ed164bd895a     iv:         base64: VQQhu+dUdqXGoE7RZL2JWg==        hex: 550421bbe75476a5c6a04ed164bd895a  encrypted output:     hex: ff21db840a704e943666113dec0285fe     base64: /yHbhApwTpQ2ZhE97AKF/g==  

This is the test code:

NSString *base64Key  = @"VQQhu+dUdqXGoE7RZL2JWg==";
NSString *dataString = @"hello";

NSData *key  = [[NSData alloc] initWithBase64EncodedString:base64Key  options:0];
NSData *data = [dataString dataUsingEncoding:NSUTF8StringEncoding];

NSLog(@"key:  %@", key);
NSLog(@"data: %@", data);

NSData *encryptedData = [TestClass crypt:data
                                 iv:key
                                key:key
                            context:kCCEncrypt];

NSLog(@"encryptedData: %@", encryptedData);
NSString *encryptedBase64Data = [encryptedData base64EncodedStringWithOptions:0];
NSLog(@"encryptedBase64Data: %@", encryptedBase64Data);

这是加密方法(在TestClass类中):

+ (NSData *)crypt:(NSData *)dataIn
                  iv:(NSData *)iv
                 key:(NSData *)symmetricKey
             context:(CCOperation)encryptOrDecrypt
{
    CCCryptorStatus ccStatus   = kCCSuccess;
    size_t          cryptBytes = 0;    // Number of bytes moved to buffer.
    NSMutableData  *dataOut    = [NSMutableData dataWithLength:dataIn.length + kCCBlockSizeAES128];

    ccStatus = CCCrypt( encryptOrDecrypt,
                       kCCAlgorithmAES128,
                       kCCOptionPKCS7Padding,
                       symmetricKey.bytes,
                       kCCKeySizeAES128,
                       iv.bytes,
                       dataIn.bytes,
                       dataIn.length,
                       dataOut.mutableBytes,
                       dataOut.length,
                       &cryptBytes);

    if (ccStatus != kCCSuccess) {
        NSLog(@"CCCrypt status: %d", ccStatus);
    }

    dataOut.length = cryptBytes;

    return dataOut;
}

注意:我将加密和数据转换分开。合并它们只会使测试变得更加复杂。

如果您使用在线加密实现，填充可能不是 PKCS#7，因为 mcrypt 不支持它，而是使用非标准空填充。由于填充字节只是填充字节的计数，因此可以在输入中模拟填充。这是使用 AES – Symmetric Ciphers Online 的示例

请注意，填充到 16 字节 block 大小的“hello”PKCS#7 添加了 11 个字节的 uint8 值 11 或 0x0B:68656c6c6f0B0B0B0B0B0B0B0B0B0B0B0B。

最后的问题仍然是为什么 Java 代码不会产生这个结果？