Question

我一直在尝试编写加密和解密函数，这些函数的签名要求输入，输出字符串只能是void*类型。如果输入可以指定为IBuffer^，则代码可以正常工作，但在另一种情况下，源字符串和加密的＆gt;解密字符串不匹配。

CodeIBuffer^ byteArrayToIBufferPtr(byte *source, int size)
{
    Platform::ArrayReference<uint8> blobArray(source, size);
    IBuffer ^buffer = CryptographicBuffer::CreateFromByteArray(blobArray);
    return buffer;
}

byte* IBufferPtrToByteArray(IBuffer ^buffer)
{
    Array<unsigned char,1U> ^platArray = ref new Array<unsigned char,1U>(256);
    CryptographicBuffer::CopyToByteArray(buffer,&platArray);

    byte *dest = platArray->Data;
    return dest;
}

int DataEncryption::encryptData(EncryptionAlgorithm algo, int keySize, void* srcData, const unsigned int srcSize,
        void*& encData, unsigned int& encSize)
{

    LOG_D(TAG, "encryptData()");

    if(srcData == nullptr)
    {
        LOG_E(TAG,"");
        return DataEncryption::RESULT_EMPTY_DATA_ERROR;
    }
    if(srcSize == 0)
    {
        LOG_E(TAG,"");
        return DataEncryption::RESULT_SIZE_ZERO_ERROR;
    }

    IBuffer^ encrypted;
    IBuffer^ buffer;
    IBuffer^ iv = nullptr;
    String^ algName;
    bool cbc = false;

    switch (algo)
    {
    case DataEncryption::ENC_DEFAULT:
        algName = "AES_CBC";
        cbc = true;
        break;
    default:
        break;
    }

    // Open the algorithm provider for the algorithm specified on input.
    SymmetricKeyAlgorithmProvider^ Algorithm = SymmetricKeyAlgorithmProvider::OpenAlgorithm(algName);

    // Generate a symmetric key.
    IBuffer^ keymaterial = CryptographicBuffer::GenerateRandom((keySize + 7) / 8);
    CryptographicKey^ key;

    try
    {
        key = Algorithm->CreateSymmetricKey(keymaterial);
    }
    catch(InvalidArgumentException^ e)
    {
        LOG_E(TAG,"encryptData(): Could not create key.");
        return DataEncryption::RESULT_ERROR;
    }

    // CBC mode needs Initialization vector, here just random data.
    // IV property will be set on "Encrypted".
    if (cbc)
        iv = CryptographicBuffer::GenerateRandom(Algorithm->BlockLength);

    // Set the data to encrypt. 
    IBuffer ^srcDataBuffer = byteArrayToIBufferPtr(static_cast<byte*>(srcData),256);

    // Encrypt and create an authenticated tag.
    encrypted = CryptographicEngine::Encrypt(key, srcDataBuffer, iv);

    //encData = encrypted;
    byte *bb = IBufferPtrToByteArray(encrypted);
    encData = IBufferPtrToByteArray(encrypted);
    encSize = encrypted->Length;

    return DataEncryption::RESULT_SUCCESS;
}


int DataEncryption::decryptData(EncryptionAlgorithm algo, int keySize, void* encData, const unsigned int encSize,
        void*& decData, unsigned int& decSize)
{
    LOG_D(TAG, "decryptData()");

    if(encData == nullptr)
    {
        LOG_E(TAG,"");
        return DataEncryption::RESULT_EMPTY_DATA_ERROR;
    }
    if(encSize == 0)
    {
        LOG_E(TAG,"");
        return DataEncryption::RESULT_SIZE_ZERO_ERROR;
    }

    IBuffer^ encrypted;
    IBuffer^ decrypted;
    IBuffer^ iv = nullptr;
    String^ algName;
    bool cbc = false;

    switch (algo)
    {
    case DataEncryption::ENC_DEFAULT:
        algName = "AES_CBC";
        cbc = true;
        break;
    default:
        break;
    }

    // Open the algorithm provider for the algorithm specified on input.
    SymmetricKeyAlgorithmProvider^ Algorithm = SymmetricKeyAlgorithmProvider::OpenAlgorithm(algName);

    // Generate a symmetric key.
    IBuffer^ keymaterial = CryptographicBuffer::GenerateRandom((keySize + 7) / 8);
    CryptographicKey^ key;

    try
    {
        key = Algorithm->CreateSymmetricKey(keymaterial);
    }
    catch(InvalidArgumentException^ e)
    {
        LOG_E(TAG,"encryptData(): Could not create key.");
        return DataEncryption::RESULT_ERROR;
    }

    // CBC mode needs Initialization vector, here just random data.
    // IV property will be set on "Encrypted".
    if (cbc)
        iv = CryptographicBuffer::GenerateRandom(Algorithm->BlockLength);

    // Set the data to decrypt. 
    byte *cc = static_cast<byte*>(encData);
    IBuffer ^encDataBuffer = byteArrayToIBufferPtr(cc,256);
    // Decrypt and verify the authenticated tag.
    decrypted = CryptographicEngine::Decrypt(key, encDataBuffer, iv);

    byte *bb = IBufferPtrToByteArray(decrypted);
    decData = IBufferPtrToByteArray(decrypted);

    decSize = decrypted->Length;

    return DataEncryption::RESULT_SUCCESS;
}

Answer 1

我猜测问题出在这个函数上：

byte* IBufferPtrToByteArray(IBuffer ^buffer)
{
    Array<unsigned char,1U> ^platArray = ref new Array<unsigned char,1U>(256);
    CryptographicBuffer::CopyToByteArray(buffer,&platArray);

    byte *dest = platArray->Data;
    return dest;
}

你正在做的是分配一个带有1个引用的新Platform::Array<byte>^，然后获取指向其内部管理存储的指针，然后返回该指针 - 此时数组被解除引用并且因此，解除分配其底层存储。因此，您返回的指针指的是释放的内存。下一个分配可能会覆盖这些字节。

您需要做的是从Array<byte>^获取引用CopyToByteArray()（它创建一个新数组，可能包含输入的字节IBuffer^ ，并返回它）并复制该数组的内容。

您的最终结果将与Readium SDK项目中的此片段功能类似，该项目采用std::string实例，使用SHA-1哈希，并将哈希数据复制到成员变量uint8_t _key[KeySize]：

using namespace ::Platform;
using namespace ::Windows::Foundation::Cryptography;
using namespace ::Windows::Foundation::Cryptography::Core;

auto byteArray = ArrayReference<byte>(reinterpret_cast<byte*>(const_cast<char*>(str.data())), str.length());
auto inBuf = CryptographicBuffer::CreateFromByteArray(byteArray);
auto keyBuf = HashAlgorithmProvider::OpenAlgorithm(HashAlgorithmNames::Sha1)->HashData(inBuf);

Array<byte>^ outArray = nullptr;
CryptographicBuffer::CopyToByteArray(keyBuf, &outArray);
memcpy_s(_key, KeySize, outArray->Data, outArray->Length);

步骤：

创建与ArrayReference<byte>中的字节对应的std::string（不复制）。
将其传递给CryptographicBuffer::CreateFromByteArray()以获取IBuffer^。仍然没有复制数据。
调用您的哈希/加密函数，传递您刚刚创建的IBuffer^。你得到了另一个IBuffer^作为回报，它可能使用或者没有使用完全相同的存储（我认为这实际上取决于算法的实现）。
创建Array<byte>^类型的变量。不要分配一个对象，你将通过引用给出一个。
将该对象的地址传递到CryptographicBuffer::CopyToByteArray()以接收关键数据的副本。
虽然Array^仍然有效，但将其字节复制到本机数组中。

如何在WinRT中加密和解密const char *

1 个答案: