Question

目前我在C ++ / CLI代码中实现了一个返回文件SHA1值的函数。它是Visual Studio中的Windows窗体应用程序。

我选择实现.NetFramework类SHA1CryptoServiceProvider，因为它非常快（相信我）。我测试了几种算法，但没有一种算法和SHA1CryptoServiceProvider类一样快。

问题是在我的应用程序中有一个progressBar显示计算SHA1的进度，而SHA1CryptoServiceProvider类没有任何返回计算SHA1进度的函数。

以下是代码：

using namespace System::Security::Cryptography;
using namespace System::IO;

StreamReader^ Reader = gcnew StreamReader("C:\\abc.exe");
SHA1CryptoServiceProvider^ SHA1 = gcnew SHA1CryptoServiceProvider();

String^ Hash = "";

Hash = BitConverter::ToString(SHA1->ComputeHash(Reader->BaseStream));
return Hash;

Answer 1

最后我做到了。我发布了代码，也许有人会发现它很有用。我知道代码不干净，我还在学习。它可以计算大于2 ^ 31字节的文件的SHA1。在22GB文件上测试它。在后台正常工作：）

#define SHA1_BUFFER_SIZE  65535
//input buffer
array<unsigned char,1>^ buf = gcnew array<unsigned char,1>(SHA1_BUFFER_SIZE);
pin_ptr<unsigned char> pointer = &buf[0];

//Open file in 64-bit mode
FILE *file = _fopeni64("some_large_file.txt","rb");
SHA1CryptoServiceProvider^ SHA1 = gcnew SHA1CryptoServiceProvider();

//Move pointer to End of File
_fseeki64(file,0,SEEK_END);
//Read pointer position (file size)
unsigned __int64 size = (__int64)_ftelli64(file);

// Move pointer to begining of file
_fseeki64(file,0,SEEK_SET);
__int64 i = 1;    // counter
float wyn = 0;    // help variable for progress Percentage (float)
__int64 conv = 0; // help variable for progress Percentage (int)

//output buffer
array<unsigned char,1>^ outputbuffer = gcnew array<unsigned char,1>(SHA1_BUFFER_SIZE);
while(1)
{
    //Read SHA1_BUFFER_SIZE bytes to buffer
    size_t bufLen = fread( pointer, 1, SHA1_BUFFER_SIZE, file );
    if (bufLen == 0) //End of file
    {
        if (ferror(file)) //Error opening file
            return;
        break;
    }
    //buffer has the last block of bytes of the file
    if ( SHA1_BUFFER_SIZE*i >= size  )
        SHA1->TransformFinalBlock(buf,0,bufLen);
    else
        SHA1->TransformBlock(buf,0,bufLen,outputbuffer,0);

    wyn = SHA1_BUFFER_SIZE*100; /* Getting    */
    wyn /= size;                /* the        */
    wyn *= i;                   /* progress   */
    conv = wyn;                 /* Percentage */
    ComputeSHA1->ReportProgress(conv);
    \\Update our progressBar
    i++;
} //End main loop

String^ sHash = "";
//Get the computed hash and convert to System::String
sHash = BitConverter::ToString(SHA1->Hash);
//Replace the '-' characters in hash to white spaces
sHash = sHash->Replace('-',' ');
//Removing whitespaces from hash
sHash = System::Text::RegularExpressions::Regex::Replace(sHash, "\\s+", System::String::Empty);

//Filling a textBox with the SHA1
ComputeSHA1->ReportProgress(0,sHash);

获取使用SHA1CryptoServiceProvider计算SHA1的进度

1 个答案: