Writing a Specific CRC32 Signature on a File

Just say I know the CRC32 Signature that I want to put on my file but I don't know how to specify it in my code so that when it signs the file it signs it using that specific signature that I specified, like if I open a file called "dune.map" and I know that the signature is supposed to be "DE545GHJ" how would I put that in my code so that when I click "sign" it signs the file using that specific signature, but then I want to open another file called "backwash.map" and I know that the signature for that file is "DDFGSFFG" how would I specify it in the code so that when I want to sign it it signs it with that signature In other words I want my program to sign different files using the signatures that I specify. Here's my code so far:

pragma once

namespace CRC32 {

using namespace System;

using namespace System::ComponentModel;

using namespace System::Collections;

using namespace System::Windows::Forms;

using namespace System::Data;

using namespace System::Drawing;

/// <summary>

/// Summary for Form1

///

/// WARNING: If you change the name of this class, you will need to change the

/// 'Resource File Name' property for the managed resource compiler tool

/// associated with all .resx files this class depends on. Otherwise,

/// the designers will not be able to interact properly with localized

/// resources associated with this form.

/// </summary>

public ref class Form1 : public System::Windows::Forms::Form

{

public:

Form1(void)

{

InitializeComponent();

//TODO: Add the constructor code here

}

protected:

/// <summary>

/// Clean up any resources being used.

/// </summary>

~Form1()

{

if (components)

{

delete components;

}

private: System::Windows::Forms::Button^ button1;

protected:

private: System::Windows::Forms::ListBox^ listBox1;

private: System::Windows::Forms::OpenFileDialog^ openFileDialog1;

private: System::Windows::Forms::Button^ button2;

private: System::Windows::Forms::Button^ button3;

private: System::Windows::Forms::Button^ button4;

private: System::Windows::Forms::Button^ button5;

private:

/// <summary>

/// Required designer variable.

/// </summary>

System::ComponentModel::Container ^components;

#pragma region Windows Form Designer generated code

/// <summary>

/// Required method for Designer support - do not modify

/// the contents of this method with the code editor.

/// </summary>

void InitializeComponent(void)

{

this->button1 = (gcnew System::Windows::Forms::Button());

this->listBox1 = (gcnew System::Windows::Forms::ListBox());

this->openFileDialog1 = (gcnew System::Windows::Forms::OpenFileDialog());

this->button2 = (gcnew System::Windows::Forms::Button());

this->button3 = (gcnew System::Windows::Forms::Button());

this->button4 = (gcnew System::Windows::Forms::Button());

this->button5 = (gcnew System::Windows::Forms::Button());

this->SuspendLayout();

// button1

this->button1->Location = System::Drawing::Point(12, 12);

this->button1->Name = L"button1";

this->button1->Size = System::Drawing::Size(75, 23);

this->button1->TabIndex = 0;

this->button1->Text = L"Open";

this->button1->UseVisualStyleBackColor = true;

this->button1->Click += gcnew System::EventHandler(this, &Form1::button1_Click);

// listBox1

this->listBox1->BackColor = System::Drawing::SystemColors::WindowFrame;

this->listBox1->ForeColor = System::Drawing::SystemColors::Window;

this->listBox1->FormattingEnabled = true;

this->listBox1->Location = System::Drawing::Point(12, 41);

this->listBox1->Name = L"listBox1";

this->listBox1->Size = System::Drawing::Size(320, 186);

this->listBox1->TabIndex = 3;

// openFileDialog1

this->openFileDialog1->FileName = L"openFileDialog1";

// button2

this->button2->Location = System::Drawing::Point(93, 12);

this->button2->Name = L"button2";

this->button2->Size = System::Drawing::Size(75, 23);

this->button2->TabIndex = 4;

this->button2->Text = L"Close";

this->button2->UseVisualStyleBackColor = true;

this->button2->Click += gcnew System::EventHandler(this, &Form1::button2_Click);

// button3

this->button3->Location = System::Drawing::Point(176, 12);

this->button3->Name = L"button3";

this->button3->Size = System::Drawing::Size(75, 23);

this->button3->TabIndex = 5;

this->button3->Text = L"Check";

this->button3->UseVisualStyleBackColor = true;

this->button3->Click += gcnew System::EventHandler(this, &Form1::button3_Click);

// button4

this->button4->Location = System::Drawing::Point(257, 12);

this->button4->Name = L"button4";

this->button4->Size = System::Drawing::Size(75, 23);

this->button4->TabIndex = 6;

this->button4->Text = L"Sign";

this->button4->UseVisualStyleBackColor = true;

this->button4->Click += gcnew System::EventHandler(this, &Form1::button4_Click);

// button5

this->button5->Location = System::Drawing::Point(255, 233);

this->button5->Name = L"button5";

this->button5->Size = System::Drawing::Size(75, 23);

this->button5->TabIndex = 7;

this->button5->Text = L"Exit";

this->button5->UseVisualStyleBackColor = true;

this->button5->Click += gcnew System::EventHandler(this, &Form1::button5_Click);

// Form1

this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);

this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;

this->ClientSize = System::Drawing::Size(342, 266);

this->Controls->Add(this->button5);

this->Controls->Add(this->button4);

this->Controls->Add(this->button3);

this->Controls->Add(this->button2);

this->Controls->Add(this->listBox1);

this->Controls->Add(this->button1);

this->Name = L"Form1";

this->Text = L"CRC32";

this->ResumeLayout(false);

}

#pragma endregion

private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) {

openFileDialog1->Title = "Select a File";

openFileDialog1->Filter = "All Files(*.*)|*.*";

openFileDialog1->FileName = "";

openFileDialog1->Multiselect = true;

if(openFileDialog1->ShowDialog() == System::Windows::Forms::DialogResult::OK)

listBox1->Items->AddRange(openFileDialog1->FileNames);

}

private: System::Void button2_Click(System::Object^ sender, System::EventArgs^ e) {

int nCount = listBox1->Items->Count;

for(int nIndex = nCount - 1; nIndex >= 0; nIndex--)

if(listBox1->SelectedIndices->Contains(nIndex))

listBox1->Items->RemoveAt(nIndex);

}

private: System::Void button3_Click(System::Object^ sender, System::EventArgs^ e) {

}

private: System::Void button4_Click(System::Object^ sender, System::EventArgs^ e) {

System::DateTime dtStart = System::DateTime::Now;

for each(String ^sFile in listBox1->Items)

{

System::IO::FileStream ^fs = gcnew System::IO::FileStream(sFile, System::IO::FileMode::Open, System::IO::FileAccess::ReadWrite, System::IO::FileShare::Read);

if(fs->Length % 4 != 0)

{

MessageBox::Show("The selected file(s) " + sFile + " is/are not bounded to four...I apologize, but the file will not be signed.", "CRC32", MessageBoxButtons::OK, MessageBoxIcon::Exclamation);

continue;

}

int nChecksum = 0;

System::IO::BinaryReader ^br = gcnew System::IO::BinaryReader(fs);

br->BaseStream->Position = 0x800;

int nEndOfFile = safe_cast<int>(fs->Length);

for(int x = 0x800; x < nEndOfFile; x += 4)

nChecksum ^= br->ReadInt32();

fs->Position = 0x2d0;

fs->Write(BitConverter::GetBytes(nChecksum), 0, 4);

br->Close();

fs->Close();

fs = nullptr;

}

MessageBox::Show("Complete!\nStart Time: " + dtStart.ToString() + "\nFinish Time: " + System::DateTime::Now.ToString(), "CRC32", MessageBoxButtons::OK, MessageBoxIcon::Information);

}

private: System::Void button5_Click(System::Object^ sender, System::EventArgs^ e) {

Close();

}

};

}

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