Help!!! how to correct the errors linked to class?

mark103 (39)
Hi guys,

I need your help. I am trying to build a Win32 project under Windows XP using managed C++ 2005 Express Edition. I have a bit of trouble with the errors. I am trying to linked the code to the class library, but i couldn't be able to find the solutions to get rid of the errors.

error C2227: left of '->Decrypt' must point to class/struct/union/generic type


The error are linked to the line:

if (plainText->Text == enc->Decrypt(key, "key123456"))


And I also get another error using with the same line:

error C3845: 'myapplication::Form1::key': only static data members can be initialized inside a ref class or value type

String ^key = "MoY3fOB+LbiQy6V3R35FASSmy";


here's the current code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
 
#pragma once

#include "Class1.h"


namespace myapplication {

    using namespace System;
    using namespace System::Collections::Generic;
    using namespace System::Text;
    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;
            }
        }
    internal: System::Windows::Forms::Label^  label2;
    protected:
    internal: System::Windows::Forms::Button^  Button1;
    internal: System::Windows::Forms::TextBox^  plainText;

    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->label2 = (gcnew System::Windows::Forms::Label());
            this->Button1 = (gcnew System::Windows::Forms::Button());
            this->plainText = (gcnew System::Windows::Forms::TextBox());
            this->SuspendLayout();
            //
            // label2
            //
            this->label2->AutoSize = true;
            this->label2->Location = System::Drawing::Point(24, 46);
            this->label2->Name = L"label2";
            this->label2->Size = System::Drawing::Size(302, 13);
            this->label2->TabIndex = 6;
            this->label2->Text = L"Do you know what the password is\? if so please enter it here...";
            //
            // Button1
            //
            this->Button1->Location = System::Drawing::Point(122, 101);
            this->Button1->Name = L"Button1";
            this->Button1->Size = System::Drawing::Size(96, 34);
            this->Button1->TabIndex = 5;
            this->Button1->Text = L"Confirm password!";
            this->Button1->UseVisualStyleBackColor = true;
            this->Button1->Click += gcnew System::EventHandler(this, &Form1::Button1_Click);
            //
            // plainText
            //
            this->plainText->Location = System::Drawing::Point(27, 65);
            this->plainText->Name = L"plainText";
            this->plainText->Size = System::Drawing::Size(292, 20);
            this->plainText->TabIndex = 4;
            //
            // Form1
            //
            this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
            this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
            this->ClientSize = System::Drawing::Size(341, 162);
            this->Controls->Add(this->label2);
            this->Controls->Add(this->Button1);
            this->Controls->Add(this->plainText);
            this->MaximizeBox = false;
            this->MinimizeBox = false;
            this->Name = L"Form1";
            this->SizeGripStyle = System::Windows::Forms::SizeGripStyle::Hide;
            this->StartPosition = System::Windows::Forms::FormStartPosition::CenterScreen;
            this->Text = L"myapplication";
            this->Load += gcnew System::EventHandler(this, &Form1::Form1_Load);
            this->ResumeLayout(false);
            this->PerformLayout();

        }
#pragma endregion

    myapplication ::Class1 ^enc();
    myapplication ::Class1 ^dec();
    String ^key = "MoY3fOB+LbiQy6V3R35FASSmy";

    private: System::Void Form1_Load(System::Object^  sender, System::EventArgs^  e) {
                 this->Select();
             }
    private: System::Void Button1_Click(System::Object^  sender, System::EventArgs^  e) {
                 if (plainText->Text == enc->Decrypt(key, "key123456"))
                 {
                     MessageBox::Show("the password is correct!");
                 }
                 else
                 {
                     MessageBox::Show("the password is incorrect");
                 }
             }
    };
}


I have input the "include class.h" on the top of the header, but it doesn't help me to get correct the errors. And also I cannot understand the second error I have got which I created the name of the string.

Can somebody please tell me how to fix those errors?

Any advice would be much appreciated.

Thanks in advance.
hamsterman (4538)
The first one is probably due to () after declarations of enc and dec which make the compiler think they're functions.
The second one is probably because you're initializing a member of a class in the wrong place. You have to do it in the constructor.
mark103 (39)
Thanks for your help hamsterman. I can see the problem is solve. I have ran the debug and when I clicked on the button, I get an unhandled exception error of System.NullReferenceException.

Here's the full error I get:


An unhandled exception of type 'System.NullReferenceException' occurred in myapplication.exe

Additional information: Object reference not set to an instance of an object.



The error are linked to this line:

 
 
this->algo->IV = encIv;



Here's the current code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
 
using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Diagnostics;
using namespace System::Collections::Generic;
using namespace System::Text;

namespace myapplication {

	/// <summary>
	/// Summary for Class1
	/// </summary>
	public ref class Class1 :  public System::ComponentModel::Component
	{
	public:
		Class1(void)
		{
			InitializeComponent();
			//
			//TODO: Add the constructor code here
			//
		}
		Class1(System::ComponentModel::IContainer ^container)
		{
			/// <summary>
			/// Required for Windows.Forms Class Composition Designer support
			/// </summary>

			container->Add(this);
			InitializeComponent();
		}

	protected:
		/// <summary>
		/// Clean up any resources being used.
		/// </summary>
		~Class1()
		{
			if (components)
			{
				delete components;
			}
		}

	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)
		{
			components = gcnew System::ComponentModel::Container();
		}
#pragma endregion


	public: void PolyAES()
	{
		this->algo = gcnew System::Security::Cryptography::RijndaelManaged();
		this->algo->Mode = System::Security::Cryptography::CipherMode::CBC;
		this->rngAlgo = gcnew System::Security::Cryptography::RNGCryptoServiceProvider();
	}

private:
	literal int saltSize = 32;

	System::Security::Cryptography::SymmetricAlgorithm ^algo;
	System::Security::Cryptography::RNGCryptoServiceProvider ^rngAlgo;
	array<Byte> ^salt;



private:
	void InitializeSecureParameters(array<Byte> ^key)
	{
		// init rijndael IV
		this->algo->GenerateIV();
		salt = gcnew array<Byte>(saltSize);
		rngAlgo->GetBytes(salt);
		System::Security::Cryptography::Rfc2898DeriveBytes ^pwDeriveAlg = gcnew System::Security::Cryptography::Rfc2898DeriveBytes(key, salt, 2000);
		this->algo->Key = pwDeriveAlg->GetBytes(32);
	}

	void LoadSecureParameters(array<Byte> ^key, array<Byte> ^encIv, array<Byte> ^encSalt)
	{
		this->algo->IV = encIv;
		this->salt = encSalt;
		System::Security::Cryptography::Rfc2898DeriveBytes ^pwDeriveAlg = gcnew System::Security::Cryptography::Rfc2898DeriveBytes(key, salt, 2000);
		this->algo->Key = pwDeriveAlg->GetBytes(32);
	}

public:
	String ^Encrypt(String ^plainText, String ^key)
	{
		return Convert::ToBase64String(this->Encrypt(UnicodeEncoding::UTF8->GetBytes(plainText), UnicodeEncoding::UTF8->GetBytes(key)));
	}

	String ^Decrypt(String ^cipherText, String ^key)
	{
		return UnicodeEncoding::UTF8->GetString(this->Decrypt(Convert::FromBase64String(cipherText), UnicodeEncoding::UTF8->GetBytes(key)));
	}

	array<Byte> ^Encrypt(array<Byte> ^plainText, array<Byte> ^key)
	{
		InitializeSecureParameters(key);
		System::Security::Cryptography::ICryptoTransform ^encTransform = algo->CreateEncryptor();
		return ConcatDataToCipherText(ConcatDataToCipherText(encTransform->TransformFinalBlock(plainText, 0, plainText->Length), salt), algo->IV);
	}

	array<Byte> ^Decrypt(array<Byte> ^cipherText, array<Byte> ^key)
	{
		array<Byte> ^cipherTextWithSalt = gcnew array<Byte>(1);
		array<Byte> ^encSalt = gcnew array<Byte>(1);
		array<Byte> ^origCipherText = gcnew array<Byte>(1);
		array<Byte> ^encIv = gcnew array<Byte>(1);

		SliceCipherTextIntoParts(cipherText, 16, cipherTextWithSalt, encIv);
		SliceCipherTextIntoParts(cipherTextWithSalt, saltSize, origCipherText, encSalt);
		LoadSecureParameters(key, encIv, encSalt);
		System::Security::Cryptography::ICryptoTransform ^decTransform = algo->CreateDecryptor();
		array<Byte> ^plainText = decTransform->TransformFinalBlock(origCipherText, 0, origCipherText->Length);

		return plainText;
	}

private:
	array<Byte> ^ConcatDataToCipherText(array<Byte> ^cipherText, array<Byte> ^iv)
	{
		int origLength = cipherText->Length;
		Array::Resize(cipherText, cipherText->Length + iv->Length);
		Buffer::BlockCopy(iv, 0, cipherText, origLength, iv->Length);
		return cipherText;
	}
	void SliceCipherTextIntoParts(array<Byte> ^cipherText, int secondPartLen, array<Byte> ^%origCipherText, array<Byte> ^%iv)
	{
		Array::Resize(iv, secondPartLen);
		Buffer::BlockCopy(cipherText, Convert::ToInt32(cipherText->Length - secondPartLen), iv, 0, secondPartLen);
		Array::Resize(origCipherText, Convert::ToInt32(cipherText->Length - secondPartLen));
		Buffer::BlockCopy(cipherText, 0, origCipherText, 0, Convert::ToInt32(cipherText->Length - secondPartLen));
	}

	};
}



Any idea how to fix the error?
hamsterman (4538)
It seems that this->algo is null. You need to do algo = new SymetricAlgorithm(???) at some point. Whre that is appropriate is for you to decide.
mark103 (39)
Thanks, how do i find out with the variable whether if this->algo is null or not? do i have to do the breakpoint?
hamsterman (4538)
if (algo == nullptr) ..., at least that's what a quick google search gave me.
Topic archived. No new replies allowed.