Newbe KeygenMe1-App

[SaggingCoder]

Difficulty : 5
Language : .NET
Platform : Windows
OS Version : All
Packer / Protector : ConfuserEx - Custom

Description :
This is my first time as a newbe; I hope I didnt do too badly 😅. Try to find at least one valid alphanumeric Key. The key has the following format: XXXX-XXXX-XXXX-XXXX-XXXX-XXXX, it can have letters and numers. Good luck!

Screenshot :

KeygenMe1.zip

[Reza-HNA]

1/10, almost nothing moded

  Reveal hidden contents

private void button1_Click(object sender, EventArgs e)
{
	this.textBox1.Text.ToCharArray();
	if (this.textBox1.Text.Length == 29)
	{
		if (this.textBox1.Text.Contains("-") && this.textBox1.Text.ToCharArray()[4] == '-' && this.textBox1.Text.ToCharArray()[9] == '-' && this.textBox1.Text.ToCharArray()[14] == '-')
		{
			if (this.textBox1.Text.ToCharArray()[19] == '-')
			{
				if (this.textBox1.Text.ToCharArray()[24] == '-')
				{
					if (!this.method_0())
					{
						MessageBox.Show("Sorry Duke, wrong key. Try again!");
						return;
					}
					this.label2.Visible = true;
					return;
				}
			}
		}
	}
	MessageBox.Show("The entered Key doesnt have the correct format", ":(", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}

 

 

KeygenMe1-cleaned.zipFetching info...

Edited June 20, 2018 by Reza-HNA

[YuqseLx]

  On 6/20/2018 at 5:54 AM, Reza-HNA said:

1/10, almost nothing moded

  Reveal hidden contents

private void button1_Click(object sender, EventArgs e)
{
	this.textBox1.Text.ToCharArray();
	if (this.textBox1.Text.Length == 29)
	{
		if (this.textBox1.Text.Contains("-") && this.textBox1.Text.ToCharArray()[4] == '-' && this.textBox1.Text.ToCharArray()[9] == '-' && this.textBox1.Text.ToCharArray()[14] == '-')
		{
			if (this.textBox1.Text.ToCharArray()[19] == '-')
			{
				if (this.textBox1.Text.ToCharArray()[24] == '-')
				{
					if (!this.method_0())
					{
						MessageBox.Show("Sorry Duke, wrong key. Try again!");
						return;
					}
					this.label2.Visible = true;
					return;
				}
			}
		}
	}
	MessageBox.Show("The entered Key doesnt have the correct format", ":(", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}

 

 

KeygenMe1-cleaned.zipFetching info...

Expand  

Unpack is very easy you're right but how do keygen? I can't do that is that possible?

[SaggingCoder]

  On 6/20/2018 at 5:54 AM, Reza-HNA said:

1/10, almost nothing moded

  Reveal hidden contents

private void button1_Click(object sender, EventArgs e)
{
	this.textBox1.Text.ToCharArray();
	if (this.textBox1.Text.Length == 29)
	{
		if (this.textBox1.Text.Contains("-") && this.textBox1.Text.ToCharArray()[4] == '-' && this.textBox1.Text.ToCharArray()[9] == '-' && this.textBox1.Text.ToCharArray()[14] == '-')
		{
			if (this.textBox1.Text.ToCharArray()[19] == '-')
			{
				if (this.textBox1.Text.ToCharArray()[24] == '-')
				{
					if (!this.method_0())
					{
						MessageBox.Show("Sorry Duke, wrong key. Try again!");
						return;
					}
					this.label2.Visible = true;
					return;
				}
			}
		}
	}
	MessageBox.Show("The entered Key doesnt have the correct format", ":(", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}

 

 

KeygenMe1-cleaned.zipFetching info...

Expand  

Nice, I knew youd easily unpack it, however this wasnt the entire purpose of this challenge. I'm asking if you can figure out at least one Key or better even write a keygen to this little app 😉

[kao]

  On 6/20/2018 at 7:08 PM, SaggingCoder said:

I'm asking if you can figure out at least one Key or better even write a keygen to this little app

Expand  

Given the way you designed this app, I believe it is not keygenable.

Basically, what you're asking is this: "knowing the encrypted data and the original data, find the used encryption key".
It's called known-plaintext attack and it's practically impossible on modern algorithms like AES (when they are used in the way you did).

 

However, I'll be happy to be proven wrong..  

[SaggingCoder]

  On 6/20/2018 at 8:45 PM, kao said:

Given the way you designed this app, I believe it is not keygenable.

Basically, what you're asking is this: "knowing the encrypted data and the original data, find the used encryption key".
It's called known-plaintext attack and it's practically impossible on modern algorithms like AES (when they are used in the way you did).

 

However, I'll be happy to be proven wrong..  

Expand  

Oooooh ok, I understand and I apologize! I thought there still might be a way to somehow reverse the rijndael algorithm... (or if it's impossible, just bruteforcing until one key is found) Welp then here is one key: 8C08-UT01-70J9-9ST3-D416-09A0, writing a keygen shouldnt be too hard now

Edited June 20, 2018 by SaggingCoder

[kao]

..and with one known key it's perfectly solvable.

 

All credits go to @Reza-HNA for deobfuscating the keygenme. After that, it was a piece of cake. Keygen is not obfuscated in any way, so anyone can take a look how it's done.

keygen for Newbe KeygenMe1.zip

[lovejoy226]

How to unpack this target?

Regards.

sean.