This is an application that will generate a valid machineKey block with random, secure, hard-coded keys that you can paste inside the <system.web> in your web.config or machine.config file.

Hard-coded encryption and validation keys are needed if you have a web farm/web garden, if you use passwordFormat=Encrypted with ASP.NET 2.0’s Membership provider, or if you have certain ViewState issues. I discuss those reasons more in-depth in my blog posts about “Invalid Viewstate” errors and the ASP.NET Membership Encrypted passwordFormat, or you can also read my machineKey CodeProject article for more background information.

Below is a random set of keys, generated by this page. Go ahead and refresh this page to get a new set of keys.

ASP.NET 1.1 machineKey

<machineKey validationKey="E9A84990B760092926ABF3F8C1CE0D638435627ECE4D57641F7C1C6C9114DC2C9E9F0722169BDB813B19064B27225BA69DC28FAC10E30409BFEBCDC89BB5C2DF"
 decryptionKey="37BDBF16362B926894E09B484B06275D86A82C1D0E9C39C0"
 validation="SHA1" />

ASP.NET 2.0 machineKey

<machineKey validationKey="972654F0AD520401A8113CFDCE02E91C5BBC97F9975B9472995658D3E2F6C449D9E80AE31E5721CD8D812750AAFA10E425D28CC5DA7CDC1AAF045572D12F8241"
 decryptionKey="D608AE9428B9400763CF2B133F7E062117B48C5DB758736051F6B6AAACAA5197"
 validation="SHA1" decryption="AES" />

If you want, you can also use the code below so you can generate the keys yourself:

using System;
using System.Text;
using System.Security;
using System.Security.Cryptography;

private void Button1_Click(object sender, System.EventArgs e)
{
	txtASPNET20.Text = getASPNET20machinekey();
	txtASPNET11.Text = getASPNET11machinekey();
}

public string getASPNET20machinekey()
{
	StringBuilder aspnet20machinekey = new StringBuilder();
	string key64byte = getRandomKey(64);
	string key32byte = getRandomKey(32);
	aspnet20machinekey.Append("\n");
	return aspnet20machinekey.ToString();
}

public string getASPNET11machinekey()
{
	StringBuilder aspnet11machinekey = new StringBuilder();
	string key64byte = getRandomKey(64);
	string key24byte = getRandomKey(24);

	aspnet11machinekey.Append("\n");
	return aspnet11machinekey.ToString();
}

public string getRandomKey(int bytelength)
{
	int len = bytelength * 2;
	byte[] buff = new byte[len / 2];
	RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
	rng.GetBytes(buff);
	StringBuilder sb = new StringBuilder(len);
	for (int i = 0; i < buff.Length; i++)
		sb.Append(string.Format("{0:X2}", buff[i]));
	return sb.ToString();
}