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="8D1A62144C426CFBCB1518E72FAAF9C296ED823EA96CC5ED82300CDDCB26D219DEE4CEF1740DC9D6BB2078BC2104ADFB36E5C2516DBAE862AC0558765425F1D5"
 decryptionKey="47D27905B4696A151ECFDD3652F2A3BB71873DD09D7E60D7"
 validation="SHA1" />

ASP.NET 2.0 machineKey

<machineKey validationKey="3354EC4AEA73E07C889D10DDB5FA29EFA17F008E0EDC4DAD79E0FAC85B152E37EDCC19AE46EE9A02FA707BEDC38F4A5E329A6A517592D40CBE4060AD1A3B51E6"
 decryptionKey="B775507D88AB7A3CF8C82CA6B4A79CC8E6A7717BF2A509A6116FAA7D433FC854"
 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();
}