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="7FCA79395D95E5A3E326224C10FDEBE2F70AAEF0DB37B2EFDB003D55A1AC177B5B0CC454DC95337B5790E3097F7D3E70BC6778D46A6FEE1B71EC57FEB762D6FD"
 decryptionKey="77271820C1AF1411A7A0BF19A6A37720F433A25FC2A700EA"
 validation="SHA1" />

ASP.NET 2.0 machineKey

<machineKey validationKey="BA5A2DC2E822B320B4177BADA578DCF3B6CB6E737D4FDC9BBBF7D016209FD5B21DC360A6754553CE26B39595E4D0915390008AF3DFE82A2D5CFED838ADC0025D"
 decryptionKey="8FD63025726B627F84736C14F066CAA32F994F5E065B2DBC13E163740CC37424"
 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();
}