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="E2B1E4C5CD3E85290EC353A9724B90DB092B00178BECA09D5BC281C145BE7716B5BEDA4B2D06D00183E792DF23B5B8E867CC77EE2AB722EAFCB3D6A2CFB24062"
 decryptionKey="C3292D6B0A2660A46387FF8B724DE2467F2BD5A443AF2E5C"
 validation="SHA1" />

ASP.NET 2.0 machineKey

<machineKey validationKey="F84CC2204212ED8572A6A58C66B99D4F9F63B6738A7E82B7378D65093A87711E581A79E969D0DFDD034CDA6A312C83790E03E74AC9588A60BF715424D62ECCA0"
 decryptionKey="601E800B557BEFE193BC6A9B9A2CFC3E39C8DE3CD80CC5B51B8721C5A5C47435"
 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();
}