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="5494C7E065E9811D2F7377A30452C43421D16FF8303A34CDC5491BC3C122AD64E4CDD522F8A464CDA50829A890BAB57C783D6E4C6C30CD7601CA5BCB1B505534"
 decryptionKey="DE7897D9C1C30B5FD1CEDE02C55A8BAD5C113E12BED09A51"
 validation="SHA1" />

ASP.NET 2.0 machineKey

<machineKey validationKey="02892588CD5B689D97DB9E40551388136DBCFDE3DFB57343BFE110F9983401540A73BE715DF2A0F8F3EA5CFF3AE730DA36D5D41E3400A0E24E582A32705DBBE3"
 decryptionKey="4C065140ECC4B0F6CBC0C5E964B0344CEC08B79B59A38C945A290BF31EC10E40"
 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();
}