Bad Key Exception using RSACryptoServiceProvider
<p>The key exchange method is: RSA-PKCS1-KeyEx</p>

<p>So I don't think the answers in other similar questions apply and I have no control over the certificate - it's valid and is supposed to work.  </p>

<p>.NET Framework 3.5</p>

<p>The code:</p>

<pre><code>        RSACryptoServiceProvider rsa = (RSACryptoServiceProvider)cert.PublicKey.Key;
        byte[] bytestodecrypt = Convert.FromBase64String(SignatureValue);
        byte[] plainbytes = rsa.Decrypt(bytestodecrypt, false); 
</code></pre>

<p>Screenshot of the attributes of the rsa object:</p>

<p><a href="https://i.stack.imgur.com/iRWFd.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iRWFd.png" alt="enter image description here"></a></p>