diff --git a/handbook/computing/keyexchange.html b/handbook/computing/keyexchange.html
index dc9216799..4234cfe72 100644
--- a/handbook/computing/keyexchange.html
+++ b/handbook/computing/keyexchange.html
@@ -34,6 +34,8 @@ automatic - no passwords needed.</p>
 
 <p>A public key file looks like this: <code>ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEApc9+PAMrDtWa8D8/Z<em>..lots more like this..</em>qmkW/cQ== wookey@kh</code>i.e. a long string of characters with 'ssh-rsa' at the start and an ID at the end (often 'user'@'machine').</p>
 
+<p>UPDATE: security and keys rapidly get out of date. READ this <a href="https://www.brandonchecketts.com/archives/ssh-ed25519-key-best-practices-for-2025">ssh-ed25519-key-best-practices-for-2025</a> and follow its advice. It is more up to date than the text on this page.
+
 <h3>Windows</h3>
 <p>On Windows 10 or later openssh comes built-in. Open a command terminal and run <tt>ssh</tt> to see if you have it installed. If so just follow the linux instructions on this page - the process is identical. You can install it if it's not there. <a href="https://learn.microsoft.com/en-us/windows-server/administration/openssh/openssh_install_firstuse">(Microsoft setup instructions)</a>.
 </p>