An Authorization Code (also called an Auth Code or EPP Key) is required when transferring domains from one registrar to another. The transfer Authorization Code is created when the domain is first registered and can be obtained from the current Registrar for your domain. If you have a .DE domain name, an Authorization Code is only valid for 30 days once it’s created or changed.
Additionally, your Domain Provider can email the transfer Authorization Code (as well as the domain’s username and password) to the Administrative Contact email address on file. You can see the current Administrative Contact email address for the domain by performing a WHOIS lookup.