We had some fun requesting key for accessing nist time servers. the process is (quoted from website)

NIST currently offers this service free of charge. We require written requests to arrive by U.S. mail or fax containing:

Your organization’s name, physical address, fax number (if desired as a reply method).

One or more point-of-contact personnel or system operators authorized to receive key data and other correspondence: names, phone numbers, email addresses. Up to four static IPv4 network addresses under the user’s control which will be allowed to use the unique key. By special arrangement, additional addresses or address ranges may be requested.

Desired hash function (“key type”). NIST currently supports MD5, SHA1, SHA256, and HMAC-SHA256. Please list any limitations your client software places on key values, if known: maximum length, characters used, or whether hexadecimal key representations are required. If you prefer, please share details about your client software or NTP appliance so we can anticipate key format issues. Desired method for NIST’s reply: U.S. mail, fax, or a secure download service operated by Department of Commerce.

NIST will not use email for sending key data.

ps. there actually seems to be improvement over what they had year ago. they added "secure download service". and previously they had message that nobody assigned to actively monitor mailbox so if you didn't get key, please email us so we will check it