Are there any actual disadvantages to a key signing party?

Question

At the beginning of the year staff are required to attend a key signing party - after changing their keys. They are required to bring said keys on USB sticks, at the end of the party each member of staff should have a copy of each others key. There is a workstation available at the end too.

See, for me I can't see any disadvantages that couldn't be easily amended, such as forgetting their key, or forgetting to create a fresh key, they could both be easily solved within half an hour. Is there any reason to amend this? Is there a more secure/easier way to pass around public keys to one another?

Answer 1

Key Signing Party is not just about random character generation and computers. It's about the chain of trust you create/strengthen by showing your key with a document of yours(and that is valid inside your country, of course).

The question here is: The person KNOWS that will have a key signing party and it does not bring a key or forget to generate one? That is something to worry about, cause there is a level of stupidity that is very high on this person, or he is not aware(even doesn't care) about the event.

Second. The "no computer" rule is another item inside the chain of trust that this kind of event creates: Key signing parties themselves generally do not involve computers, since that would give adversaries increased opportunities for subterfuge. And usb sticks can be easily replaced by attackers the same way a notebook could be turned on with the "hey bro, lemme generate another key cause i forgot mine" breaking the trust.

So, your company is already playing wrong by using massive external storage to exchange keys on a workstation. Unless everyone is looking at the monitor while the fingerprints are transcript to a text file/word document/whatever one by one, i would not TRUST on the members of this party.

tl,dr: If this party will be done with USB sticks, it's better that everyone give the keys fingerprint to your HR(or other management staff trusted by your company board members), and then, they distribute those fingerprints to your team. There are no disvantages on key signing parties, unless there is a computer involved(or document forgery, but that is a matter for parties where nobody knows each other, what is pretty difficult).

Answer 2

A key signing party like that sounds very inefficient, because for n employees it seems to require n^2 interactions. Note that this is precisely one of the problems that public key cryptography is supposed to solve!

The alternative would be to designate some small set of people as the key management team, responsible for key collection, certification and distribution. They'd be acting exactly like a certificate authority, but likely in a more informal fashion. Their job would be this:

1. The key management team needs to establish procedures for:
   • Proving to any other employee that they are legitimate members of the key management team;
   • Proving whether a person who says they are employee X really are who they claim.
2. The key management team uses these procedures to securely:
   • Give their own public signature verification keys to all other employees, without anybody being able to impersonate the key management team.
   • Collect every employee's public keys, and certify each of them by signing it with their own, without any employee or external party being able to impersonate an employee.
3. Publish the directory of certified keys.

Employees now also have the responsibility of:

1. Whenever somebody approaches them claiming they are a member of the key management team, verifying that they are not an impersonator.
2. Before they trust anybody's public key, checking that it has been signed by the key management team.

Answer 3

Typically, during key signing party you share fingerprints, and perform key singing at a later time after verifying fingerprints. Using this scheme, keys are supposed to be very long lived, so people often memorize their own fingerprints and can write them down from memory. As such, changing keys yearly is counter-productive as it leads to more human errors.

When sharing fingerprints, USB drives (or any other digital storage) are unnecessary. In this specific case, USB drives offer a potential attack vector that could result in one malicious/infected user spreading payload to the entire group. This is one of the reasons "No Computers" rule is practiced and enforced with traditional key singing parties.

In my view, key signing parties are antiquated. Set up PKI system with your own CA that your organization maintains and controls. You don't actually need to pay or trust any outside CAs to get such setup going.