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I'm concerned about the key-removal functionality. The website (https://keys.tdjs.tech https://keys.tdjs.tech) reads: "Enter a message clearsigned with the key

by fwip 7y ago

I'm concerned about the key-removal functionality. The website (https://keys.tdjs.tech https://keys.tdjs.tech) reads: "Enter a message clearsigned with the key you wish to remove (message content is not important)" My understanding of this is that anyone with a copy of anything you've ever signed can revoke your key. I hope I'm misunderstanding.

Deadsunrise 7y ago
The message has to be signed with the private key of the key so no one but the real owner can delete it. In fact, in the readme: > If a user can prove that a key belongs to them (by signing a message with their private key) then they are able to remove their public key with no interaction needed from the server operator. Once a key is removed, it is removed from all servers in the pool. This is a pretty fucking awesome idea.
- daxelrod 7y ago
  The attack that I believe fwip is concerned about is: Alice sends an email to Bob and clearsigns the message. Bob, or anyone else who intercepts the email is now able to paste that message into the form and remove Alice's key from the keyserver. This could be mitigated by requiring it to be a specific message.
- sp332 7y ago
  To prove that you have the private key, they should send you a challenge message and make you send back that message with a signature. If you can send any signed message, anyone who has ever received a signed message from a person can upload it and revoke that person's key.
  - progval 7y ago
    > If you can send any signed message Reading the code, it does indeed allow any signed message: https://github.com/tdjsnelling/dat-keyserver/blob/12fa3e8389a6f90d312e1e664006df4d8391ecd5/index.js#L288-L369 https://github.com/tdjsnelling/dat-keyserver/blob/12fa3e8389...
- edwintorok 7y ago
  GnuPG generates a revocation certificate when you're creating a new key, import that and it requires no interaction from you or the keyserver operator. And it works even if you've forgotten the passphrase of your GPG key. Obviously you don't want to put that file anywhere public, and if it gets compromised you can just publish the file to the keyservers yourself and generate a new key.
tdjsnelling 7y ago
That is something glaringly obvious that I should have considered, thanks for pointing it out. I'll make the change to require a specific message.
- a1369209993 7y ago
  Probably glaringly obvious (but in this case also), but you should make sure that the specific message starts with something highly conspicuous like "DAT KEYSERVER KEY REVOCATION REQUEST ID#<token>" to avoid social engineering someone with "Hey can you sign this token so I know you're you?".

by fwip 7y ago

Deadsunrise 7y ago

The message has to be signed with the private key of the key so no one but the real owner can delete it. In fact, in the readme: > If a user can prove that a key belongs to them (by signing a message with their private key) then they are able to remove their public key with no interaction needed from the server operator. Once a key is removed, it is removed from all servers in the pool. This is a pretty fucking awesome idea.

daxelrod 7y ago
The attack that I believe fwip is concerned about is: Alice sends an email to Bob and clearsigns the message. Bob, or anyone else who intercepts the email is now able to paste that message into the form and remove Alice's key from the keyserver. This could be mitigated by requiring it to be a specific message.
sp332 7y ago
To prove that you have the private key, they should send you a challenge message and make you send back that message with a signature. If you can send any signed message, anyone who has ever received a signed message from a person can upload it and revoke that person's key.
- progval 7y ago
  > If you can send any signed message Reading the code, it does indeed allow any signed message: https://github.com/tdjsnelling/dat-keyserver/blob/12fa3e8389a6f90d312e1e664006df4d8391ecd5/index.js#L288-L369 https://github.com/tdjsnelling/dat-keyserver/blob/12fa3e8389...
edwintorok 7y ago
GnuPG generates a revocation certificate when you're creating a new key, import that and it requires no interaction from you or the keyserver operator. And it works even if you've forgotten the passphrase of your GPG key. Obviously you don't want to put that file anywhere public, and if it gets compromised you can just publish the file to the keyservers yourself and generate a new key.

tdjsnelling 7y ago

That is something glaringly obvious that I should have considered, thanks for pointing it out. I'll make the change to require a specific message.

a1369209993 7y ago
Probably glaringly obvious (but in this case also), but you should make sure that the specific message starts with something highly conspicuous like "DAT KEYSERVER KEY REVOCATION REQUEST ID#<token>" to avoid social engineering someone with "Hey can you sign this token so I know you're you?".