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Re: legal question about certs
I strongly support the idea that all certificates should be self-signed. But I
would like to make an additional point.
> However, there is a theory that for each transfer of rights in one direction,
> there is a transfer of responsibility in the other direction.
This is a key point. When you sign someone's certificate giving them rights or
describing them in some way then there must also be a contract, however informal,
that the person/group/entity in possesion of the matching private key will take
reasonable steps to protect the private key and will notify you if they believe
that the private key has been compromised. When you sign their certificate it
means, among other things, that you believe there is such a contract.
It is important that standards describing certificates make this very clear.
To sign a certificate when you don't have such a contract must be clearly
identified as a priori evidence of a preliminary to fraud.
This makes self-signing legally unnecessary. Still a good idea though. It is
much better to make bad things impossible rather than just illegal.
There is a point worth making about key compromise. For signing keys it doesn't
matter if the private key is completely lost: disk crash or smart card physically
wrecked. All certifcates for the public key are still valid - at worst harmless
and perhaps still valuable. Everything signed with that public key is still
valid. All that happens is that you have to get a new key pair and new certificates
to allow future signing.
This is quite different to the situation with encryption public keys where you
want to destroy or revoke the certificates that exist to stop people sending
you encrypted stuff that you can no longer decrypt. This is one of several
reasons why it is important to keep signing/authentication keys separate from
encryption keys. Revocation is a much simpler matter for signing keys.