On 04/30/2014 10:19 AM, Petr Spacek wrote:
following text summarizes schema & DIT layout for DNSSEC key storage
This is subset of full PKCS#11 schema . It stores bare keys with
few metadata attributes when necessary.
The intention is to make transition to full PKCS#11-in-LDAP schema 
as easy as possible. This transition should happen in next minor
version of FreeIPA.
In theory, the transition should be just adding few object classes to
existing objects and populating few new metadata attributes. Related
object classes are marked below with "(in long-term)".
Please comment on it soon. We want to implement it ASAP :-)
- Private key is stored in LDAP as encrypted PKCS#8 blob
- Public key is published in LDAP
- Encrypted with symmetric "DNSSEC master key" (see below)
- Private key - represented as LDAP object with object classes:
ipaEPrivateKey  # encrypted data
ipaWrappedKey  # pointer to master key, outside scope of pure
ipk11PrivateKey  (in long-term) # PKCS#11 metadata
- Public key - represented as LDAP object with object classes:
ipaPublicKey  # public key data
ipk11PublicKey  (in long-term) # PKCS#11 metadata
- Stored in LDAP as encrypted blob
- Encrypted with asymmetric "replica key" (see below)
- 1 replica = 1 blob, n replicas = n blobs encrypted with different keys
- A replica uses it's own key for master key en/decryption
- Represented as LDAP object with object classes:
ipk11SecretKey  (in long-term)
- Private key is stored on replica's disk only
- Public key for all replicas is stored in LDAP
- Represented as LDAP object with object classes:
ipk11PublicKey  (in long-term)
DNSSEC key material
- Container: cn=keys, cn=sec, cn=dns, dc=example
- Private and public keys are stored as separate objects to
accommodate all PKCS#11 metadata.
- We need to decide about object naming:
- One obvious option for RDN is to use uniqueID but I don't like it.
It is hard to read for humans.
- Other option is to use uniqueID+PKCS#11 label or other attributes
to make it more readable. Can we use multi-valued RDN? If not, why?
What are technical reasons behind it?
I would encourage you not to use multi-valued RDNs. There aren't any
technical reasons - multi-valued RDNs are part of the LDAP standards and
all conforming LDAP implementations must support them. However, they
are hard to deal with - you _must_ have some sort of DN class/api on the
client side to handle them, and not all clients do - many clients expect
to be able to just do dnstr.lower() == dnstr2.lower() or possibly do
As far as being human readable - the whole goal is that humans _never_
have to look at a DN. If humans have to look at and understand a DN to
accomplish a task, then we have failed.
Has the DogTag team reviewed this proposal? Their data storage and
workflows are similar.
It is question if we like:
nsUniqID = 0b0b7e53-957d11e3-a51dc0e5-9a05ecda
nsUniqID = 8ae4190d-957a11e3-a51dc0e5-9a05ecda
DNSSEC key metadata
- Container (per-zone): cn=keys, idnsname=example.net, cn=dns
- Key metadata can be linked to key material via DN or ipk11Id.
- This allows key sharing between zones.
(DNSSEC-metadata will be specified later. That is not important for
Replica public keys
- Container: cn=DNS,cn=<replica
- or it's child object like cn=wrappingKey
- Container: cn=master, cn=keys, cn=sec, cn=dns, dc=example
- Single key = single object.
- We can use ipk11Label or ipk11Id for naming:
ipk11Label=dnssecMaster1, ipk11Label=dnssecMaster2, etc.
Read DNSSEC private key
1) read DNSSEC private key from LDAP
2) ipaWrappedKey objectClass is present - key is encrypted
3) read master key denoted by ipaWrappingKey attribute in DNSSEC key
4) use local replica key to decrypt master key
5) use decrypted master key to decrypt DNSSEC private key
Add DNSSEC private key
1) use local replica key to decrypt master key
2) encrypt DNSSEC private key with master key
3) add ipaWrappingKey attribute pointing to master key
4) store encrypted blob in a new LDAP object
Add a replica
1) generate a new replica-key pair for the new replica
2) store key pair to replica-file (don't scream yet :-)
4) add public key for the new replica to LDAP
3) fetch master key from LDAP
4) encrypt master key with new replica public key
5) store resulting master key blob to LDAP
6) generate a new replica-key pair (!)
7) store new public key to LDAP
8) remove old public key (from replica-file) from LDAP
9) fetch master key
10) decrypt master key using old private key (from replica-file)
11) encrypt master key using new private key (generated locally)
12) replace old master key blob in LDAP with new blob (from step 11)
Delete a replica
This is the tricky part. New master key has to be generated on some
other replica. What should we do if the ipa-replica-manage command was
run on deleted replica?
I propose to split replica master key roll-over to two phases:
Any machine in IPA domain (including to-be deleted replica):
1) Delete public key associated with replica from LDAP
2) Flip a bit in master key metadata and say "this key needs to be
(Maybe we can disable ipk11Wrap boolean to indicate that this key
should not be used for key wrapping.)
3) Periodically check that master key is obsolete
4) Wait for (random period of time) to limit probability of collision
5) Check that master key is really obsolete and new one is not present
6) Generate a new master key
7) Encrypt new master key with all replica-public-keys stored in LDAP
8) Store new master key blobs to a new LDAP object
(Conflicts are not a problem up to now because we are not
deleting old key. In worst case, we will have multiple new master keys.)
*What should we do now?*
9) ??? Re-encrypt all DNSSEC keys with a new master key? (What if we
have write conflict now?)
??? Let old keys there and wait until key rotation mechanism
replaces all old DNSSEC keys with new DNSSEC keys encrypted with a new
master key (~ one year)?
10) Old master key can be deleted when no other object is referencing
Congratulations to people who reached this line and didn't skip
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