ods-kasp - Man Page

OpenDNSSEC kasp specification

Description

The kasp file describes the parameters of the DNSSEC Key and Signing Policy (KASP), the policy used to sign zones. Each policy comprises a series of parameters that define the way the zone is signed.

KASP Parameters

A policy has a set of common parameters to identify the policy.

Policy Name

The name is used to link a policy to a zone that needs to be signed. Each policy must have a unique name. The policy named "default" is special, as it is associated with all zones that do not have a policy explicitly associated with them.

Policy Description

A policy can have a description associated with it.

Signatures Parameters

This section lists the parameters for the signatures created using the policy.

Signature Resign Interval

This is the interval between runs of the signer. For example, a zone that has a Re-sign Interval of PT2H (2 hours) is handled by the signer every 2 hours.

Signature Refresh Interval

The Refresh Interval is describing when a signature should be refreshed. As signatures are typically valid for much longer than the interval between runs of the signer, there is no need to regenerate the signatures each time the signer is running. This means that the Re-sign Interval must be smaller than the Refresh Interval. In order to make refreshing signatures possible, the Re-sign Interval should be at least half of the Refresh Interval. In the case a signer runs and detects that there is no change to the data being signed, signatures may be refreshed. A signature will be refreshed when the time until the signature expiration is closer than the Refresh Interval.

Signature Validity

The Signature Validity describes how long the signatures are valid for. This parameter groups two elements of information. The Default Signature Validity is the validity interval for all RRSIG records except those related to NSEC or NSEC3 records. For these records, the validity period is given by the value of the Denial Signature Validity.

Signature Jitter

The Signature Jitter (j) is the value added to or subtracted from the expiration time of signatures to ensure that not all signatures expire at the same time. The actual value of the jitter is a random value, uniformly ranging between Minus Signature Jitter and Signature Jitter [-j...j]. This value is added to Signature Validity to determine the signature expiration time.

Signature Inception Offset

This is a duration subtracted from the time at which a record is signed to give the inception time of the RRSIG record. This is required to allow for clock skew between the signing system and the system on which the signature is checked. Without it, the possibility exists that the checking system could retrieve a signature whose start time is later than the current time. The relationship between these elements is shown below in Figure 1.

Inception Signing Expiration
time time time
| | | | |
|---------------------|---------------------------|.......|.......|
| | | | |
[ +/- Jitter ]

| Inception offset | |
|<------------------->| Validity Interval |
| |<--------------------------------->|

Inception Signing reuse reuse new Expiration
time time signature time
| | | | | |
|---------------------|-----------------------------------|
| | | | | |
<-----> <-----> <----->
Re-sign Interval

|Refresh Interval|
|<-------------->|
| |

Figure 1: Signature Timing Parameters

Authenticated Denial of Existence Parameters

Authenticated denial of existence - proving that domain names do not exist in the zone - is discussed in this section. Below, the list of the parameters is given for creating NSEC or NSEC3 records using the policy.

NSEC or NSEC3

If the NSEC scheme is used to implement authenticated denial of existence, there are no record elements we can tune. If NSEC3 [RFC5155] is used, there are some more options.

NSEC3 Opt-Out

Whether to enable or disable "opt-out". This is an optimisation that means that NSEC3 records are only created for authoritative data or for secure delegations; insecure delegations have no NSEC3 records. For zones where a majority of the entries are delegations that are not signed - typically TLDs during the take-up phase of DNSSEC - this reduces the number of DNSSEC records in the zone.

NSEC3 Re-salt Interval

The is the interval between generating new salt values for the hashing algorithm.

NSEC3 Hash Parameters

The NSEC3 Hash Parameters tells parameters related to NSEC3.

NSEC3 Hash Algorithm

The NSEC3 Hash Algorithm tells what hashing algorithm should be used to create the NSEC3 records.

NSEC3 Hash Iterations

The NSEC3 Hash Iterations shows how many iterations of the hash function should be performed over the original owner name.

NSEC3 Hash Salt Length

The NSEC3 Hash Salt Length provides the length of the salt value to be generated.

Key Parameters

This section covers parameters related to keys. There are a number of parameters relating to both zone-signing keys (ZSK) and key-signing keys (KSK).

DNSKEY TTL

This is the time-to-live value for the DNSKEY resource records.

Key Retire Safety

The Key Retire Safety is the retire safety margin for the keys. This interval is a safety margin added to calculated timing values to ensure that keys are retired without there being a chance of signatures created with the keys being considered invalid.

Key Publish Safety

The Key Publish is the publish safety margins for the keys. This interval is the safety margin added to calculated timing values to ensure that keys are published and without there being a chance of signatures created with the keys being considered invalid.

Key Sharing

If multiple zones are associated with a policy, a key may be shared between zones. For example, if you have 100 zones then you will only use one set of keys instead of 100 sets. This will safe space in your HSM.

Key Purging Interval

Key Purging is the event where keys marked as dead (as defined by draft-ietf-dnsop-dnssec- key-timing [key-timing]) will be automatically purged from the key database. The Key Purging Interval is the interval of when Key Purging is done.

KSK Parameters

There are parameters specific for the KSK.

KSK Algorithm

The KSK Algorithm determines the algorithm used for KSKs.

KSK Lifetime

The KSK Lifetime determines how long the KSK is used for before it is must be rolled.

KSK Repository

The KSK Repository determines the location of the KSKs.

Manual KSK Rollover

It may be desirable to force that a key rollover will only be initiated on the command by the operator. Note that if KSK rollover is done automatically, there is currently still a step for the KSK that needs manual intervention, where the corresponding DS record for the key needs to be published to the parent before the rollover is completed.

ZSK Parameters

The same parameters for the KSK are available for the ZSK. The split between the series of parameters is that with a ZSK/KSK Split Signing Scheme, the values for the parameters may be different.

ZSK Algorithm

The ZSK Algorithm determines the algorithm used for ZSKs.

ZSK Lifetime

The ZSK Lifetime determines how long the ZSK is used for before it is must be rolled.

ZSK Repository

The ZSK Repository determines the location of the ZSKs.

Manual ZSK Rollover

The ZSK rollover will be fully automatic if Manual ZSK Rollover is disabled.

Zone Parameters

General information concerning the zones is described here.

Propagation Delay

The Propagation Delay is the amount of time needed for information changes at the master server for the zone to work its way through to all the secondary nameservers.

SOA Parameters

These parameters are necessary for maintaining the SOA record in the signed zone. These values will override values set for the SOA record in the input zone.

SOA TTL

This is the time-to-live of the SOA record.

SOA MINIUM

This is value for the MINIMUM RDATA element in the SOA record.

SOA Serial

This represents the format of the serial number in the signed zone. This is one of the following:
counter: Use an increasing counter (but use the serial from the unsigned zone
if possible).

datecounter: Use increasing counter in YYYYMMDDxx format (xx is the number of
increments within each day, starting at 00).

unixtime: The serial number is set to the "Unix time" (seconds since 00:00 on
1 January 1970 (UTC)) at which the signer is run.

keep: Keep the serial from the unsigned zone (do not re-sign unless it has been
incremented). This way, no signed zone is created unless the zone operator
explicitly initiated a zone update.

Parent Zone Parameters

If a DNSSEC zone is in a chain of trust, digest information about the KSKs used in the zone will be stored in DS records in the parent zone. To properly roll keys, timing information about the parent zone must be configured.

Propagation Delay

The Propagation Delay parameter related to the parent zone is the interval between the time a new KSK is published in the zone and the time that the DS record appears in the parent zone. In reality, this is a variable value. The value for the Propagation Delay in the policy should be a estimate.

DS TTL

This represents the DS time-to-live. The DS TTL should be set to the TTL of the DS record in the parent zone.

SOA Parameters

The SOA Parameters related to the parent zone gives information about the parent's SOA record. These are necessary to calculate the timings in particular rollover scenarios.

SOA TTL