ANNEX I
In Annex I to Implementing Decision (EU) 2021/1073, the following section 9 is added:
‘9. REVOCATION SOLUTION
9.1. DCC Revocation List (DRL) Provision
The Gateway shall provide endpoints and functionality to hold and manage the revocation lists:
9.2. Trust Model
All connections are established by the standard DCCG trust model by the NB TLS and NB UP certificates (see certificate governance). All information is packed and uploaded by CMS messages to ensure the integrity.
9.3. Batch Construction
9.3.1. Batch
Each revocation list shall contain one or multiple entries and shall be packed in batches which contain a set of hashes and their metadata. A batch is immutable and defines an expiration date which indicates when the batch can be deleted. The expiration date of all items in the batch must be exactly the same – meaning that batches must be grouped by expiry date and by signing DSC. Each batch shall contain a maximum of 1 000 entries. If the revocation list consists of more than 1 000 entries, multiple batches shall be created. Any entry may occur in at most one batch. The batch shall be packaged into a CMS structure and signed by the NB up certificate of the uploading country.
9.3.2. Batch Index
When a batch is created it shall be assigned a unique ID by the gateway and shall be automatically added to the index. The index of batches is ordered by the modified date, in ascending chronological order.
9.3.3. Gateway Behaviour
The gateway processes revocation batches without any changes: it can neither update nor remove, nor add any information to the batches. The batches are forwarded to all authorised countries (see chapter 9.6).
The gateway actively observes the expiration dates of batches and removes the expired batches. After the batch is deleted, the gateway returns an "HTTP 410 Gone" response for the deleted batch URL. Therefore, the batch appears in the batch index as "deleted".
9.4. Hash Types
The revocation list contains hashes that can represent different revocation types/attributes. These types or attributes shall be indicated in the provisioning of the revocation lists. The current types are:
Type
Attribute
Hash Calculation
SIGNATURE
DCC Signature
SHA256 of DCC Signature
UCI
UCI (Unique Certificate Identifier)
SHA256 of UCI
COUNTRYCODEUCI
Issuing Country Code + UCI
SHA256 of Issuing CountryCode + UCI
Just the first 128 bits of the hashes encoded as base64 strings are put into the batches and used to identify the revoked DCC
( 1 ) .
9.4.1. Hash type: SHA256(DCC Signature)
In this case the hash is calculated over the bytes of the COSE_SIGN1 signature from the CWT. For RSA signatures, the entire signature will be used as input. The formula for the EC-DSA signed certificates is using the r value as an input:
SHA256(r)
[required for all new implementations]
9.4.2. Hash type: SHA256(UCI)
In this case the hash is calculated over the UCI string encoded in UTF-8 and converted to a byte array.
[deprecated ( 2 ) , but supported for backwards compatibility]
9.4.3. Hash type: SHA256(Issuing CountryCode+UCI)
In this case CountryCode encoded as a UTF-8 string concatenated with the UCI encoded with a UTF-8 string. This is then converted to a byte array and used as input to the hash function.
[deprecated 2 , but supported for backwards compatibility]
9.5. API Structure
9.5.1. Revocation Entry Provisioning API
9.5.1.1. Purpose
The API delivers the revocation list entries in batches including a batch index.
9.5.1.2. Endpoints
9.5.1.2.1. Batch List Download Endpoint
The endpoints follow a simple design, returning a list of batches with a small wrapper providing metadata. The batches are sorted by date in ascending (chronological) order:
/revocation-list
Verb: GET
Content-Type: application/json
Response: JSON Array
{
‘more’: true|false,
‘batches’:
[{
‘batchId’: ‘{uuid}’,
‘country’: ‘XY’,
‘date’: ‘
2021-11-01T00:00:00Z’
‘deleted’: true | false
}, ..
]
}
Note : The result is limited by default to 1 000. If the flag ‘more’ is set to true, the response indicates that more batches are available for download. To download more items the client must set the If-Modified-Since header to a date no earlier than the last entry received.
The response contains a JSON array with the following structure:
Field
Definition
more
Boolean Flag which indicates that there are more batches.
batches
Array with the existing batches.
batchId
https://en.wikipedia.org/wiki/Universally_unique_identifier
country
Country Code ISO 3166
date
ISO 8601 Date UTC. Date when the batch was added or deleted.
deleted
boolean. True if deleted. When the deleted flag is set, the entry can be finally removed from the query results after 7 days.
9.5.1.2.1.1. Response Codes
Code
Description
200
All ok.
204
No content, if “If-Modified-Since” Header content has no match.
Request Header
Header
Mandatory
Description
If-Modified-Since
Yes
This header contains the last downloaded date to get just the newest results. On the initial call the header should be the set to the ‘2021-06-01T00:00:00Z’
9.5.1.2.2. Batch Download Endpoint
The batches contain a list of certificate identifiers:
/revocation-list/{batchId}
Verb: GET
Accepts: application/cms
Response:CMS with Content
{
‘country’: ‘XY’,
‘expires’: ‘
2022-11-01T00:00:00Z’,
‘kid’:’23S+33f=’,
‘hashType’:’SIGNATURE’,
‘entries’:[{
‘hash’:’e2e2e2e2e2e2e2e2’
}, ..]
}
The response contains a CMS including a signature which must match to the NB UP certificate of the country. All items in the JSON array contain the following structure:
Field
Mandatory
Type
Definition
expires
Yes
String
Date when the item can be removed.
ISO8601 Date/Time UTC
country
Yes
String
Country Code ISO 3166
hashType
Yes
String
Hash Type of the provided entries (see Hash Types)
entries
Yes
JSON Object Array
See Table Entries
kid
Yes
String
base64 encoded KID of the DSC used to sign the DCC.
If the KID is not known then the string `UNKNOWN_KID` (excluding the `) can be used.
Notes:
—
Batches shall be grouped by expiry date and DSC – all items shall expire at the same time and have been signed by the same key.
—
Expiry time is a date/time in UTC because EU-DCC is a global system and we must use an unambiguous time.
—
The expiry date of a permanently revoked DCC shall be set at the expiry date of the corresponding DSC used to sign the DCC or at the Expiration Time of the revoked DCC (in which case the used NumericDate/epoch times shall be treated as being in the UTC time zone).
—
National Backend (NB) shall remove items from their revocation list when the expiration date is reached.
—
NB may remove items from their revocation list in the case that the kid used to sign the DCC is revoked.
9.5.1.2.2.1. Entries
Field
Mandatory
Type
Definition
hash
Yes
String
First 128 bits of the SHA256 hash encoded as a base64 string
Note: The entries object contains currently just a hash, but to be compatible with changes in the future an object was chosen, instead of a json array.
9.5.1.2.2.2. Response Codes
Code
Description
200
All ok.
410
Batch gone. Batch can be deleted in the national backend.
9.5.1.2.2.3. Response Headers
Header
Description
ETag
Batch ID.
9.5.1.2.3. Batch Upload Endpoint
The upload is done over the same endpoint via POST Verb:
/revocation-list
Verb: POST
Accepts: application/cms
Request: CMS with Content
ContentType: application/cms
Content:
{
‘country’: ‘XY’,
‘expires’: ‘
2022-11-01T00:00:00Z’,
‘kid’:’23S+33f=’,
‘hashType’:’SIGNATURE’,
‘entries’:[{
‘hash’:’e2e2e2e2e2e2e2e2’
}, ..]
}
The batch shall be signed using the NB UP certificate. The Gateway shall verify that the signature was set by the NB UP for the given country . If the signature check fails then the upload shall fail.
NOTE : Every batch is immutable and can’t be changed after uploading. It can be deleted, though. The ID of every deleted batch is stored, and an upload of a new batch with the same ID is rejected.
9.5.1.2.4. Batch Delete Endpoint
A batch can be deleted over the same endpoint via DELETE Verb:
/revocation-list
Verb: DELETE
Accepts: application/cms
ContentType: application/cms
Request: CMS with Content
Content:
{
‘batchId’: ‘...’
}
or, for compatibility reasons, to the following endpoint with the POST verb:
/revocation-list/delete
Verb: POST
Accepts: application/cms
ContentType: application/cms
Request: CMS with Content
Content:
{
‘batchId’: ‘...’
}
9.6. API Protection/GDPR
This section specifies measures for the implementation to comply with the provisions of the Regulation 2021/953 as regards to the processing of personal data.
9.6.1. Existing Authentication
The Gateway currently uses the NB TLS certificate to authenticate the countries connecting to the Gateway. This authentication can be used to determine the identity of the country connected to Gateway. That identity can then be used to implement access control.
9.6.2. Access Control
To be able to lawfully process personal data the Gateway shall implement an access control mechanism.
The gateway implements an Access Control List combined with Role Based Security. In that scheme, two tables shall be maintained – one table describing which Roles can apply which Operations to which Resources, the other table describing which Roles are assigned to which Users.
To implement the controls required by this document, three Roles are required, and that is:
RevocationListReader
RevocationUploader
RevocationDeleter
The following endpoints shall check to see if the User has the Role RevocationListReader; if they do then access shall be granted, if they do not then an HTTP 403 Forbidden shall be returned:
GET/revocation-list/
GET/revocation-list/{batchId}
The following endpoints shall check to see if the User has the Role RevocationUploader; if they do then access shall be granted, if they do not then an HTTP 403 Forbidden shall be returned:
POST/revocation-list
The following endpoints shall check to see if the User has the Role RevocationDeleter; if they do then access shall be granted, if they do not then an HTTP 403 Forbidden shall be returned:
DELETE/revocation-list
POST/revocation-list/delete
The Gateway shall also provide a reliable method whereby the administrators can manage the Roles that are linked to the Users in such a way as to reduce the chance of human errors whilst also not burdening the functional administrators.’
( 1 ) Please also consider 9.5.1.2 for the detailed API descriptions.
( 2 ) Deprecated means that this feature shall not be considered for new implementations but shall be supported for existing implementations for a well-defined period of time.
