SCMS CV Pilots Documentation : RA - Download Local Certificate Chain File

EEs use this service to download a local certificate chain file.

PORT	8892
PATH	/download/local-certificate-chain
HTTP Method	GET
HTTP Request Body	Empty
HTTP Request Headers	Optionally, the request may include the standard HTTP Header 'If-None-Match' containing the file name of the local certificate chains file that the EE currently possesses, excluding any path. For example: If-None-Match: "local_certificate_chains_01_03.oer" This is used to prevent the same file from being downloaded by the device multiple times.
HTTP Response Body	File containing the local certificate chains represented by an OER encoded ASN.1 serialized ScopedLocalCertificateChainFile. The file name returned is of the form: local_certificate_chains_<X>_<Y>.<Z> Where: X is the global certificate chain version, i.e., the cert_chain_file_id parameter found in the Global Policy File Y is the local certificate chain version Z is one of the permitted encoding formats (oer) from the file name in the request message OR An HTTP code of 304 (Not Modified), if the provided file name in the 'If-None-Match' header matches the current version available on the RA server.

Preconditions

None

Postconditions

Returned file contains SCMS certificates chains that the device will use

Error Handling

See "RA-EE Errors" in Overview of Used Error Codes

Quality of Service

Estimated values are per logical unit, meaning multiple individual nodes can contribute to achieve the desired level of service. The number of vehicles that potentially invoke this service in a week is a function of the number of years in service:

Formula for estimated quality of service as a function of year

Quality Metric

Rationale

1 Year

3 Years

5 Years

10 Years

Throughput

Assuming half of all new cars plus all existing vehicles need to download local certificate chain file in the same week.

8,500,000 new vehicles / 604,800 seconds/week

= 14 requests / second

(8,500,000 new vehicles + 34,000,000 existing vehicles) / 604,800 seconds/week

= 70 requests / second

(8,500,000 new vehicles + 68,000,000 existing vehicles) / 604,800 seconds/week

= 126 requests / second

(8,500,000 new vehicles + 153,000,000 existing vehicles) / 604,800 seconds/week

= 267 requests / second

Quality of Protection

RA protects access with HTTPS (TLS V1.2)
Supports at a minimum OpenSSL cipher suite ECDHE-ECDSA-AES128-SHA256