Audit Letter Validation (ALV)
The CCADB uses an Audit Letter Validation (ALV) tool that is provided by Microsoft to automatically parse and validate audit statements. The ALV eliminates manual processing, but it requires audit statements to follow some basic rules in order to function properly. If an audit statement fails to meet any of the Audit Statement Requirements and Format Rules, the CA will be asked to work with their auditor to provide an audit statement that passes ALV.
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CAs are required to update the audit, CP, CPS and test website information for their certificate hierarchies at least annually. To provide this information for root certificates, create one Audit Case in the CCADB for a particular set of audits (e.g. Standard Audit, BR audit, EV SSL Audit, Code Signing Audit).
Subordinate CAs who operate non-technically-constrained intermediate certificates have the keys to the internet just as much as the CAs who have root certificates directly included in a browser root store. Meaning that such subordinate CAs can also issue TLS certificates for any website or domain, so it is imperative that the same rules are being followed by all subordinate CAs operating non-technically-constrained intermediate certificates. There are currently about 150 root certificates in browser root stores, which leads to about 3,000 intermediate certificates that are trusted by browser root stores.
To help enforce the rules at the intermediate certificate level, CCADB participants require disclosure of intermediate certificates. CCADB automatically runs ALV on the intermediate certificate records and reports the results to CAs and root store operators in their CCADB home pages.
CAs are required to annually update the audit and CP/CPS for their non-technically-constrained intermediate certificates chaining to root certificates included in browser root stores. To provide this information for intermediate certificates, directly update the corresponding record in the CCADB then click on the “Audit Letter Validation [ALV]” button.
When the audit statements for an intermediate certificate are the same as the certificate that signed it, check the “Audits Same as Parent” checkbox instead of providing separate audit information. When the “Audits Same as Parent” field is checked for an intermediate certificate record, the CCADB will look up the parent chain until audit statements are found, and then run ALV using those audit statements. When the “Audits Same as Parent” field is not checked, the CCADB will directly pass the audit statements in the intermediate certificate record into ALV.
The following fields are set by running ALV on an intermediate certificate record in the CCADB. CAs may cause ALV to be run on the record by clicking on the “Audit Letter Validation [ALV]” button. Additionally CCADB has automated processes that will regularly check for intermediate certificate records that need to have ALV run.
- Standard Audit ALV Found Cert
- This field will be set to PASS when ALV finds the SHA-256 Fingerprint for that certificate in the standard audit statement
- BR Audit ALV Found Cert
- This field will only be set when the Derived Trust Bits field has “Server Authentication” in its list.
- This field will be set to PASS when ALV finds the SHA-256 Fingerprint for that certificate in the BR audit statement.
- EV SSL Audit ALV Found Cert
When ALV returns FAIL for “Standard Audit ALV Found Cert”, “Code Signing Audit ALV Found Cert”, “BR Audit ALV Found Cert”, or “EV SSL Audit ALV Found Cert” for one of your CA’s intermediate certificate records in the CCADB, do the following.
- Check the corresponding audit statement to make sure the SHA-256 fingerprint of the certificate is correctly listed.
- If the SHA-256 fingerprint is listed in the audit statement, then make sure that it meets the format specifications, such as no colons, no spaces, no line feeds.
- Have your auditor provide an updated audit statement that follows the formatting requirements for the SHA-256 Fingerprints.
- If you do not agree with the ALV results, add comments to the “Standard Audit ALV Comments”, “Code Signing Audit ALV Comments”, “BR Audit ALV Comments”, or “EV SSL Audit ALV Comments” fields to indicate that the SHA-256 fingerprint is listed correctly in the audit statement.
- If the audit statement is indeed missing the SHA-256 fingerprint for the certificate, then file an Incident Report, and add the link to the Incident Report to one of the “…ALV Comments” fields.
- If the CA has a currently valid audit report at the time of creation of the intermediate certificate, then the current audit statement does not need to be updated and the new certificate must appear on the CA’s next periodic audit reports.
- Intermediate certificates that contain “Server Authentication” in the Derived Trust Bits field are considered to be technically capable of issuing TLS certificates, and they must be listed in the CA’s BR audit report.
- If multiple intermediate certificates with the same Subject + SPKI have been issued, each one must have their SHA-256 Fingerprint listed in appropriate audit statements according to the Derived Trust Bits field.
- Cross-Certificates are also considered intermediate certificates, which must also be audited and specifically listed in the applicable audit statements according to the Derived Trust Bits field.
- Self-signed certificates that share a Subject and SPKI with a root certificate that is included in a root store are treated by browsers as intermediate certificates because they chain up to an included root, so these certificates must also be listed in the applicable audit statements according to the Derived Trust Bits field.
- An example of this situation is when an older version of a root certificate exists and a newer version of the root certificate is created. In this case, a valid chain may be constructed as: leaf –> untrusted root –> trusted root. In other words, that “untrusted” root is technically trusted by the root store because it chains to a trusted root, so it’s SHA256 fingerprint must also be listed in the applicable audit statements.
- Have your auditor issue a revised report that includes the intermediate certificate.
- If the certificate has been in existence for past audit periods, then you must also file an Incident Report.
- An Incident Report may not be needed if the certificate is self-signed and has the same Subject and SPKI as other certificates listed in the audit statement. For example, this can happen when a root store includes one version of a root certificate, but another version of the root certificate can be part of a valid chain constructed as: leaf –> untrusted root –> trusted root.
- Revoke the intermediate certificate in accordance with root store policies and the BRs.
- If your CA decides not to revoke the certificate within the timeline specified by section 4.9 of the BRs, then that is another incident, which must be addressed in a separate Incident Report.
Common ALV Findings
ALV formatting requirements are specified in section 5.1 of the CCADB Policy.
|ALV Error||Meaning||Recommended Action|
|Thumbprint not found||SHA-256 Fingerprint of the certificate not found in the audit statement.||
|Statement Date Not Found||The audit statement date was not found in the audit statement.||
|Audit Period Not Found||ALV was unable to find the audit period start and end dates in the audit statement.||
|Failed to validate EKU ... because the standard names and standard policies are not found in the audit letters||ALV was unable to find the specific text (case insensitive) that it looks for for each EKU. For example, "319 411-1 v1.1.1, dvcp;ovcp;ptc-br"||Make sure that the audit statement correctly indicates the audit criteria that was used, and that it satisfies root store requirements.
The following are xamples of the policy information that ALV looks for, depending on the EKU's or Trust Bits that each root store has applied to the root certifiate, and the "Derived Trust Bits" for an intermediate certificate.
|Auditor Not Found||ALV was unable to find the specified auditor name in the audit statement||
|CA Owner Not Found||ALV was unable to find the CA Owner's name (as specified in the CCADB) in the audit statement. For intermediate certificate records with their own audit statements this will be the value in the "Subordinate CA Owner" field||
|Download Audit Letter Fail||The provided link to the audit statement did not work.||Correct and test the audit statement links in the CCADB record then try again.|
|Audit Letter Not Found In Certain Location||ALV contains a list of known audit locations, such as auditor websites and cpacanada.ca. This error will be given when the URL to the audit statement does not match any of the URLs in the known audit locations.||
|Audit Letter Not PDF||ALV was unable to download and parse the document at the audit statement URL.||Update the Audit Statement links in the record to point to a valid PDF file.|