Sectigo: Use of forbidden subjectPublicKeyInfo algorithm

Sectigo faced issues with the issuance of certificates containing the forbidden P-521 public key algorithm. The problem was identified through discussions in the Mozilla security policy forum. Sectigo responded by implementing a code change to prevent further issuance of such certificates. However, it was later revealed that the code change only addressed one of two pathways for certificate issuance, allowing some certificates with P-521 keys to be issued. Sectigo has since taken steps to ensure compliance with Mozilla's policies and has committed to improving their QA processes.

1. 2019-01-08 Initial report of P-521 key usage
2. 2019-01-09 Code change implemented to stop issuing P-521 certificates
3. 2019-07-22 Further code change implemented to close off remaining issuance pathway