eMudhra, an Indian company that sells digital certificates under the emSign brand, has revoked eight more intermediate certificate authority certificates after finding that private keys were handled improperly when they were generated. The number of affected intermediate certificates is now 16.
Both sets trace back to a custom Python script that eMudhra used in April 2025 to move private keys between hardware security modules. The company wrote the script after delays in getting new hardware.
Two sets of keys
The first eight keys, which use the ECDSA algorithm, were cut down to a single byte by a bug in the script, so anyone could recover them almost at once. A security researcher showed on 17 October that they could be found by testing only 256 values, and eMudhra revoked those certificates the next day.
The second eight keys use RSA. They were not weakened, but the script handled them in the memory of the host computer instead of keeping them inside the protected module, and eMudhra could not show that this met its own certification practice rules. Those certificates were revoked on 7 November. The second set covers 195 issued certificates, according to a technical report: 130 for domain-validated TLS, 63 for organisation-validated TLS and two for code signing. Some were issued from May 2026, the last on 3 November. eMudhra says the affected customer certificates have been replaced or migrated.
Missed warnings and next steps
In June 2025 eMudhra found certificate revocation lists signed with keys that did not match their certificates. It fixed the signing but did not look into why, a gap the reports describe as an early warning. On 19 October it told a browser forum that the RSA authorities were not affected, and it changed that view in early November after talks with browser root programs.
eMudhra has said it will exit the publicly trusted TLS certificate business and move remaining customers to another provider. It plans to stop issuing under its remaining first-generation hierarchy by 16 November. An independent review by KPMG is due by 4 December. The company says it has found no evidence that the compromised keys were used maliciously.
Vendor action
Mozilla, Google and Apple released protections against the compromised certificates, and Microsoft issued out-of-band updates on 26 October. Microsoft begins removing ten eMudhra roots on 16 November, and Apple ends trust in all first-generation certificates on 30 November. A researcher's disclosure site says anyone who held an October key could have impersonated any website; browsers that enforce certificate transparency would not have been fooled. The reports do not say how many users in India are affected.
