eMudhra Revokes Additional Certificate Authorities Following Critical Python Script Failure
A faulty custom script caused severe cryptographic vulnerabilities, forcing the revocation of eight more CAs.
1Script Failure Triggers Revocations
eMudhra has revoked eight additional intermediate certificate authorities following a critical failure in a custom Python script used during an April 30, 2025, key ceremony. While the company previously claimed these specific RSA keys were unaffected, internal assessments confirmed the script mishandled key material, violating established security protocols for hardware security modules.
2The Origin of the Flaw
The issues stem from a custom script designed to wrap and unwrap keys for transport between Utimaco and Crypto4A hardware security modules. During this process, the script read private keys into the ceremony computer's memory. For eight ECDSA keys, a single line of code truncated the private values to just one byte.
3Insecure Keys Remained Active
The truncated keys were so weak that some consisted of values as small as four. Despite this extreme vulnerability, the keys produced valid signatures that passed two WebTrust audit cycles unnoticed. The company failed to implement tests to verify key strength or compare the certified keys against the original generated versions.
4Compliance and Security Failures
The eight RSA keys were revoked because eMudhra cannot demonstrate compliance with its own Certification Practice Statement regarding secure key handling. Because the private exponents and primes were exposed in the ceremony computer's memory, the company lacks reliable logs to prove the keys were handled according to mandatory security standards.
5Scope of the Impact
The affected certificates include 195 total issuances, covering 29 of the company's own domains, various universities, and government entities. Of these, 130 originated from the EM DV TLS CA - G2C, 63 from the EM OV TLS CA - G2C, and two from the code-signing CA. All holders have been migrated to new certificates.
6Early Warning Signs Ignored
Invalid Certificate Revocation List signatures detected in June 2025 served as an early indicator of the underlying script fault. At that time, the company re-signed the lists using the existing weak keys rather than identifying the root cause. This oversight allowed the compromised infrastructure to remain operational for several additional months.
7Operational Wind-Down Strategy
Following the discovery of these vulnerabilities, eMudhra has decided to exit the SSL/TLS certification business. The company is currently undergoing an independent review by KPMG, expected to conclude by December 4. Additionally, a full inventory of all remaining CA keys is scheduled for completion by November 30 to ensure further integrity.
8Lessons in Cryptographic Governance
This incident highlights the dangers of using custom scripts for sensitive cryptographic operations outside of standard hardware security module functions. While eMudhra reports no known cases of misuse, the ability to impersonate websites remains a significant risk. Future operations will focus on strengthening PKI controls based on the independent review findings.