eMudhra exits global SSL business after weak keys found

Indian certificate authority eMudhra announced on Thursday that it will exit its global SSL/TLS certificate business. The decision follows the discovery by a security researcher that eight of its intermediate Certificate Authority (CA) private keys were critically weak and easily recoverable. Major browser vendors including Google and Mozilla have already moved to distrust the affected root certificates, impacting tens of thousands of websites.

What happened

The incident began on October 17 when a researcher reported to Apple, Google, Microsoft, Mozilla, and eMudhra that eight intermediate CA private keys were compromised. These keys, which should have been large random numbers, were all below the value of 256. This extreme weakness meant that anyone could calculate the private keys almost instantly, effectively breaking the cryptographic trust model for any certificates issued under them. Six of these eight keys were used for website TLS certificates.

In response, Chrome and Firefox blocked the six affected TLS intermediates within hours of the report. Google confirmed that no website certificates from these intermediates had appeared in public Certificate Transparency logs before the block, meaning they likely were not used to issue valid certificates to end-users. eMudhra stated that its systems were not breached and that it never used these specific weak keys to issue certificates to customers. However, the damage to trust was immediate and severe.

Following the disclosure, eMudhra’s board decided to withdraw from the global SSL/TLS market entirely. The company cited that this segment contributes only about 1% of its revenue and involves complex data sovereignty and compliance costs. It also noted that the social media scrutiny surrounding the incident was disproportionate to the business's size. eMudhra will continue to operate its other services, including digital signatures and the CertiNext platform, but will cease issuing new global TLS certificates.

Key details

• Chrome will stop trusting the emSign ECC Root CA - G3 root certificate on the morning of October 27, Pacific time.
• Mozilla decided on October 20 to stop trusting the same root in Firefox, cutting off legitimate certificates chained to it.
• Approximately 30,800 unexpired certificates were chained to the affected root as of October 21, according to Chrome’s count.
• About 99.9% of the affected certificates were issued through InCommon, a service for the higher education community.
• eMudhra estimated that about 30,000 certificates need to be replaced, with 97% issued via the ACME protocol.
• Standard ACME clients do not automatically replace certificates outside their renewal window unless they support ACME Renewal Information (ARI).

Background

To understand the severity, it helps to know how TLS trust works. Browsers and operating systems maintain a "root store" of trusted Certificate Authorities. When a website presents a certificate, the browser checks if it chains back to one of these trusted roots. If the root is removed from the store, as happened with eMudhra’s ECC root, every certificate issued under it becomes untrusted. Users will see security warnings, and automated systems may fail to connect.

The specific failure here involved private keys for intermediate CAs. An intermediate CA sits between the root and the end-user certificate. If an intermediate’s private key is known, an attacker can issue fraudulent certificates for any domain. In this case, the keys were so small (below 256) that they offered no security. While eMudhra claims these keys were not used for issuance, the mere existence of such weak keys in a production environment signals a critical failure in key generation processes.

Why it matters

For teams running self-hosted software or managing internal services, this incident highlights the fragility of relying on a single certificate provider. Even if your public-facing site uses a different CA, internal tools or partner integrations might rely on eMudhra-issued certificates. With Chrome and Firefox removing trust, any service depending on these certificates will break. This includes APIs, microservices, and third-party integrations that validate TLS chains strictly.

The transition process is also complex. Google has instructed operators to immediately acquire new certificates from a different PKI hierarchy. However, moving from an ECC-based root to an RSA-based one, or to a completely different provider, often requires manual intervention. Automated tools like ACME clients may not handle out-of-band replacements smoothly, especially if they lack support for ACME Renewal Information. This creates a surge of manual work for IT and DevOps teams who must track down every affected endpoint.

Furthermore, the incident raises questions about transparency and operational hygiene. eMudhra had published invalid Certificate Revocation Lists (CRLs) in 2025 for similar intermediates, claiming at the time that they fixed the issue by regenerating CRLs with appropriate keys. The recent discovery suggests those fixes may have involved resigning with flawed keys, a detail not disclosed in the earlier report. This lack of clarity makes it difficult for customers to assess the risk of remaining eMudhra roots, such as the G1 RSA root, which is still under review by Chrome.

What you can do

• Audit your inventory for any certificates issued by eMudhra, particularly those chaining to emSign ECC Root CA - G3.
• Check if your services are part of the InCommon federation, as 99.9% of affected certificates belong to this group.
• Replace affected certificates immediately with ones from a different, trusted CA hierarchy, such as Let's Encrypt or a commercial provider.
• Verify that your ACME clients support ACME Renewal Information (ARI) to handle future forced replacements more smoothly.
• Monitor the status of eMudhra’s G1 RSA root, as Chrome has not yet decided whether to keep it in the root store.
• Update monitoring systems to alert on certificate changes and trust issues, ensuring you catch distrusted roots before users do.