eMudhra’s keys: What experts say went wrong, and what companies must do now
eMudhra is at the centre of a wider discussion on digital security, with experts highlighting potential vulnerabilities and the need for stronger safeguards.
eMudhra’s security incident has raised questions about what went wrong and the risks facing businesses that rely on digital trust infrastructure.
NEW DELHI: Eight intermediate certificates run by eMudhra, the listed Bengaluru-based digital certificate provider, were protected by private keys so weak that anyone could recover them in under a second. Google, Mozilla, Apple and Microsoft have blocked them, and the Indian government has opened a probe.
One of the keys was the number 4. All eight were whole numbers below 256, so they could be found by trying 256 possibilities, against the roughly 384 bits of randomness a key of this type should carry. Anyone holding such a key could in theory forge certificates that browsers would accept for any website, though they would still need to intercept a victim’s connection to use them. Six of the eight certificates were for websites and two were for signing software.
A security researcher flagged the problem to browser makers on October 17. Chrome blocked the certificates that evening and Firefox followed within hours. eMudhra revoked all eight the next day. Apple blocked them on October 19 and Microsoft on October 20. Mozilla has also removed the root under which they sat, emSign ECC Root CA – G3, and Google will drop it from Chrome on October 27, after which websites whose certificates chain to it may show errors.
eMudhra has blamed a script flaw at a key-generation ceremony on April 30, 2025, for 24 subordinate certificate authorities. A wrap-and-unwrap step produced a second, weak set of keys alongside the intended ones, and because the labels were similar, the weak ones were used to build the certificates. The company says its infrastructure was not breached and no customer data was exposed, that only one of the eight was ever used in production, and that none issued certificates to customers. It estimates about 30,000 certificates chaining to the affected root will have to be reissued.
eMudhra: Why it reaches beyond eMudhra’s customers
Certificate authorities vouch for the identity of websites, and an intermediate certificate lets them do that at scale. The private key is what makes it work. “If someone can recover that key, they can create fake certificates for domains they do not own,” said Saurabh Pandya, who works on information security and IT services at Beyond Key, an IT consulting and software services firm.
The damage is not limited to the authority’s own clients. “A browser may trust a fake certificate because it recognises the issuing authority, even if the website has never dealt with that authority directly,” Pandya said.
So far, the damage looks contained. Mozilla cryptography engineer Dennis Jackson’s tracking page on the incident says no certificates from these intermediates appear in public Certificate Transparency logs, which means clients that enforce those logs could not have been attacked. Pandya cautioned that this cannot rule out abuse against software that skips the check, and the keys sat unnoticed for more than 17 months.
Malcolm Gomes, chief operating officer of identity verification company IDfy, called it “a serious failure with limited impact so far.” Forged certificates are “a tool for targeted attacks rather than mass ones,” he said. The most exposed would be systems that skip browser-grade checks, such as mobile apps, partner and payment integrations and older internal software. “For banks and insurers, that’s where a lot of customer data moves,” Gomes said.
eMudhra: Process, not just a bug
eMudhra has said its roots and issuing authorities passed independent audits two years running. That is what troubles the experts. Gomes said the scripting error may well be a one-off, but “the fact that it passed every layer of review is a process failure.” In his view, three checks should have caught it: testing each key against its certificate before issue, scanning it for known weaknesses, which takes seconds, and independently reviewing the script beforehand.
Pandya said the person witnessing a ceremony must do more than watch. “A second authorised person should confirm those checks using evidence, not just witness the procedure,” he said.
Bharat Joshi, co-founder and chief product officer of observability firm VuNet Systems, said the case shows how long such flaws can hide. “A weakness introduced during certificate generation can remain unnoticed for a long time,” he said.
The regulator now has a question of its own to answer. Pandya said the Controller of Certifying Authorities should obtain “evidence that the separation of the two is both real and enforced through technical means,” including key inventories and hardware security module logs. Gomes said the regulator should ask whether the same teams, tools or scripts were used for keys under the Indian hierarchy, whether those keys have been tested by someone outside the company, and whether audits examine the keys themselves or only the paperwork around them.
eMudhra: What companies should do
Firms that bought eMudhra certificates need to find the ones chaining to the affected root and replace them. “The immediate priority should be to identify any affected certificates and replace them ASAP,” Joshi said. Pandya advised inspecting the full certificate chain, telling the provider, moving to an unaffected hierarchy and testing dependent services, without assuming every application shares one trust store. Gomes said software with its own certificate stores may keep trusting the compromised intermediates until it is updated, and urged companies to watch public logs for any certificate issued in their name.
The episode is also a prompt to check what cyber insurance actually covers. Such policies are designed to move losses from data breaches, cybercrime, network interruption and third-party claims to insurers, and many insurers ask for a security audit before issuing cover, the same kind of audit-based assurance the eMudhra lapse has put under scrutiny. With CERT-In reporting no confirmed exploitation or customer-data breach, there is no known loss for a policy to respond to yet.
The wider lesson, Gomes said, is what the web counts as proof. “The web trusts certificate authorities largely on the strength of audits, and audits check process,” he said. “These keys were found by a researcher using publicly available data, which means anyone could have tested them at any point. Trust in the authorities, and in every vendor your customers depend on, should be verified continuously.”
