Eight private keys used to issue web security certificates by Bengaluru-headquartered eMudhra Ltd. have been leaked, sending security teams at major internet browser and operating system developers around the world scrambling to patch their systems to stop trusting the affected certificates.

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The extraordinary development comes as several government websites use a range of eMudhra’s keys to “sign” their security certificates, which is practically necessary for any website to display on a modern browser.

These “intermediate” security certificate keys had a glaring flaw, according to an anonymous researcher who alerted major internet infrastructure firms over the last few days. The uncovered flaw boiled down to this: instead of using a 384-bit private key, these intermediate certificates just had a numerical key that was between 1 and 256, making it orders of magnitude easier to infer them. Public key cryptography, such as that used in web security certificates, or SSL certificates, relies on private keys staying unknown to any outside entities under all circumstances. One of the keys was just the number 4, preceded by 383 zeroes. 

The Ministry of Electronics and Information Technology (MeitY ) said in a statement shared with The Hindu that it “has taken serious note of the reported incident,” and that a “special team has been constituted to investigate the matter”. 

The Ministry added that “social media accounts are indulging in fear mongering about the impact of this incident,” and said that issuing web security certificates was “international in nature and operates under global trust framework,” and that the “reported security incident pertains to this only”. The IT Ministry was not involved in the audit of this portion of eMudhra’s operations, it said.

“The impact of this incident on Indian websites and applications have been very limited and for a very short interval,” MeitY said. “Important to note that Digital Signature Certificates and eSign services regulated by Controller of Certifying Authorities (CCA), remains completely unaffected by this incident,” the Ministry added. 

Dennis Jackson, who was involved in Mozilla’s response to the incident, said that eMudhra’s private keys were “trivial to exploit,” adding that “6 of the impacted certificates are for TLS and trusted by the Chrome, Mozilla, Microsoft and Apple root programs”. eMudhra revoked the affected certificates.

“Upon becoming aware of the incident, eMudhra initiated its incident response procedures, took measures to contain the affected certificates, and began working closely with browser and root-store operators to safeguard users and maintain the integrity of the broader WebPKI ecosystem,” eMudhra said in an update posted on its website.

“Importantly, none of the affected intermediate CAs were deployed in production, with the exception of one,” eMudhra said, without identifying which one it was. “Furthermore, none of these intermediate CAs, including the one deployed in production, have issued any end-entity certificates. This has been confirmed through our internal analysis and corroborated by publicly available Certificate Transparency records.”

In a subsequent statement filed in stock exchanges, eMudhra said, “A flaw in the [Key Generation Ceremony] caused a wrap/unwrap step to produce a second set of weak keys alongside the original strong keys.” It added, “The weak keys were the ones published to the browser root stores. eMudhra is working to establish the root cause.”

Yash Kakadia, founder of the Security Brigade cybersecurity firm, said that the impact of this leak, even if patched on browsers, could extend to internet-of-things (IoT) devices that are not frequently patched to address certificate compromise incidents like this. “The cleanup could be enormous, particularly for devices and software that cannot be easily updated,” Mr. Kakadia said.

Many government websites, including the Aadhaar issuer UIDAI and the income tax filing portal, use eMudhra certificates or other technology from the firm.

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There is no indication that eMudhra’s root certificates itself — which sit above the tier that was leaked — have been compromised. Global browsers have been reluctant to trust Indian root certificate authorities since “rogue” certificates were issued in July 2014 by the National Informatics Centre’s root authority. eMudhra is the sole Indian root certificate authority trusted globally.

In 2023, MeitY launched the Indian Web Browser Development Challenge to solicit the development of an Indian-made browser that would trust root CAs by the CCA, which the main web browsers today block. Zoho Corp’s Ulaa won the challenge, winning ₹1 crore.