eMudhra Apologises After Weak Keys Expose Eight Certificate Authorities, Exits Global SSL/TLS Business

Indian digital trust company eMudhra has apologised publicly after eight of its intermediate certificate authorities (CAs) were found to use easily guessable private keys. It has revoked the affected certificates, says it has no evidence of misuse, and has decided to leave the global SSL/TLS business.

What happened

A security researcher reported on October 17 that the private keys for eight emSign G3 intermediate CAs were recoverable. Digit reports they could be recovered in under a second. Six of the eight were for website (TLS) security and two for code signing. An intermediate CA is a link in the chain that lets browsers trust a website certificate. "The flaw was ours," eMudhra said in its apology.

What went wrong

The keys were meant to be strong P-384 keys generated randomly. A script error during a key generation ceremony produced a second, weak set of keys alongside the strong ones, according to eMudhra and security reports. Similar labels meant the weak keys were used in certificate signing requests. CERT-In said the keys had values smaller than 256, which allowed near-instant recovery from the public keys. The keys were created on April 30, 2025, so they were exposed for almost 18 months.

No evidence of misuse

eMudhra says its investigation found no breach of its infrastructure or customer data and no sign the weak keys were abused. It says none of the affected authorities issued publicly trusted certificates for individual websites or users. Because the keys existed for so long, misuse before disclosure can't be ruled out, and Digit notes this. CERT-In said public disclosures had not confirmed malicious exploitation as of October 21. eMudhra says it revoked the intermediates within 14 hours of the report.

Browsers respond

Google and Mozilla blocked the affected keys on October 17. Mozilla later removed trust in the emSign ECC Root CA – G3 in the root store that signed them, and Chrome is expected to follow on October 27. Apple, Google, Microsoft and Mozilla all blocked the affected certificates, per Digit. Customers holding certificates under that root must reissue them. Mozilla said it is not removing trust in the older emSign Root CA – G1 for now.

eMudhra exits global TLS

On October 22, eMudhra's board decided to voluntarily withdraw from the global SSL/TLS certificate business. It will keep revocation and status services running until all its TLS certificates expire or are replaced, and is offering customers certificates from Sectigo, according to Computerworld.

What users should do

CERT-In's advisory urges organisations to update browsers and operating systems, refresh trusted-certificate lists, replace certificates in the affected chain and never bypass certificate warnings, as reported by Neo Science Hub. Website owners with emSign certificates should check which root they chain to and move to another provider before the Chrome deadline.

What is still open

The researcher questioned a revocation list for eMudhra's G1 root, which eMudhra said had been re-signed with the flawed keys. Whether further distrust follows is for Mozilla and others to decide. It's also unclear how many certificates will need reissuing.