Disgraced Former eMudhra Blames Python Bug for Weak Keys
eMudhra, the Indian certificate issuer that quit the SSL/TLS business after its private keys were found to be trivially weak, now says a buggy Python script caused the failure. The company posted its account on Bugzilla, citing hardware shortages and a missed testing step.
Disgraced former certificate authority eMudhra blames a buggy Python script for issuing digital certificates with laughably weak private keys, according to an account the company posted on Bugzilla, the bug tracker used by browser maker Mozilla.
The post came from a user named Naveen Kumar ML. It is the company's fullest explanation yet of how its security failed.
What the script did
Kumar wrote that during a single key-generation ceremony on April 30, 2025, sixteen subordinate (issuing) CA key pairs in eMudhra's "B" and "C" series were created correctly on a hardware security module. They were then processed through a wrap/unwrap round trip using a custom Python key-handling script.
eMudhra aimed to create eight ECDSA P-384 private keys, which should each be 48 bytes long. A defect in the import code truncated the private value when it was read back. As a result, the public keys correspond to private values below the expected range, "recoverable from public information," Kumar wrote.
The effect was that 47 of the 48 bytes were ignored. That produced single-byte keys, including the number four.
Kumar said the script ran only on an isolated ceremony host and "was not a function of the emCA software."
Why it used a workaround
eMudhra said "global supply chain constraints" stopped it from acquiring the hardware security modules it wanted for a set of certificates for use in the USA. Those devices generate and store cryptographic keys.
Instead, it generated keys on modules from Utimaco and planned to move them to modules from Crypto4A. Kumar said the unusual step was needed because policy changes meant new certificates had to be generated by the end of May.
The company did not notice the errors in its script and did not test the keys it created.
Fallout and next steps
A Mozilla team member spotted the weak keys. Attackers could have used them to issue fraudulent certificates, impersonate servers, watch traffic or alter data in transit. Browser makers quickly changed their software so it no longer recognizes eMudhra certificates.
The company then left the SSL/TLS certification business. It said the business was never a major source of revenue but had become a severe source of embarrassment.
Kumar's post lists three steps for winding down the certification operation. One is to "Put in place improvements motivated by findings of [an] independent review to strengthen our general PKI operations."
