Former certification authority eMudhra has claimed a buggy Python script is the main reason it issued laughably insecure digital certificates. The company posted its account of the matter on Bugzilla where a user with the handle “Naveen Kumar ML” wrote “During a single key‑generation ceremony on 30 April 2025, sixteen subordinate (issuing) CA key pairs in eMudhra’s ‘B’ and ‘C’ series were generated correctly on a hardware security module and then processed through an approved wrap/unwrap round‑trip using a custom python key‑handling script.” eMudhra aimed to create eight ECDSA P-384 private keys which should have been 48 bytes long. But the script contained what Kumar described as “a bug/defect in the import code [which] resulted in a read‑back from the unwrapped object that truncated the private value, so the certified public keys correspond to private scalars below the expected range and are recoverable from public information.” The truncation is the key problem here, because it appears that eMudhra ignored 47 of the 48 bytes, producing its infamously insecure single-byte keys such as the number four. Whatever the nature of the bug, Kumar asserts it was “a custom script run only on an isolated ceremony host and was not a function of the emCA software.” eMudhra needed that script because “global supply chain constraints” meant it couldn’t acquire the hardware security modules (HSMs), devices that generate and store cryptographic keys, that it wanted to use when creating a set of certificates for use in the USA. It therefore used HSMs made by a company called Utimaco to generate keys and planned to transfer the keys it produced to a different set of HSMs from a company called Crypto4A. Kumar explained that eMudhra decided on that move, which is unusual, because changes to policy about provenance of certificates meant it had to generate new certs by the end of May. The plan went sour when the company didn’t notice the errors in its script and didn’t test the keys it created. The rest is history: a Mozilla team member noticed that the company’s keys were woefully weak and pointed out that attackers could therefore issue fraudulent certificates that allowed them to impersonate servers, observe traffic, or even modify data in transit. Browser-makers quickly tweaked their software so it would not recognize certs from eMudhra. The Indian business then quit the SSL/TLS certification business, which it said was never a major source of revenue but had suddenly become a severe source of embarrassment. Kumar’s new post lists three steps eMudhra will take to wind up its certification business, one of which will see the company “Put in place improvements motivated by findings of [an] independent review to strengthen our general PKI operations.” Sounds like a plan. ®
Source: The Register — Security · 2026-11-12