One CA’s Private Key Was the Number 4 — eMudhra Exits TLS Today

EMudhra, an Indian certificate authority trusted by major browsers, is exiting the publicly trusted TLS business, with its last certificates issuing today, after security researcher Scott Helme cracked all eight compromised private keys on a personal laptop in under a second. The compromised keys included a P-384 ECDSA key with the value 4, reducing what should be roughly 384 bits of entropy to a single digit. The failure traces to April 2025, and an AI agent later reproduced the key cracking from a single prompt.

An Indian certificate authority trusted by every major browser had a private key with the value 4. Not “weak” in the password-manager sense — the integer 4. A P-384 ECDSA key that should carry around 384 bits of entropy was reduced to a single digit. Security researcher Scott Helme cracked all eight compromised keys on a personal laptop in under a second. An AI agent later did it from one prompt. eMudhra, the CA responsible, is exiting the publicly trusted TLS business entirely — the last certificates issue today. What Went Wrong in April 2025 The failure traces to a … The post