eMudhra Limited, an India-based certificate authority, is withdrawing from the global SSL/TLS business following the discovery that it issued eight intermediate TLS credentials with critically weak private encryption keys—one as low as 4 bits.
Chairman V. Srinivasan cited three reasons: escalating compliance costs, the fact that TLS certificates contributed only 1 percent of company revenue, and intensifying competition from free certificate providers. The company also noted that social media scrutiny over the incident disproportionately affected a marginal business unit.
The eight compromised certificates contained private keys with entropy levels of 3 to 8 bits—a catastrophic deviation from the NIST P-384 elliptic curve standard, which should generate keys with approximately 384 bits of entropy. The weakest keys offered only 256 possibilities; secure keys should offer 2^384. The vulnerable keys were identified as: 4, 56, 66, 115, 155, 156, 230, and 237.
Browser makers moved within one to two days to revoke certificates issued with these compromised intermediates. eMudhra faced potential revocation of its certificate authority status by the CA/Browser Forum, the industry body governing TLS program participation.
eMudhra traced the flaw to its April 30, 2025 Key Generation Ceremony, which relied on FIPS 140-2 Level 3 Hardware Security Modules. A malfunction in the wrap/unwrap cryptographic process—which manages key operations within the HSMs—generated a second set of weak keys that were inadvertently published to browser root stores. The company is still investigating the precise failure point.
