eMudhra issued TLS certificates with private keys of 3 to 8 bits
Original title: Compromised TLS Certificates
Eight P-384 keys held only a handful of bits of entropy, so a network attacker could impersonate the certificate holder.
Indian certificate authority eMudhra Limited issued eight TLS certificates whose elliptic-curve private keys contained about 3 to 8 bits of entropy instead of a normal NIST P-384 key. Researchers said the keys were the integers 4, 56, 66, 115, 155, 156, 230 and 237. Using them requires an active adversary-in-the-middle position; VPN users and people on local networks are the immediate concern. eMudhra was not available for comment, and the cause of the weak keys is not established.
Unconfirmed: The cause is only guessed—example code or a size parameter set to 1—and eMudhra has not confirmed it.
- A normal NIST P-384 private key has roughly 384 bits of entropy.
- The eight keys were 4, 56, 66, 115, 155, 156, 230 and 237.
- Certificate transparency logs revealed the certificates only after issuance.
- Bruce Schneier posted the account on October 23, 2026.
Impact: Decrypt or impersonate TLS sessions via an on-path attacker
| Product | Affected |
|---|---|
| eMudhra Limited TLS certificates | eight certificates with 3- to 8-bit private keys |
- 1.Avoid non-browser TLS that relies on the affected certificates until updates are confirmed.
- 2.Watch certificate transparency logs for unauthorized eMudhra certificates.
- Vendors
- eMudhra Limited
- Countries
- India
From the original article
2 min read at schneier.comThe Indian CA eMudhra Limited has eight TLS certificates with laughably weak private keys: The compromised eMudhra keys were defective at a level that’s challenging the imagination of many of the engineers studying the incident. A normal size for a NIST P-384 elliptic curve cryptography private key contains roughly 384 bits of entropy, a size allowing almost 2384, or a number with 116 digits, different possibilities.
By Bruce Schneier · schneier.com
A short excerpt; the article and its images belong to the publisher. Summary, key facts and assessment above are AI-written from the article and can be wrong.