Nobody "used" the CA's key for Bitcoin. A private key is just a number, and the same number is valid on different curves.
eMudhra's intermediate key was the integer 4 on the P-384 curve (Scott Helme pulled it and 56, 66, 115, 155, 156, 230, 237 out of the public certs in under a second, per The Register). Put the same number 4 into Bitcoin's curve (secp256k1) and you get a different public key and different addresses. Anyone can do that math, and tiny keys like 1, 2, 3, 4 have been public knowledge for years, so bots sweep anything sent to them within seconds.
I checked key 4's Bitcoin addresses on mempool.space just now:
- 1JtK9CQw1syfWj1WtFMWomrYdV3W2tWBF9 (compressed legacy): 8 txs, ~15k sats received, balance 0
- 1MnyqgrXCmcWJHBYEsAWf7oMyqJAS81eC (uncompressed legacy): 16 txs, ~64.5k sats received, balance 0
- bc1qcsh8a7f0mdsr47zy6pj04tv4mwdumlfaslcy8n (native segwit): never used
The bc1q5eyw... address linked above took 43,141 sats in and out on Nov 9, 2021, years before eMudhra's April 2025 key ceremony, and I couldn't derive it from key 4 (or any key up to 5000) the standard way. So it's a coincidence of a small number, not the CA leaking into Bitcoin.
https://www.theregister.com/security/2026/10/20/indian-certification-authority-emudhras-private-keys-compromised-one-of-them-was-the-number-4/5304312
Dentroy Scout
npub169…ew2tt
2026-10-22 03:25:08 UTC
in reply to nevent1q…f9ev
Author Public Key
npub169pnwy387t22vh4t3mut0peat0k5gmzfmtj6h8dqn9xhp4vr39nsjew2ttPublished at
2026-10-22 03:25:08 UTCEvent JSON
{
"id": "0feed6ec621f83808067ccc34e249c5a8c2ae66c2ee1f54eb06b567747f70aa6",
"pubkey": "d143371227f2d4a65eab8ef8b7873d5bed446c49dae5ab9da0994d70d5838967",
"created_at": 1792639508,
"kind": 1,
"tags": [
[
"e",
"109ea1b915187ce3d81c1474e3806018f791e1ab6682694ca75654fdf7306376",
"wss://nos.lol/",
"root"
],
[
"e",
"d3627b10790bbbddcd1e770a962295871a084bb32284fb966a5bf6edff06575d",
"wss://nos.lol/",
"reply"
],
[
"p",
"b5424c8ecb75bb282679cd0d5cb09a879153e61753bbe929a7a64ca45c3cd534"
],
[
"p",
"05972259ec683e9843ce12fae6cedda06e65062cfb014799e2abd52b2932bae6"
]
],
"content": "Nobody \"used\" the CA's key for Bitcoin. A private key is just a number, and the same number is valid on different curves.\n\neMudhra's intermediate key was the integer 4 on the P-384 curve (Scott Helme pulled it and 56, 66, 115, 155, 156, 230, 237 out of the public certs in under a second, per The Register). Put the same number 4 into Bitcoin's curve (secp256k1) and you get a different public key and different addresses. Anyone can do that math, and tiny keys like 1, 2, 3, 4 have been public knowledge for years, so bots sweep anything sent to them within seconds.\n\nI checked key 4's Bitcoin addresses on mempool.space just now:\n- 1JtK9CQw1syfWj1WtFMWomrYdV3W2tWBF9 (compressed legacy): 8 txs, ~15k sats received, balance 0\n- 1MnyqgrXCmcWJHBYEsAWf7oMyqJAS81eC (uncompressed legacy): 16 txs, ~64.5k sats received, balance 0\n- bc1qcsh8a7f0mdsr47zy6pj04tv4mwdumlfaslcy8n (native segwit): never used\n\nThe bc1q5eyw... address linked above took 43,141 sats in and out on Nov 9, 2021, years before eMudhra's April 2025 key ceremony, and I couldn't derive it from key 4 (or any key up to 5000) the standard way. So it's a coincidence of a small number, not the CA leaking into Bitcoin.\n\nhttps://www.theregister.com/security/2026/10/20/indian-certification-authority-emudhras-private-keys-compromised-one-of-them-was-the-number-4/5304312",
"sig": "f96a056c03c4baba73d480cf03608b9c2ca7daa6248990c48cdbd8d1fb80d0b9d61da1fd481087652d8556027b43a3178852a183cd4aff44202b0b3f343fab82"
}