"... this impossible requirement ..."
You can literally go ahead and use it today. It's not even especially difficult.
For example, here is a cold storage identity if you'd like to see one in action:
https://www.inkan.cc/users/npub10ukg94kvrvk4qqr3482zdekfsuaw2x56wa899mnpkxqwfxl6dlkqrux0x9
The privkey for that one has never come close to a networked device.
inkan
npub16x…56z6l
2026-09-07 16:25:56 UTC
in reply to nevent1q…jwmm
Author Public Key
npub16xnpfx85k8wzdhctang6860g3u64lds5kac73ddjwlg0lxdg9g3su56z6lSeen on
wss://relay.mostr.pubPublished at
2026-09-07 16:25:56 UTCEvent JSON
{
"id": "e0e2a72f6e9a337b3a3d690bd759c451397798a866e6874ef5cb462b7e904715",
"pubkey": "d1a61498f4b1dc26df0becd1a3e9e88f355fb614b771e8b5b277d0ff99a82a23",
"created_at": 1788798356,
"kind": 1,
"tags": [
[
"e",
"0bb4daf107c109410d85a15391dd4961e47fa97cfc7d35f83c1a1df0bb44d531",
"wss://nostr.mom/",
"root",
"50d94fc2d8580c682b071a542f8b1e31a200b0508bab95a33bef0855df281d63"
],
[
"e",
"a9cfbe9da6a497ef727cc0b068c5b465174766325575ce65aad8545b0a027596",
"wss://relay.primal.net/",
"reply",
"5ea4648045bb1ff222655ddd36e6dceddc43590c26090c486bef38ef450da5bd"
],
[
"p",
"aa0f05bad5cf46487338cace55fc2b7cb8e69de6fea4317d3334474369169de8"
],
[
"p",
"50d94fc2d8580c682b071a542f8b1e31a200b0508bab95a33bef0855df281d63"
],
[
"p",
"5ea4648045bb1ff222655ddd36e6dceddc43590c26090c486bef38ef450da5bd"
]
],
"content": "\"... this impossible requirement ...\"\n\nYou can literally go ahead and use it today. It's not even especially difficult.\n\nFor example, here is a cold storage identity if you'd like to see one in action:\n\nhttps://www.inkan.cc/users/npub10ukg94kvrvk4qqr3482zdekfsuaw2x56wa899mnpkxqwfxl6dlkqrux0x9\n\nThe privkey for that one has never come close to a networked device.",
"sig": "e8a2dc86c8a02091d266c344364a6a2bd066e67d609d9aa14de6cc0eea1e7638ef82d60f54ea1f303eb4d09effae541e25aed11f93bb5b4c634145e130f64e8f"
}