Decoupled Encryption Key

draft optional

Defines a protocol for decoupling the encryption key per NIP-4E using user metadata events per NIP-Metadata.

Kind 34578 — User Metadata Event

Stores the secret metadata information about the user(encryption key) inside the content field. It is identified by the d tag

Tags:

Content: NIP-44 encrypted to the author's own pubkey (via identity signer). Plaintext is a JSON string. Currently, the proposal is that the data contains a encryptionKey attribute which will have the key used for decrypting/encrypting messages, files and other entities owned by the user.

{
  "encryptionKey": "<hex-encoded drive private key>"
}

The conversation key used for all file metadata is:

conversationKey = getConversationKey(driveSecretKey, getPublicKey(driveSecretKey))

Directives

• The user metadata event must have a d tag "0:<author-pubkey>".
• Clients MUST encrypt and decrypt the user metadata event using the identity signer (nip44Decrypt(authorPubkey, content)/nip44Encrypt(authorPubkey, content)).
• Clients MAY generate and publish a new metadata event warning the user that previous events may be lost.
• When multiple events share the same d tag, clients MUST use the one with the highest created_at. Clients MAY inform the user that they found multiple metadata events

Examples

User metadata event:

{
  "kind": 34578,
  "pubkey": "abc123...",
  "created_at": 1700000000,
  "tags": [
    ["d", "0:abc123..."],
  ],
  "content": "<nip44-ciphertext of {\"encryptionKey\",\"deadbeef...\"}>",
  "sig": "..."
}