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Kind 10013: Private Relay List ​

Overview ​

Private Relay List events (kind 10013) specify a user's preferred relays for storing sensitive private content such as draft events. Unlike other relay lists that expose relay URLs in public tags, this event type keeps the relay information encrypted, providing an additional layer of privacy. The relay URLs are encrypted using NIP-44 encryption with the author's own keys, ensuring that only the author can see which relays are being used for private content.

Specification ​

PropertyValue
Kind Number10013
Event RangeReplaceable
Defined inNIP-37

Content Format ​

The content field contains NIP-44 encrypted private tags listing the relay URLs. The encryption uses the author's own keys, making the content self-encrypted and readable only by the author.

Schema ​

json
"content": "<NIP-44-encrypted JSON array of relay tags>"

The encrypted content, when decrypted, would reveal a JSON array of relay tags:

json
[
  ["relay", "wss://private-relay.example.com"],
  ["relay", "wss://personal-relay.mydomain.com"]
]

Tags ​

Tag NameDescriptionFormatRequired
NoneThis event typically has no public tags[]No

Client Behavior ​

Clients should:

  1. Create Private Relay List events with NIP-44 encrypted relay URLs in the content field
  2. Publish these events to the author's standard write relays as defined in their NIP-65 relay list
  3. When handling private content like drafts:
    • Decrypt the Private Relay List to determine where to publish the private content
    • Publish private events only to these designated private relays
    • Connect to these relays when retrieving the user's private content
  4. Recommend users select relays that:
    • Support authentication (NIP-42)
    • Limit event access to the authenticated author
    • Have privacy-focused policies
  5. Provide clear UI to indicate which relays will receive private content

Relay Behavior ​

Relays that receive private content should:

  1. Implement authentication (NIP-42) to identify users
  2. Restrict access to events, only serving them to their original author
  3. Consider implementing specific privacy guarantees for users
  4. Not leak metadata about which users have private content stored

Use Cases ​

  • Designating secure relays for storing draft events (kind 31234)
  • Managing where private, encrypted content is stored
  • Creating a separation between public and private relays
  • Enabling private content synchronization across devices
  • Protecting sensitive content from being broadly distributed
  • Supporting workflows that involve private work-in-progress content

Example ​

json
{
  "id": "9ae96799eb074be9833be8e061381d1c91ad5d4a7266f86cae2d261e6b885b43",
  "pubkey": "32e1827635450ebb3c5a7d12c1f8e7b2b514439ac10a67eef3d9fd9c5c68e245",
  "created_at": 1684323281,
  "kind": 10013,
  "tags": [],
  "content": "AqBCdwoS7/tPK+QGkPCadJTn8FxGkd24iApo3BR9/M0uw6n4RFAFSPAKKMgkzVMoRyR3ZS/aqATDFvoZJOkE9cPG/TAzmyZvr/WUIS8kLmuI1dCA+itFF6+ULZqbkWS0YcVU0j6UDvMBvVlGTzHz+UHzWYJLUq2LnlynJtFap5k8560=?iv=S3rFeFr1gsYqmQA7bNnNTQ==",
  "sig": "3cb6233d2b7358e70b8a7311d33ec80b9614bb8e5f903378cc8ff34f5e4c9ec9d7c6c3af2903687b89c4deaf485f9edc7e9a7c80afe1b9ff32bee929845cc88"
}

When decrypted, the content might contain:

json
[
  ["relay", "wss://private.myrelay.com"],
  ["relay", "wss://personal-archive.example.org"]
]

Encryption Process ​

To create a Private Relay List, clients should:

  1. Create a JSON array of relay tags for private relays
  2. Encrypt this array using NIP-44 with the author's own public key as the recipient
  3. Store the encrypted content in the event's content field

Pseudocode:

private_relays = [
  ["relay", "wss://private.myrelay.com"],
  ["relay", "wss://personal-archive.example.org"]
]
encrypted_content = nip44.encrypt(json.stringify(private_relays), user_private_key, user_public_key)
event.content = encrypted_content

References ​

Notes ​

  • The privacy of this system relies on relays implementing proper authentication and access control
  • Relays must enforce that only the original creator of an event can access it
  • Unlike other relay lists, this list is encrypted to protect the user's choice of private relays
  • When functioning properly, this system creates a private space within the Nostr ecosystem
  • Users should be cautious about which relays they trust with private content
  • Clients should publish the Private Relay List to the user's standard write relays to ensure it's discoverable across devices