nips/19.md

NIP-19
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bech32-encoded entities
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`draft` `optional` `author:jb55` `author:fiatjaf` `author:Semisol`

This NIP specifies all bech32-encoded entities.

## Bare keys and ids

To prevent confusion and mixing between private keys, public keys and event ids, which are all 32 byte strings. bech32-(not-m) encoding with different prefixes can be used for each of these entities.

These are the possible bech32 prefixes:

  - `npub`: public keys
  - `nsec`: private keys
  - `note`: note ids

Example: the hex public key `3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d` translates to `npub180cvv07tjdrrgpa0j7j7tmnyl2yr6yr7l8j4s3evf6u64th6gkwsyjh6w6`.

The bech32 encodings of keys and ids are not meant to be used inside the standard NIP-01 event formats or inside the filters, they're meant for human-friendlier display and input only. Clients should still accept keys in both hex and npubformat for now, and convert internally.

## Shareable identifiers with extra metadata

When sharing a profile or an event, an app may decide to include relay information and other metadata such that other apps can locate and display these entities more easily.

For these events, the contents are a binary-encoded list of `TLV` (type-length-value), with `T` and `L` being 1 byte each (`uint8`, i.e. a number in the range of 0-255), and `V` being a sequence of bytes of the size indicated by `L`.

These are the possible bech32 prefixes with `TLV`:

  - `nprofile`: a nostr profile
  - `nevent`: a nostr event

These possible standardized `TLV` types are indicated here:

- `0`: `special`
  - depends on the bech32 prefix:
    - for `nprofile` it will be the 32 bytes of the profile public key
    - for `nevent` it will be the 32 bytes of the event id
- `1`: `relay`
  - A relay in which the entity (profile or event) is more likely to be found, encoded as UTF-8. This may be included multiple times.