Merge b63beba5e26c559fe806e4a7eade6df84ed9355a into 0619f370bca3485bb9c5870bc2defa03c7c3d10e

17.md

@@ -130,7 +130,7 @@ Clients CAN offer disappearing messages by setting an `expiration` tag in the gi
 
 ## Publishing
 
-Kind `10050` indicates the user's preferred relays to receive DMs. The event MUST include a list of `relay` tags with relay URIs.
+Kind `10050` indicates the user's preferred relays to receive DMs based on [NIP-51](51.md). The event MUST include a list of `relay` tags with relay URIs.
 
 ```jsonc
 {
@@ -146,6 +146,100 @@ Kind `10050` indicates the user's preferred relays to receive DMs. The event MUS
 
 Clients SHOULD publish kind `14` events to the `10050`-listed relays. If that is not found that indicates the user is not ready to receive messages under this NIP and clients shouldn't try.
 
+## Seen status
+
+A client MAY publish a kind `30010` which means saw messages with a `"d"` tag set to receivers pubkey.
+
+The `.content` field has 4 sections separated by `:`:
+
+1. The number of bits in the bit array,
+2. The number of hash rounds applied.
+3. The Base64 encoded string of a bloom filter containing message ids (gift wrapped) saw by receiver.
+4. The salt encoded in the Base64.
+
+The sender pubkey's client MAY query that specific event to check which messaged in this chat is seen by receiver to enhance user experience.
+
+Bloom filters MUST use `SHA256` functions applied to the concatenation of the key, salt, and index, as demonstrated in the pseudocode below:
+
+```js
+class BloomFilter(size: Int, rounds: Int, buffer: ByteArray, salt: ByteArray) {
+    val bits = BitArray(buffer)
+
+    fun bitIndex(value: ByteArray, index: Byte) {
+        return BigInt(sha256(value || salt || index)) % size
+    }
+
+    fun add(id: HexID) {
+        val value = id.hexToByteArray()
+
+        for (index in 0 until rounds) {
+            bits[bitIndex(value, index)] = true 
+        }
+    }
+
+    fun mightContains(id: HexID): Boolean {
+        val value = id.hexToByteArray()
+
+        for (index in 0 until rounds) {
+            if (!bits[bitIndex(value, index)]) {
+                return false
+            }
+        }
+
+        return true
+    }
+
+    fun encode() {
+        return size + ":" + rounds + ":" + base64Encode(bits.toByteArray()) + ":" + base64Encode(salt) 
+    }
+
+    fun decode(str: String): BloomFilter {
+        val [sizeStr, roundsStr, bufferB64, saltB64] = str.split(":")
+        return BloomFilter(sizeStr.toInt(), roundsStr.toInt(), base64Decode(bufferB64), base64Decode(saltB64))
+    }
+}
+```
+
+Example event for direct chats:
+
+```js
+{
+    "pubkey" : sha256(hkdf(private_key, salt: 'nip17') || "<badbdda507572b397852048ea74f2ef3ad92b1aac07c3d4e1dec174e8cdc962a>"),
+    "kind": 30010,
+    "created_at": 1738964056,
+    "tags": [
+        [
+            "d",
+            "bd4ae3e67e29964d494172261dc45395c89f6bd2e774642e366127171dfb81f5"
+        ]
+    ],
+    "content": "100:10:AAAkAQANcYQFCQoB:hZkZYqqdxcE",
+}
+```
+
+In this example the pubkey `badbdda507572b397852048ea74f2ef3ad92b1aac07c3d4e1dec174e8cdc962a`, has confirmed that they saw the messages with ids of `ca29c211f1c72d5b6622268ff43d2288ea2b2cb5b9aa196ff9f1704fc914b71b` and `460c25e682fda7832b52d1f22d3d22b3176d972f60dcdc3212ed8c92ef85065c` from pubkey `bd4ae3e67e29964d494172261dc45395c89f6bd2e774642e366127171dfb81f5`.
+
+> d tag uses the hkdf defined in [NIP-44](44.md).
+
+Example event for group messages:
+
+```js
+{
+    "pubkey" : sha256(hkdf(private_key, salt: 'nip17') || "<badbdda507572b397852048ea74f2ef3ad92b1aac07c3d4e1dec174e8cdc962a>"),
+    "kind": 30010,
+    "created_at": 1738964056,
+    "tags": [
+        [
+            "d",
+            "bd4ae3e67e29964d494172261dc45395c89f6bd2e774642e366127171dfb81f5"
+        ]
+    ],
+    "content": "100:10:AAAkAQANcYQFCQoB:hZkZYqqdxcE",
+}
+```
+
+A client MAY encrypt the `.content` based on [NIP-44](44.md) for more privacy.
+
 ## Relays
 
 It's advisable that relays do not serve `kind:1059` to clients other than the ones tagged in them.

README.md

@@ -209,6 +209,7 @@ They exist to document what may be implemented by [Nostr](https://github.com/nos
 | `30007`       | Kind mute sets                  | [51](51.md)                            |
 | `30008`       | Profile Badges                  | [58](58.md)                            |
 | `30009`       | Badge Definition                | [58](58.md)                            |
+| `30010`       | Seen Messages                   | [17](17.md)                            |
 | `30015`       | Interest sets                   | [51](51.md)                            |
 | `30017`       | Create or update a stall        | [15](15.md)                            |
 | `30018`       | Create or update a product      | [15](15.md)                            |