add BUT-10 draft

README.md

@@ -42,6 +42,7 @@ See the [BUDs](./buds) folder and specifically [BUD-01](./buds/01.md) and [BUD-0
 - [BUD-04: Mirroring blobs](./buds/04.md)
 - [BUD-06: Upload requirements](./buds/06.md)
 - [BUD-08: Nostr File Metadata Tags](./buds/08.md)
+- [BUD-10: Chunked blobs](./buds/10.md)
 
 ## Event kinds
 
@@ -49,6 +50,7 @@ See the [BUDs](./buds) folder and specifically [BUD-01](./buds/01.md) and [BUD-0
 | ------- | ------------------- | ------------------ |
 | `24242` | Authorization event | [01](./buds/01.md) |
 | `10063` | User Server List    | [03](./buds/03.md) |
+| `2001`  | Merkle tree         | [10](./buds/10.md) |
 
 ## License
 

buds/10.md

@@ -0,0 +1,82 @@
+# BUD-10
+
+## Chunked blobs
+
+`draft` `optional`
+
+Breaking large blobs into smaller chunks for distribution
+
+### Chunking method
+
+The client MAY break large blobs into any number or size of chunks. although its recommended to use the size `1Mb` or `4Mb` for small and large chunks
+
+Clients SHOULD not pad the remaining chunk, If clients need privacy they should use random chunk sizes and optionally encrypt the large blob
+
+Clients MUST create a merkle tree using the chunk hashes as the leaf nodes
+
+### Merkle tree encoding
+
+Clients MAY choose to store the merkle tree on nostr relays using the `2001` kind event
+
+The merkle tree MUST be in the format of `[<root hash (Uint8)>, <left>, <right>]`
+
+The merkle tree MUST be stored in the events `content` as a base64 encoded [`CBOR`](https://cbor.io/) object
+
+Clients MUST add an `x` tag with the merkle root to the `2001` event
+
+Example:
+
+```marmaid
+graph TD
+  Root["Root (ABCDEFG)"] --> H1["ABCD"]
+  Root --> H2["EFG"]
+
+  H1 --> H3["AB"]
+  H1 --> H4["CD"]
+  H2 --> H5["EF"]
+  H2 --> H6["G"]
+
+  H3 --> A["A"]
+  H3 --> B["B"]
+  H4 --> C["C"]
+  H4 --> D["D"]
+  H5 --> E["E"]
+  H5 --> F["F"]
+  H6 --> G["G"]
+```
+
+```
+[Unit8(ABCDEFG),
+  [Unit8(ABCD),
+    [Unit(AB),
+      Unit(A),
+      Unit(B)
+    ],
+    [Unit(CD),
+      Unit(C),
+      Unit(D)
+    ]
+  ],
+  [Unit(EFG),
+    [Unit(EF),
+      Unit(E),
+      Unit(F)
+    ],
+    [Unit(G),
+      Unit(G)
+    ]
+  ]
+];
+```
+
+### Metadata
+
+Clients MAY include additional metadata tags in the `2001` event to help other clients know the filename or mime type
+
+Metadata tags:
+  - `name` Filename
+  - `summary` A short summary of the file
+  - `m` Mime type of file
+  - `size` Total size in bytes of the file
+  - `x` Merkle root
+  - `server` (multiple) Recommended servers to download chunks from