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+BDS-03 Base Channel Formation
+======
+`draft` `mandatory` `author:brqgoo`
+
+This BDS defines the channel formation protocol for crediting channel addresses.
+
+## Channel Establishment
+
+        +-------+                                     +-------+
+        |       |--(1)---    request_base_form  ----->|       |
+        |       |<-(2)--      accept_base_form  ----- |       |
+        |  CLI  |                                     |  LSP  |
+        |       |--(3)---     refund_state_sig  ----->|       |
+        |       |<-(4)--        credit_base     ----- |       |
+        +-------+                                     +-------+
+
+### The `request_base_form` Message
+
+This message contains information about the channel address outpoint info for which the user wants to be credited by the LSP.
+
+ -  For _addr<sub>i</sub> = channel address to be established_:
+- - Let _to_self_ = _cbytes(pk<sub>i</sub>)_.
+- - Let _Q<sub>i</sub>_, _gacc<sub>i</sub>_, and _tacc<sub>i</sub>_ = _keygen_ctx<sub>i</sub>_.
+- - Let _agg_key_ = _xbytes(Q<sub>i</sub>)_.
+- - Let _secnonce_, _pubnonce_ = _NonceGen(to_self, agg_key)_.
+- - Let `child_key_cli` = _bytes(32, to_self)_.
+- - Let `public_nonce_cli` = _bytes(32, pubnonce)_.
+
+`request_base_form` payload:
+   * [`32*byte`:`channel_addr_prevout`]
+   * [`u64`:`channel_addr_vout`]
+   * [`32*byte`:`child_key_cli`]
+   * [`32*byte`:`public_nonce_cli`]
+
+### The `accept_base_form` Message
+
+
+- -  Let _to_self_ :  32-byte x-only well defined LSP key.
+- -  Let _to_remote_ :  `child_key_cli` from `request_base_form` message.
+- -  Let _keygen_ctx_ = _KeyAgg([to_self, to_remote])_.
+- -  Let _Q_, _gacc_, and _tacc_ = _keygen_ctx_.
+- - Let _agg_key_ = _xbytes(Q)_.
+- - Let _secnonce_, _pubnonce_ = _NonceGen(to_self, agg_key)_.
+- - Let `public_nonce_lsp` = _bytes(32, pubnonce)_.
+
+`accept_base_form` payload:
+   * [`32*byte`:`channel_addr_prevout`]
+   * [`u64`:`channel_addr_vout`]
+   * [`32*byte`:`public_nonce_lsp`]
+
+### The `refund_state_sig` Message
+
+
+`refund_state_sig` payload:
+   * [`32*byte`:`channel_addr_prevout`]
+   * [`u64`:`channel_addr_vout`]
+   * [`32*byte`:`half_sig_cli`]
+
+### The `credit_base` Message
+
+
+`credit_base` payload:
+   * [`32*byte`:`channel_addr_prevout`]
+   * [`u64`:`channel_addr_vout`]
+   * [`32*byte`:`half_sig_lsp`]