specs/03.md

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_i = channel address to be established:
• • Let to_self = cbytes(pk_i).
• • Let Q_i, gacc_i, and tacc_i = keygen_ctx_i.
• • Let agg_key = xbytes(Q_i).
• • 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]