Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

BOLT 3 : remove localpubkey and remote_delayedpubkey references #638

Closed
wants to merge 3 commits into from
Closed

BOLT 3 : remove localpubkey and remote_delayedpubkey references #638

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
b61320c
BOLT 3 : swap localpubkey by local_htlcpubkey in HTLC expected_weight
Jul 10, 2019
7253519
BOLT 3 : remove reference to localpubkey
Jul 10, 2019
26e69dc
BOLT 3 : remove reference to remote_delayedpubkey
Jul 10, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
47 changes: 13 additions & 34 deletions 03-transactions.md
View file
Open in desktop
Expand Up @@ -22,7 +22,7 @@ This details the exact format of on-chain transactions, which both sides need to
* [Fee Payment](#fee-payment)
* [Keys](#keys)
* [Key Derivation](#key-derivation)
* [`localpubkey`, `remotepubkey`, `local_htlcpubkey`, `remote_htlcpubkey`, `local_delayedpubkey`, and `remote_delayedpubkey` Derivation](#localpubkey-remotepubkey-local_htlcpubkey-remote_htlcpubkey-local_delayedpubkey-and-remote_delayedpubkey-derivation)
* [`remotepubkey`, `local_htlcpubkey`, `remote_htlcpubkey`, and `local_delayedpubkey` Derivation](#remotepubkey-local_htlcpubkey-remote_htlcpubkey-and-local_delayedpubkey-derivation)
* [`revocationpubkey` Derivation](#revocationpubkey-derivation)
* [Per-commitment Secret Requirements](#per-commitment-secret-requirements)
* [Efficient Per-commitment Secret Storage](#efficient-per-commitment-secret-storage)
Expand Down Expand Up @@ -411,7 +411,8 @@ committed HTLCs:

## Key Derivation

Each commitment transaction uses a unique set of keys: `localpubkey` and `remotepubkey`.
Each commitment transaction uses a unique set of keys: `local_delayedpubkey`, `remote_htlcpubkey`,
`local_htlcpubkey`, `remotepubkey` .
The HTLC-success and HTLC-timeout transactions use `local_delayedpubkey` and `revocationpubkey`.
These are changed for every transaction based on the `per_commitment_point`.

Expand All @@ -426,11 +427,9 @@ avoid storage of every commitment transaction, a _watcher_ can be given the
the scripts required for the penalty transaction; thus, a _watcher_ need only be
given (and store) the signatures for each penalty input.

Changing the `localpubkey` and `remotepubkey` every time ensures that commitment
Changing the set of keys`every time ensures that commitment
transaction ID cannot be guessed; every commitment transaction uses an ID
in its output script. Splitting the `local_delayedpubkey`, which is required for
the penalty transaction, allows it to be shared with the _watcher_ without
revealing `localpubkey`; even if both peers use the same _watcher_, nothing is revealed.
in its output script.

Finally, even in the case of normal unilateral close, the HTLC-success
and/or HTLC-timeout transactions do not reveal anything to the
Expand All @@ -441,21 +440,19 @@ For efficiency, keys are generated from a series of per-commitment secrets
that are generated from a single seed, which allows the receiver to compactly
store them (see [below](#efficient-per-commitment-secret-storage)).

### `localpubkey`, `remotepubkey`, `local_htlcpubkey`, `remote_htlcpubkey`, `local_delayedpubkey`, and `remote_delayedpubkey` Derivation
### ``remotepubkey`, `local_htlcpubkey`, `remote_htlcpubkey`, and `local_delayedpubkey`Derivation

These pubkeys are simply generated by addition from their base points:

pubkey = basepoint + SHA256(per_commitment_point || basepoint) * G

The `localpubkey` uses the local node's `payment_basepoint`;
the `remotepubkey` uses the remote node's `payment_basepoint`;
the `local_htlcpubkey` uses the local node's `htlc_basepoint`;
the `remote_htlcpubkey` uses the remote node's `htlc_basepoint`;
the `local_delayedpubkey` uses the local node's `delayed_payment_basepoint`;
and the `remote_delayedpubkey` uses the remote node's `delayed_payment_basepoint`.
and the `local_delayedpubkey` uses the local node's `delayed_payment_basepoint`;

The corresponding private keys can be similarly derived, if the basepoint
secrets are known (i.e. the private keys corresponding to `localpubkey`, `local_htlcpubkey`, and `local_delayedpubkey` only):
secrets are known (i.e. the private keys corresponding to `local_htlcpubkey`, and `local_delayedpubkey` only):

privkey = basepoint_secret + SHA256(per_commitment_point || basepoint)

Expand Down Expand Up @@ -708,8 +705,8 @@ The *expected weight* of an HTLC transaction is calculated as follows:
- OP_EQUALVERIFY: 1 byte
- 2: 1 byte
- OP_SWAP: 1 byte
- OP_DATA: 1 byte (localpubkey length)
- localpubkey: 33 bytes
- OP_DATA: 1 byte (local_htlcpubkey length)
- local_htlcpubkey: 33 bytes
- 2: 1 byte
- OP_CHECKMULTISIG: 1 byte
- OP_ELSE: 1 byte
Expand Down Expand Up @@ -742,8 +739,8 @@ The *expected weight* of an HTLC transaction is calculated as follows:
- OP_DROP: 1 byte
- 2: 1 byte
- OP_SWAP: 1 byte
- OP_DATA: 1 byte (localpubkey length)
- localpubkey: 33 bytes
- OP_DATA: 1 byte (local_htlcpubkey length)
- local_htlcpubkey: 33 bytes
- 2: 1 byte
- OP_CHECKMULTISIG: 1 byte
- OP_ELSE: 1 byte
Expand Down Expand Up @@ -921,7 +918,6 @@ And, here are the keys needed to create the transactions:
local_funding_pubkey: 023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb
remote_funding_pubkey: 030e9f7b623d2ccc7c9bd44d66d5ce21ce504c0acf6385a132cec6d3c39fa711c1
local_privkey: bb13b121cdc357cd2e608b0aea294afca36e2b34cf958e2e6451a2f27469449101
localpubkey: 030d417a46946384f88d5f3337267c5e579765875dc4daca813e21734b140639e7
remotepubkey: 0394854aa6eab5b2a8122cc726e9dded053a2184d88256816826d6231c068d4a5b
local_delayedpubkey: 03fd5960528dc152014952efdb702a88f71e3c1653b2314431701ec77e57fde83c
local_revocation_pubkey: 0212a140cd0c6539d07cd08dfe09984dec3251ea808b892efeac3ede9402bf2b19
Expand Down Expand Up @@ -1501,8 +1497,7 @@ seeded with `0x000...00`.

# Appendix E: Key Derivation Test Vectors

These test the derivation for `localpubkey`, `remotepubkey`, `local_htlcpubkey`, `remote_htlcpubkey`, `local_delayedpubkey`, and
`remote_delayedpubkey` (which use the same formula), as well as the `revocationpubkey`.
These test the derivation for `remotepubkey`, `local_htlcpubkey`, `remote_htlcpubkey`, and `local_delayedpubkey` (which use the same formula), as well as the `revocationpubkey`.

All of them use the following secrets (and thus the derived points):

Expand All @@ -1511,22 +1506,6 @@ All of them use the following secrets (and thus the derived points):
base_point: 0x036d6caac248af96f6afa7f904f550253a0f3ef3f5aa2fe6838a95b216691468e2
per_commitment_point: 0x025f7117a78150fe2ef97db7cfc83bd57b2e2c0d0dd25eaf467a4a1c2a45ce1486

name: derivation of pubkey from basepoint and per_commitment_point
# SHA256(per_commitment_point || basepoint)
# => SHA256(0x025f7117a78150fe2ef97db7cfc83bd57b2e2c0d0dd25eaf467a4a1c2a45ce1486 || 0x036d6caac248af96f6afa7f904f550253a0f3ef3f5aa2fe6838a95b216691468e2)
# = 0xcbcdd70fcfad15ea8e9e5c5a12365cf00912504f08ce01593689dd426bca9ff0
# + basepoint (0x036d6caac248af96f6afa7f904f550253a0f3ef3f5aa2fe6838a95b216691468e2)
# = 0x0235f2dbfaa89b57ec7b055afe29849ef7ddfeb1cefdb9ebdc43f5494984db29e5
localpubkey: 0x0235f2dbfaa89b57ec7b055afe29849ef7ddfeb1cefdb9ebdc43f5494984db29e5

name: derivation of private key from basepoint secret and per_commitment_secret
# SHA256(per_commitment_point || basepoint)
# => SHA256(0x025f7117a78150fe2ef97db7cfc83bd57b2e2c0d0dd25eaf467a4a1c2a45ce1486 || 0x036d6caac248af96f6afa7f904f550253a0f3ef3f5aa2fe6838a95b216691468e2)
# = 0xcbcdd70fcfad15ea8e9e5c5a12365cf00912504f08ce01593689dd426bca9ff0
# + basepoint_secret (0x000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f)
# = 0xcbced912d3b21bf196a766651e436aff192362621ce317704ea2f75d87e7be0f
localprivkey: 0xcbced912d3b21bf196a766651e436aff192362621ce317704ea2f75d87e7be0f

name: derivation of revocation pubkey from basepoint and per_commitment_point
# SHA256(revocation_basepoint || per_commitment_point)
# => SHA256(0x036d6caac248af96f6afa7f904f550253a0f3ef3f5aa2fe6838a95b216691468e2 || 0x025f7117a78150fe2ef97db7cfc83bd57b2e2c0d0dd25eaf467a4a1c2a45ce1486)
Expand Down