InstantSend Messages

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The following network messages all help control the InstantSend feature of Dash. InstantSend uses the masternode network to lock transaction inputs and enable secure, instantaneous transactions. For additional details, refer to the Developer Guide InstantSend section.

clsig

Added in protocol version 70214 of Dash Core

The clsig message is used to indicate a successful ChainLock for the designated block height. The Chainlock ensures that no other blocks can replace the one with the indicated block hash. This determination is made by agreement of a Long-Living Masternode Quorum (LLMQ) which creates the BLS signature in the message.

Once a clsig message is received, clients must reject any other blocks for the indicated block height as described in DIP8 (ChainLocks). This increases security by preventing reorganization of a block with a ChainLock (and all blocks below it).

Bytes	Name	Data type	Description
4	nHeight	int32_t	Block height
32	blockHash	uint256	Block hash
96	sig	CBLSSignature	LLMQ BLS signature Note: serialized using the basic BLS scheme after Dash 19.0 activation

The following annotated hexdump shows a clsig message. (The message header has been omitted.)

Text

c1310100 ................................... Block Height: 78273

03bb286a877135fad3b33ea9cce9a525
e5edc0879411afaff513b30100000000 ........... Block Hash

12a3331fd8d0008804edaaf94c57b491
d36f38f1993d06dfff71df9ec83da463
dcd5497d105932e609016dac075f02df
1259951e3bcebfcc26afc904f6cd92df
7ff9b8c6c2ac9dcc9cb1a7dc7ec03bcc
005574710c3aabc2f8670959cf8bc9b5 ........... LLMQ BLS Signature

islock

Added in protocol version 70214 of Dash Core

🚧

Future deprecation

The isdlock message with expanded features will eventually replace this message. Protocol version 70220 maintains backwards compatibility for older clients.

The islock message is used to provide details of transactions that have been locked by LLMQ-based InstantSend. The message includes the details of all transaction inputs along with the transaction ID and the BLS signature of the LLMQ that approved the transaction lock.

Bytes	Name	Data type	Description
1-9	inputsSize	compactSize uint	Number of inputs
36 * inputsSize	inputs	COutPoint	Outpoints used in the transaction
32	txid	uint256	TXID of the locked transaction
96	sig	byte[]	LLMQ BLS Signature

The following annotated hexdump shows a islock message. (The message header has been omitted.)

Text

02 ......................................... Number of inputs: 2

Input 1
| 05f24f65a9d98ff543ba61f7f0ce9448
| 79632bf2517540a5bd8bde2fe8e94617 ......... Previous outpoint TXID
| 00000000 ................................. Previous outpoint index: 0

Input 2
| 05f24f65a9d98ff543ba61f7f0ce9448
| 79632bf2517540a5bd8bde2fe8e94617 ......... Previous outpoint TXID
| 01000000 ................................. Previous outpoint index: 1

e2e1c797576d8b13c83e929684b9aacd
553c20a34e2d11e38bdcaaf8e1de1680 ........... TXID

0f055c2064885d446f83d51b9bb09892
7ea0375a0f6a3f3402abf158ece67e00
81049b8a8f45d254b64574cef194ef31
197e450fba1196d652f2e1421d3b80ae
f429c10eabd4ab9289e9a8f80f6989b7
a11e5e7930deccc3e11a931fc9524f06 ........... LLMQ BLS Signature (96 bytes)

isdlock

📘

Added in protocol version 70220 of Dash Core

The isdlock message is used to provide details of transactions that have been locked by InstantSend. The message includes all details present in the islock message along with additional version and cycle information introduced by DIP22. This enables nodes to determine what quorum signed the message and validate the signature in the future after the quorum is no longer active. Additional details about the change are available in DIP22 - Making InstantSend Deterministic using Quorum Cycles.

Bytes	Name	Data type	Description
1	version	uint8	The version of the islock message
1-9	inputsSize	compactSize uint	Number of inputs
36 * inputsSize	inputs	COutPoint	Outpoints used in the transaction
32	txid	uint256	TXID of the locked transaction
32	cycleHash	uint256	Block hash of first block of the cycle in which the quorum signing this islock is active
96	sig	byte[]	LLMQ BLS Signature Note: serialized using the basic BLS scheme after Dash 19.0 activation

The following annotated hexdump shows a isdlock message. (The message header has been omitted.)

Text

01 ......................................... Message version: 1
11 ......................................... Number of inputs: 17

Input 1
| d735fb8cb1b2c4f852e090824ed1b671
| 93a6ed82dfb959487c80c9d520ce270b ......... Previous outpoint TXID
| 01000000 ................................. Previous outpoint index: 1

Input 2
| c8ad33361d9dbc2f0a0e981987fa5c9c
| a3df83991dddccab6498ac40d2976423 ......... Previous outpoint TXID
| 01000000 ................................. Previous outpoint index: 1

| [...] .................................... 15 transaction inputs omitted

f3fd4540b5240abfeba62b766754647a
32580ab3be974b0b63ac16d619675fee ........... TXID

ea830004232454df5db2c96b3da3c741
d7729b0a293c967f7647a2731e000000 ........... Cycle hash

9853fbfbc3592a06200e41617d30713f
861586c7503972ecd09d00731f4fcd6c
712a03c37906a14475e0e903e3ea9185
043673aa8e6ff402eaea7adbdf06d2ab
141fdd115a7162904e8a43c8f3efb67d
05870b1b00c88445f77fa9cb1cb16c01 ........... LLMQ BLS Signature (96 bytes)