Messages and digests

This page collects every exact format. Unless stated otherwise, ‖ is byte concatenation and integers in Kaspa digests are 8-byte little-endian and must not be negative.

Kaspa digests (signed with Schnorr)

Mint digest

BLAKE3( "kUSDT/mint/v1" ‖ covenant_id[32] ‖ chain[1] ‖ first_nonce[8]
        ‖ for each recipient (1 to 3): owner_scheme[1] ‖ owner[32] ‖ amount[8] )

Signed by 3 distinct signers. Signatures are 64-byte Schnorr signatures over the 32-byte digest, checked with OpCheckSigFromStack. They are passed with the signer indices (0 to 4) in strictly increasing order.

Govern digest

BLAKE3( "kUSDT/govern/v1" ‖ covenant_id[32] ‖ admin_nonce[8] ‖ action[1] ‖ params )

Action	Code	`params`	Length	Quorum
`unpause`	`0x01`	none	0	4
`set_limits`	`0x02`	`capacity[8] ‖ refill_per_daa[8]`	16	4
`set_signers`	`0x03`	`signer_set[32] ‖ guardian[32]`	64	4
`skip_nonce`	`0x04`	`chain[1] ‖ nonce[8]`; the nonce must be the chain’s current one	9	4
`set_value`	`0x05`	`value[8]`, the minter’s own KAS deposit in sompi, above 0	8	3

Each accepted action moves admin_nonce forward by one, so every governance message is single-use.

Signer set

signer_set = BLAKE3( k₀ ‖ k₁ ‖ k₂ ‖ k₃ ‖ k₄ )      // the five 32-byte x-only Schnorr keys, in order

BridgeMint stores only this hash. A mint or governance transaction supplies all five keys; the covenant hashes them and compares.

Pause

pause takes no digest. The guardian signs the transaction itself (a normal transaction signature), and the covenant checks it against the stored guardian key.

EVM messages (signed with ECDSA, EIP-712)

Domain

EIP712Domain { name: "kUSDT Vault", version: "1", chainId, verifyingContract }

chainId and verifyingContract make every signature specific to one vault on one chain.

Types

Release(bytes32 redeemId,address recipient,uint256 units)
Refund(uint64 nonce,address recipient,uint256 units)

Type	Type hash (`keccak256` of the type string)
`Release`	`db81a01974a4adb35845f457adf2050874165e1d4b664b7d8094e6b4675adc22`
`Refund`	`539b8e204dd36db72fc7fd5517acb891dea7731575f151f5085a553c9a839946`

The type hashes were computed from the type strings; the vault exposes its own as RELEASE_TYPEHASH and REFUND_TYPEHASH, and its digests as releaseDigest(r) and refundDigest(r).

At least 3 signatures. The recovered signer addresses must be strictly increasing, which proves they are distinct. The vault uses OpenZeppelin’s ECDSA.recover, which rejects malleable (high-s) signatures.

Redeem ID

redeemId = keccak256( abi.encodePacked("kusdt/redeem/v1", bytes32 kaspaTxId, uint32 outputIndex) )

Kaspa scripts and payloads

Burn script and burn owner

R(chain, address) = 6a ‖ 0f ‖ "kUSDT/redeem/v1" ‖ 01 ‖ chain ‖ 14 ‖ address[20]
burn owner        = owner_scheme 0x03, owner = BLAKE2b-256(R)

Redemption payload

"KUSDT" ‖ 01 ‖ count[1] ‖ count × ( output_index[1] ‖ chain[1] ‖ address[20] )

Metadata payload (KCC-23)

0x00 ‖ UTF-8 JSON object        // in the version 1 preparation transaction

Details: Burn owner and payload, Token metadata.

EVM events

event Deposit(uint64 indexed nonce, address indexed sender, uint8 ownerScheme,
              bytes32 owner, uint256 units, uint256 fee, uint256 minted);
event Released(bytes32 indexed redeemId, address indexed recipient,
               uint256 units, uint256 fee, uint256 payout);
event Refunded(uint64 indexed nonce, address indexed recipient, uint256 units);

Administrative events: FeesSet, DepositLimitsSet, ReleaseLimitsSet, SignersSet, GuardianSet, FeesWithdrawn, and OpenZeppelin’s Paused, Unpaused, OwnershipTransferStarted and OwnershipTransferred.

Domain separation

String	Used in
`kUSDT/mint/v1`	Mint digest
`kUSDT/govern/v1`	Govern digest
`kUSDT/redeem/v1`	Burn script `R`
`kusdt/redeem/v1`	EVM redeem ID
`KUSDT`	Redemption payload magic
`kUSDT Vault`, version `1`	EIP-712 domain