Alert Messages

The alert message format is standardized for all message types. Depending on the alert type, the message can vary in format.

Field	Description	Type	Size (bytes)
Version	Alert key message version = 1.	uint32	4
Sequence Number	The alert message sequence number.	uint32	4
Timestamp	Alert -key message timestamp in Unix timestamp / Unix epoch format as (seconds since 1970-01-01T00:00 UTC).	uint32	4
Alert Type	Alert key message type.	uint32	4
Signatures	Signature data concatenated	Signature[N]	65*N
Message	Alert message	Variable Bytes	Depends on alert type

Signatures are calculated on doublesha256(Version || Sequence Number || Time || Alert Type || Message Body), where || is byte concatenation and will be encoded using just r, and s and the 1 byte header to guarantee a fixed length of 65 bytes.

The alert message format for each type is defined elsewhere. The important detail is that the alert type defines what associated action the Alert System should perform.

Prior to the release of Teranode, the Alert System interfaces with SV Node over the RPC interface. Below is a list of the supported Alert Messages and their associated RPC calls:

Alert Type	Description	Type	RPC Call	RPC Parameters
Informational Message	Informational broadcast to the network	0x01	N/A	N/A
Freeze UTXO	Sets a specified UTXO as unspendable until further notice	0x02	addToConsensusBlacklist	UTXO ID vout Enforce at height start Enforce at height end
Unfreeze UTXO	Sets a specified UTXO as spendable	0x03	addToConsensusBlacklist	UTXO ID vout Enforce at height start Enforce at height end
Reassign UTXO	Reassigns a frozen UTXO to a new locking script.	0x04	addTxIdToConfiscationWhitelist	Enforce at height Transaction Hex
Ban Peer	Adds a peer to the node’s ban list.	0x05	setBan	Peer Address
Unban Peer	Removes a peer from the node’s ban list.	0x06	setBan	Peer Address
Invalidate Block	Invalidates a specified block hash, and nodes reject any chains built on top of it.	0x07	invalidateBlock	Block Hash
Set Keys	Sets the public keys associated with the current Alert Key Holders	0x08	N/A	N/A

Alert Messages are valid when they are signed by 3 of 5 current Alert Key Holders. Alert Messages increment by sequence number, and the initial message referenced by sequence number 0 contains the following Set Keys Alert Message:

01000000000000004d181a02070000000800000020d4fca62196f52be20c4e75370ce9af922d6fe8080e0870a66de850928e62aeee5926d1a703bbc5e9671653a4eb88566661b28a5bb53c46914841ef8db2681df420c65c64a800150e36e38be2acc05ccde6522375b40331d5365360c6c4fba3b0864571866668581add73a5d28adb53a3708e6d3608ccf1c8cef1e605cd471e5eba20687ca0813a483f644f7a2c1eab5fd4d1715d428029b6e562682ea9d8c19275cc43ef367507fa26915b498b7c3bd0362d31fcc9fe2495d0c05a17b98764a31bfc

This message is the valid genesis message for the mainnet instance of the Alert System. The public keys associated with this message are:

• 02a1589f2c8e1a4e7cbf28d4d6b676aa2f30811277883211027950e82a83eb2768

• 03aec1d40f02ac7f6df701ef8f629515812f1bcd949b6aa6c7a8dd778b748b2433

• 03ddb2806f3cc48aa36bd4aea6b9f1c7ed3ffc8b9302b198ca963f15beff123678

• 036846e3e8f4f944af644b6a6c6243889dd90d7b6c3593abb9ccf2acb8c9e606e2

• 03e45c9dd2b34829c1d27c8b5d16917dd0dc2c88fa0d7bad7bffb9b542229a9304