Dash Core

Dash Core Developer Documentation

Welcome to the Dash Core developer documentation. You'll find guides and documentation to help you start working with Dash Core as quickly as possible, as well as support if you get stuck. Let's jump right in!

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Control Messages

The following networknetwork - The Dash P2P network which broadcasts transactions and blocks. messages all help control the connection between two peerspeers - A computer that connects to the Dash network. or allow them to advise each other about the rest of the network.

Overview Of P2P Protocol Control And Advisory MessagesOverview Of P2P Protocol Control And Advisory Messages

Note that almost none of the control messages are authenticated in any way, meaning they can contain incorrect or intentionally harmful information.

addr

The addr (IP address) message relays connection information for peers on the network. Each peer which wants to accept incoming connections creates an addr message providing its connection information and then sends that message to its peers unsolicited. Some of its peers send that information to their peers (also unsolicited), some of which further distribute it, allowing decentralized peer discovery for any program already on the network.

An addr message may also be sent in response to a getaddr message.

BytesNameData TypeDescription
VariesIP address countcompactSize uintThe number of IP address entries up to a maximum of 1,000.
VariesIP addressesnetwork IP addressIP address entries. See the table below for the format of a Dash network IP address.

Each encapsulated network IP address currently uses the following structure:

BytesNameData TypeDescription
4timeuint32Added in protocol version 31402.

A time in Unix epoch time format. Nodes advertising their own IP address set this to the current time. Nodes advertising IP addresses they've connected to set this to the last time they connected to that node. Other nodes just relaying the IP address should not change the time. Nodes can use the time field to avoid relaying old addr messages.

Malicious nodes may change times or even set them in the future.
8servicesuint64_tThe services the node advertised in its version message.
16IP addresscharIPv6 address in big endian byte order. IPv4 addresses can be provided as IPv4-mapped IPv6 addresses
2portuint16_tPort number in big endian byte order. Note that Dash Core will only connect to nodes with non-standard port numbers as a last resort for finding peers. This is to prevent anyone from trying to use the network to disrupt non-Dash services that run on other ports.

The following annotated hexdump shows part of an addr message. (The message headermessage header - The four header fields prefixed to all messages on the Dash P2P network. has been omitted and the actual IP address has been replaced with a RFC5737 reserved IP address.)

fde803 ............................. Address count: 1000

d91f4854 ........................... Epoch time: 1414012889
0100000000000000 ................... Service bits: 01 (network node)
00000000000000000000ffffc0000233 ... IP Address: ::ffff:192.0.2.51
208d ............................... Port: 8333

[...] .............................. (999 more addresses omitted)

filteradd

Added in protocol version 70001 as described by BIP37.

The filteradd message tells the receiving peerpeer - A computer that connects to the Dash network. to add a single element to a previously-set bloom filterbloom filter - A filter used primarily by SPV clients to request only matching transactions and merkle blocks from full nodes., such as a new public keypublic key - The public portion of a keypair which can be used to verify signatures made with the private portion of the keypair.. The element is sent directly to the receiving peer; the peer then uses the parameters set in the filterload message to add the element to the bloom filter.

Because the element is sent directly to the receiving peer, there is no obfuscation of the element and none of the plausible-deniability privacy provided by the bloom filter. Clients that want to maintain greater privacy should recalculate the bloom filter themselves and send a new filterload message with the recalculated bloom filter.

BytesNameData TypeDescription
Varieselement bytescompactSize uintThe number of bytes in the following element field.
Varieselementuint8_t[]The element to add to the current filter. Maximum of 520 bytes, which is the maximum size of an element which can be pushed onto the stack in a pubkey or signature script. Elements must be sent in the byte order they would use when appearing in a raw transaction; for example, hashes should be sent in internal byte order.

Note: a filteradd message will not be accepted unless a filter was previously set with the filterload message.

The annotated hexdump below shows a filteradd message adding a TXIDTXID - An identifier used to uniquely identify a particular transaction; specifically, the sha256d hash of the transaction.. (The message header has been omitted.) This TXID appears in the same block used for the example hexdump in the merkleblock message; if that merkleblock message is re-sent after sending this filteradd message, six hashes are returned instead of four.

20 ................................. Element bytes: 32
fdacf9b3eb077412e7a968d2e4f11b9a
9dee312d666187ed77ee7d26af16cb0b ... Element (A TXID)

filterclear

Added in protocol version 70001 as described by BIP37.

The filterclear message tells the receiving peerpeer - A computer that connects to the Dash network. to remove a previously-set bloom filterbloom filter - A filter used primarily by SPV clients to request only matching transactions and merkle blocks from full nodes.. This also undoes the effect of setting the relay field in the version message to 0, allowing unfiltered access to inv messages announcing new transactions.

Dash Core does not require a filterclear message before a replacement filter is loaded with filterload. It also doesn't require a filterload message before a filterclear message.

There is no payload in a filterclear message. See the message header section for an example of a message without a payload.

filterload

Added in protocol version 70001 as described by BIP37.

The filterload message tells the receiving peerpeer - A computer that connects to the Dash network. to filter all relayed transactions and requested merkle blocksmerkle blocks - A partial merkle tree connecting transactions matching a bloom filter to the merkle root of a block. through the provided filter. This allows clients to receive transactions relevant to their walletwallet - Software that stores private keys and monitors the block chain (sometimes as a client of a server that does the processing) to allow users to spend and receive duffs. plus a configurable rate of false positive transactions which can provide plausible-deniability privacy.

BytesNameData TypeDescription
VariesnFilterBytescompactSize uintNumber of bytes in the following filter bit field.
Variesfilteruint8_t[]A bit field of arbitrary byte-aligned size. The maximum size is 36,000 bytes.
4nHashFuncsuint32_tThe number of hash functions to use in this filter. The maximum value allowed in this field is 50.
4nTweakuint32_tAn arbitrary value to add to the seed value in the hash function used by the bloom filter.
1nFlagsuint8_tA set of flags that control how outpoints corresponding to a matched pubkey script are added to the filter. See the table in the Updating A Bloom Filter subsection below.

The annotated hexdump below shows a filterload message. (The message header has been omitted.) For an example of how this payload was created, see the filterload example.

02 ......... Filter bytes: 2
b50f ....... Filter: 1010 1101 1111 0000
0b000000 ... nHashFuncs: 11
00000000 ... nTweak: 0/none
00 ......... nFlags: BLOOM_UPDATE_NONE

Initializing A Bloom Filter

Filters have two core parameters: the size of the bit field and the number of hash functions to run against each data element. The following formulas from BIP37 will allow you to automatically select appropriate values based on the number of elements you plan to insert into the filter (n) and the false positive rate (p) you desire to maintain plausible deniability.

  • Size of the bit field in bytes (nFilterBytes), up to a maximum of 36,000: (-1 / log(2)**2 * n * log(p)) / 8

  • Hash functions to use (nHashFuncs), up to a maximum of 50:
    nFilterBytes * 8 / n * log(2)

Note that the filter matches parts of transactions (transaction elements), so the false positive rate is relative to the number of elements checked---not the number of transactions checked. Each normal transaction has a minimum of four matchable elements (described in the comparison subsection below), so a filter with a false-positive rate of 1 percent will match about 4 percent of all transactions at a minimum.

According to BIP37, the formulas and limits described above provide support for bloom filters containing 20,000 items with a false positive rate of less than 0.1 percent or 10,000 items with a false positive rate of less than 0.0001 percent.

Once the size of the bit field is known, the bit field should be initialized as all zeroes.

Populating A Bloom Filter

The bloom filter is populated using between 1 and 50 unique hash functions (the number specified per filter by the nHashFuncs field). Instead of using up to 50 different hash function implementations, a single implementation is used with a unique seed value for each function.

The seed is nHashNum * 0xfba4c795 + nTweak as a uint32_t, where the values are:

  • nHashNum is the sequence number for this hash function, starting at 0 for the first hash iteration and increasing up to the value of the nHashFuncs field (minus one) for the last hash iteration.

  • 0xfba4c795 is a constant optimized to create large differences in the seed for different values of nHashNum.

  • nTweak is a per-filter constant set by the client to require the use of an arbitrary set of hash functions.

If the seed resulting from the formula above is larger than four bytes, it must be truncated to its four most significant bytes (for example, 0x8967452301 & 0xffffffff โ†’ 0x67452301).

The actual hash function implementation used is the 32-bit Murmur3 hash function.

๐Ÿšง

Murmer3 Version

Warning: the Murmur3 hash function has separate 32-bit and 64-bit versions that produce different results for the same inputinput - An input in a transaction which contains three fields: an outpoint, a signature script, and a sequence number. The outpoint references a previous output and the signature script allows spending it.. Only the 32-bit Murmur3 version is used with Dash bloom filters.

The data to be hashed can be any transaction element which the bloom filter can match. See the next subsection for the list of transaction elements checked against the filter. The largest element which can be matched is a script data push of 520 bytes, so the data should never exceed 520 bytes.

The example below from Dash Core bloom.cpp combines all the steps above to create the hash function template. The seed is the first parameter; the data to be hashed is the second parameter. The result is a uint32_t modulo the size of the bit field in bits.

MurmurHash3(nHashNum * 0xFBA4C795 + nTweak, vDataToHash) % (vData.size() * 8)

Each data element to be added to the filter is hashed by nHashFuncs number of hash functions. Each time a hash function is run, the result will be the index number (nIndex) of a bit in the bit field. That bit must be set to 1. For example if the filter bit field was 00000000 and the result is 5, the revised filter bit field is 00000100 (the first bit is bit 0).

It is expected that sometimes the same index number will be returned more than once when populating the bit field; this does not affect the algorithm---after a bit is set to 1, it is never changed back to 0.

After all data elements have been added to the filter, each set of eight bits is converted into a little-endian byte. These bytes are the value of the filter field.

Comparing Transaction Elements To A Bloom Filter

To compare an arbitrary data element against the bloom filter, it is hashed using the same parameters used to create the bloom filter. Specifically, it is hashed nHashFuncs times, each time using the same
nTweak provided in the filter, and the resulting outputoutput - An output in a transaction which contains two fields: a value field for transferring zero or more duffs and a pubkey script for indicating what conditions must be fulfilled for those duffs to be further spent. is modulo the size of the bit field provided in the filter field. After each hash is performed, the filter is checked to see if the bit at that indexed location is set. For example if the result of a hash is 5 and the filter is 01001110, the bit is considered set.

If the result of every hash points to a set bit, the filter matches. If any of the results points to an unset bit, the filter does not match.

The following transaction elements are compared against bloom filters. All elements will be hashed in the byte order used in blocksblocks - One or more transactions prefaced by a block header and protected by proof of work. Blocks are the data stored on the block chain. (for example, TXIDsTXIDs - An identifier used to uniquely identify a particular transaction; specifically, the sha256d hash of the transaction. will be in internal byte orderinternal byte order - The standard order in which hash digests are displayed as strings---the same format used in serialized blocks and transactions.).

  • TXIDs: the transaction's SHA256(SHA256()) hash.

  • Outpoints: each 36-byte outpointoutpoint - The data structure used to refer to a particular transaction output, consisting of a 32-byte TXID and a 4-byte output index number (vout). used this transaction's input section is individually compared to the filter.

  • Signature Script Data: each element pushed onto the stack by a data-pushing opcodedata-pushing opcode - Any opcode from 0x01 to 0x4e which pushes data on to the script evaluation stack. in a signature scriptsignature script - Data generated by a spender which is almost always used as variables to satisfy a pubkey script. Signature Scripts are called scriptSig in code. from this transaction is individually compared to the filter. This includes data elements present in P2SH redeem scriptredeem script - A script similar in function to a pubkey script. One copy of it is hashed to create a P2SH address (used in an actual pubkey script) and another copy is placed in the spending signature script to enforce its conditions. when they are being spent.

  • PubKey Script Data: each element pushed onto the the stack by a data-pushing opcode in any pubkey scriptpubkey script - A script included in outputs which sets the conditions that must be fulfilled for those duffs to be spent. Data for fulfilling the conditions can be provided in a signature script. Pubkey Scripts are called a scriptPubKey in code. from this transaction is individually compared to the filter. (If a pubkey script element matches the filter, the filter will be immediately updated if the BLOOM_UPDATE_ALL flag was set; if the pubkey script is in the P2PKH format and matches the filter, the filter will be immediately updated if the BLOOM_UPDATE_P2PUBKEY_ONLY flag was set. See the subsection below for details.)

As of Dash Core 0.14.0, elements in the extra payload section of DIP2-based special transactionsspecial transactions - Special Transactions provide a way to include non-financial, consensus-assisting metadata (e.g. masternode lists) on-chain. are also compared against bloom filters.

The following annotated hexdump of a transaction is from the raw transaction format section; the elements which would be checked by the filter are emphasized in bold. Note that this transaction's TXID (01000000017b1eab[...]) would also be checked, and that the outpoint TXID and index number below would be checked as a single 36-byte element.

01000000 ................................... Version

01 ......................................... Number of inputs
|
| 

Updating A Bloom Filter

Clients will often want to track inputsinputs - An input in a transaction which contains three fields: an outpoint, a signature script, and a sequence number. The outpoint references a previous output and the signature script allows spending it. that spend outputsoutputs - An output in a transaction which contains two fields: a value field for transferring zero or more duffs and a pubkey script for indicating what conditions must be fulfilled for those duffs to be further spent. (outpoints) relevant to their wallet, so the filterload field nFlags can be set to allow the filtering nodenode - A computer that connects to the Dash network. to update the filter when a match is found. When the filtering node sees a pubkey scriptpubkey script - A script included in outputs which sets the conditions that must be fulfilled for those duffs to be spent. Data for fulfilling the conditions can be provided in a signature script. Pubkey Scripts are called a scriptPubKey in code. that pays a pubkey, addressaddress - A 20-byte hash formatted using base58check to produce either a P2PKH or P2SH Dash address. Currently the most common way users exchange payment information., or other data element matching the filter, the filtering node immediately updates the filter with the outpointoutpoint - The data structure used to refer to a particular transaction output, consisting of a 32-byte TXID and a 4-byte output index number (vout). corresponding to that pubkey script.

Automatically Updating Bloom FiltersAutomatically Updating Bloom Filters

If an input later spends that outpoint, the filter will match it, allowing the filtering node to tell the client that one of its transaction outputs has been spent.

The nFlags field has three allowed values:

ValueNameDescription
0BLOOM_UPDATE_NONEThe filtering node should not update the filter.
1BLOOM_UPDATE_ALLIf the filter matches any data element in a pubkey script, the corresponding outpoint is added to the filter.
2BLOOM_UPDATE_P2PUBKEY_ONLYIf the filter matches any data element in a pubkey script and that script is either a P2PKH or non-P2SH pay-to-multisig script, the corresponding outpoint is added to the filter.

In addition, because the filter size stays the same even though additional elements are being added to it, the false positive rate increases. Each false positive can result in another element being added to the filter, creating a feedback loop that can (after a certain point) make the filter useless. For this reason, clients using automatic filter updates need to monitor the actual false positive rate and send a new filter when the rate gets too high.

getaddr

The getaddr message requests an addr message from the receiving nodenode - A computer that connects to the Dash network., preferably one with lots of IP addresses of other receiving nodes. The transmitting node can use those IP addresses to quickly update its database of available nodes rather than waiting for unsolicited addr messages to arrive over time.

There is no payload in a getaddr message. See the message header section for an example of a message without a payload.

getsporks

The getsporks message requests spork messages from the receiving node.

There is no payload in a getsporks message. See the message header section for an example of a message without a payload.

ping

The ping message helps confirm that the receiving peerpeer - A computer that connects to the Dash network. is still connected. If a TCP/IP error is encountered when sending the ping message (such as a connection timeout), the transmitting node can assume that the receiving node is disconnected. The response to a ping message is the pong message.

Before protocol version 60000, the ping message had no payload. As of protocol version 60001 and all later versions, the message includes a single field, the nonce.

BytesNameData TypeDescription
8nonceuint64_tAdded in protocol version 60001 as described by BIP31.

Random nonce assigned to this ping message. The responding pong message will include this nonce to identify the ping message to which it is replying.

The annotated hexdump below shows a ping message. (The message header has been omitted.)

0094102111e2af4d ... Nonce

pong

Added in protocol version 60001 as described by BIP31.

The pong message replies to a ping message, proving to the pinging nodenode - A computer that connects to the Dash network. that the ponging node is still alive. Dash Core will, by default, disconnect from any clients which have not responded to a ping message within 20 minutes.

To allow nodes to keep track of latency, the pong message sends back the same nonce received in the ping message it is replying to.

The format of the pong message is identical to the ping message; only the message header differs.

reject

Added in protocol version 70002 as described by BIP61.

The reject message informs the receiving nodenode - A computer that connects to the Dash network. that one of its previous messages has been rejected.

BytesNameData TypeDescription
Variesmessage bytescompactSize uintThe number of bytes in the following message field.
VariesmessagestringThe type of message rejected as ASCII text without null padding. For example: "tx", "block", or "version".
1codecharThe reject message code. See the table below.
Variesreason bytescompactSize uintThe number of bytes in the following reason field. May be 0x00 if a text reason isn't provided.
VariesreasonstringThe reason for the rejection in ASCII text. This should not be displayed to the user; it is only for debugging purposes.
Variesextra datavariesOptional additional data provided with the rejection. For example, most rejections of tx messages or block messages include the hash of the rejected transaction or block header. See the code table below.

The following table lists message reject codes. Codes are tied to the type of message they reply to; for example there is a 0x10 reject code for transactions and a 0x10 reject code for blocks.

CodeIn Reply ToExtra BytesExtra TypeDescription
0x01any message0N/AMessage could not be decoded. Be careful of reject message feedback loops where two peers each don't understand each other's reject messages and so keep sending them back and forth forever.
0x10block message32char[32]Block is invalid for some reason (invalid proof-of-work, invalid signature, etc). Extra data may include the rejected block's header hash.
0x10tx message32char[32]Transaction is invalid for some reason (invalid signature, output value greater than input, etc.). Extra data may include the rejected transaction's TXID.
0x10ix message32char[32]InstantSend transaction is invalid for some reason (invalid tx lock request, conflicting tx lock request, etc.). Extra data may include the rejected transaction's TXID.
0x11block message32char[32]The block uses a version that is no longer supported. Extra data may include the rejected block's header hash.
0x11version message0N/AConnecting node is using a protocol version that the rejecting node considers obsolete and unsupported.
0x11dsa message0N/AConnecting node is using a PrivateSend protocol version that the rejecting node considers obsolete and unsupported.
0x11dsi message0N/AConnecting node is using a PrivateSend protocol version that the rejecting node considers obsolete and unsupported.
0x11dsc message0N/AConnecting node is using a PrivateSend protocol version that the rejecting node considers obsolete and unsupported.
0x11dsf message0N/AConnecting node is using a PrivateSend protocol version that the rejecting node considers obsolete and unsupported.
0x11dsq message0N/AConnecting node is using a PrivateSend protocol version that the rejecting node considers obsolete and unsupported.
0x11dssu message0N/AConnecting node is using a PrivateSend protocol version that the rejecting node considers obsolete and unsupported.
0x11govsync message0N/AConnecting node is using a governance protocol version that the rejecting node considers obsolete and unsupported.
0x11govobj message0N/AConnecting node is using a governance protocol version that the rejecting node considers obsolete and unsupported.
0x11govobjvote message0N/AConnecting node is using a governance protocol version that the rejecting node considers obsolete and unsupported.
0x11mnget message0N/AConnecting node is using a masternode payment protocol version that the rejecting node considers obsolete and unsupported.
0x11mnw message0N/AConnecting node is using a masternode payment protocol version that the rejecting node considers obsolete and unsupported.
0x11txlvote message0N/AConnecting node is using an InstantSend protocol version that the rejecting node considers obsolete and unsupported.
0x12tx message32char[32]Duplicate input spend (double spend): the rejected transaction spends the same input as a previously-received transaction. Extra data may include the rejected transaction's TXID.
0x12version message0N/AMore than one version message received in this connection.
0x40tx message32char[32]The transaction will not be mined or relayed because the rejecting node considers it non-standard---a transaction type or version unknown by the server. Extra data may include the rejected transaction's TXID.
0x41tx message32char[32]One or more output amounts are below the dust threshold. Extra data may include the rejected transaction's TXID.
0x42tx messagechar[32]The transaction did not have a large enough fee or priority to be relayed or mined. Extra data may include the rejected transaction's TXID.
0x43block message32char[32]The block belongs to a block chain which is not the same block chain as provided by a compiled-in checkpoint. Extra data may include the rejected block's header hash.

Reject Codes

CodeDescription
0x01Malformed
0x10Invalid
0x11Obsolete
0x12Duplicate
0x40Non-standard
0x41Dust
0x42Insufficient fee
0x43Checkpoint

The annotated hexdump below shows a reject message. (The message header has been omitted.)

02 ................................. Number of bytes in message: 2
7478 ............................... Type of message rejected: tx
12 ................................. Reject code: 0x12 (duplicate)
15 ................................. Number of bytes in reason: 21
6261642d74786e732d696e707574732d
7370656e74 ......................... Reason: bad-txns-inputs-spent
394715fcab51093be7bfca5a31005972
947baf86a31017939575fb2354222821 ... TXID

sendcmpct

Added in protocol version 70209 of Dash Core as described by BIP152

The sendcmpct message tells the receiving peerpeer - A computer that connects to the Dash network. whether or not to announce new blocksblocks - One or more transactions prefaced by a block header and protected by proof of work. Blocks are the data stored on the block chain. using a cmpctblock message. It also sends the compact block protocol version it supports. The sendcmpct message is defined as a message containing a 1-byte integer followed by a 8-byte integer. The first integer is interpreted as a boolean and should have a value of either 1 or 0. The second integer is be interpreted as a little-endian version number.

Upon receipt of a sendcmpct message with the first and second integers set to 1, the nodenode - A computer that connects to the Dash network. should announce new blocks by sending a cmpctblock message.

Upon receipt of a sendcmpct message with the first integer set to 0, the node shouldn't announce new blocks by sending a cmpctblock message, but instead announce new blocks by sending invs or headersheaders - An 80-byte header belonging to a single block which is hashed repeatedly to create proof of work., as defined by BIP130.

Upon receipt of a sendcmpct message with the second integer set to something other than 1, nodes should treat the peer as if they had not received the message (as it indicates the peer will provide an unexpected encoding in cmpctblock messages, and/or other, messages). This allows future versions to send duplicate sendcmpct messages with different versions as a part of a version handshake.

Nodes should check for a protocol version of >= 70209 before sending sendcmpct messages. Nodes shouldn't send a request for a MSG_CMPCT_BLOCK object to a peer before having received a sendcmpct message from that peer. Nodes shouldn't request a MSG_CMPCT_BLOCK object before having sent all sendcmpct messages to that peer which they intend to send, as the peer cannot know what protocol version to use in the response.

The structure of a sendcmpct message is defined below.

BytesNameData TypeDescription
1announcebool0 - Announce blocks via headers message or inv message
1 - Announce blocks via cmpctblock message
8versionuint64_tThe compact block protocol version number

The annotated hexdump below shows a sendcmpct message. (The message header has been omitted.)

01 ................................. Block announce type: Compact Blocks
0100000000000000 ................... Compact block version: 1

senddsq

Added in protocol version 70214 of Dash Core

The senddsq message is used to notify a peerpeer - A computer that connects to the Dash network. whether or not to send dsq messages. This allows clients that are not interested in PrivateSend mixing (e.g. mobile walletwallet - Software that stores private keys and monitors the block chain (sometimes as a client of a server that does the processing) to allow users to spend and receive duffs.) to minimize data usage.

BytesNameData typeDescription
1fSendDSQueuebool0 - Notify peer to not send any dsq messages
1 - Notify peer to send all dsq messages

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

01 ................................. PrivateSend participation: Enabled (1)

sendheaders

The sendheaders message tells the receiving peerpeer - A computer that connects to the Dash network. to send new blockblock - One or more transactions prefaced by a block header and protected by proof of work. Blocks are the data stored on the block chain. announcements using a headers message rather than an inv message.

There is no payload in a sendheaders message. See the message header section for an example of a message without a payload.

spork

Sporks are a mechanism by which updated code is released to the network, but not immediately made active (or โ€œenforcedโ€). Enforcement of the updated code can be activated remotely. Should problems arise, the code can be deactivated in the same manner, without the need for a network-wide rollback or client update.

A spork message may be sent in response to a getsporks message.

The spork message tells the receiving peer the status of the spork defined by the SporkID field. Upon receiving a sporkspork - A spork is a mechanism unique to Dash used to safely deploy new features to the network through network-level variables to avoid the risk of unintended network forking during upgrades. message, the client must verify the signaturesignature - A value related to a public key which could only have reasonably been created by someone who has the private key that created that public key. Used in Dash to authorize spending duffs previously sent to a public key. before accepting the spork message as valid.

BytesNameData typeRequiredDescription
4nSporkIDintRequiredID assigned in spork.h
8nValueint64_tRequiredValue assigned to spork
Default (disabled): 4000000000
8nTimeSignedint64_tRequiredTime the spork value was signed
66vchSigchar[]RequiredLength (1 byte) + Signature (65 bytes)

Active Sporks (per src/spork.h)

Spork IDNum.NameDescription
100012INSTANTSEND_ENABLEDTurns on and off InstantSend network wide
100023INSTANTSEND_BLOCK_
FILTERING
Turns on and off InstantSend block filtering
100089SUPERBLOCKS_ENABLEDSuperblocks are enabled (10% of the block reward allocated to fund the dash treasury for funding approved proposals)
1001617SPORK_17_QUORUM_DKG_
ENABLED
Enable long-living masternode quorum (LLMQ) distributed key generation (DKG). When enabled, simple PoSe scoring and banning is active as well.
1001819SPORK_19_CHAINLOCKS_
ENABLED
Enable LLMQ-based ChainLocks.
1002021SPORK_21_QUORUM_ALL_
CONNECTED
Added in Dash Core 0.16.0
Enable connections between all masternodes in a quorum to optimize the signature recovery process. Also enforces PoSe requirements for masternodes to support a minimum protocol version and maintain open ports.
1002122SPORK_22_PS_MORE_
PARTICIPANTS
Added in Dash Core 0.16.0
Increase the maximum number of participants in PrivateSend mixing sessions.

๐Ÿ“˜

Spork 21 Values

Spork 21 supports two different enabled values:

  • 0 - Connections established between each masternode in a quorum (regardless of quorum size)
  • 1 - Connections established between each masternode in LLMQ_50_60 quorums only

Removed Sporks
The following sporks were used in the past but are no longer necessary and have been removed.

๐Ÿ“˜

Spork 6

Since spork 6 was never enabled on mainnet, it was removed in Dash Core 0.16.0. The associated logic was hardened in PR 3662 to support testnet (where it is enabled). If testnet is reset at some point in the future, the remaining logic will be removed.

Spork IDNum.NameDescription
100045INSTANTSEND_MAX_VALUERemoved in Dash Core 0.15.0.
Controls the max value for an InstantSend transaction (currently 2000 DASH)
100056NEW_SIGSRemoved in Dash Core 0.16.0.
Turns on and off new signature format for Dash-specific messages
100078MASTERNODE_PAYMENT_
ENFORCEMENT
Removed in Dash Core 0.14.0.
Requires masternodes to be paid by miners when blocks are processed
1000910MASTERNODE_PAY_
UPDATED_NODES
Removed in Dash Core 0.14.0.
Only current protocol version masternode's will be paid (not older nodes)
1001112RECONSIDER_BLOCKSRemoved in Dash Core 0.15.0.
Forces reindex of a specified number of blocks to recover from unintentional network forks
1001213OLD_SUPERBLOCK_FLAGRemoved in Dash Core 0.12.3.
No network function since block 614820
1001314REQUIRE_SENTINEL_FLAGRemoved in Dash Core 0.14.0.
Only masternode's running sentinel will be paid
1001415DETERMINISTIC_MNS_
ENABLED
Removed in Dash Core 0.16.0.
Deterministic masternode lists are enabled
1001516INSTANTSEND_AUTOLOCKSRemoved in Dash Core 0.16.0.
Automatic InstantSend for transactions with <=4 inputs (also eliminates the special InstantSend fee requirement for these transactions)
1001718QUORUM_DEBUG_ENABLEDRemoved in Dash Core 0.14.0.

Temporarily used on Testnet only quorum debugging.
1001920SPORK_20_INSTANTSEND_
LLMQ_BASED
Removed in Dash Core 0.16.0.
Enable LLMQ-based InstantSend.

To verify vchSig, compare the hard-coded spork public key (strSporkPubKey from src/chainparams.cpp) with the public key recovered from the spork message's hash and vchSig value (implementation details for Dash Core can be found in CPubKey::RecoverCompact). The hash is a double SHA-256 hash of:

  • The spork magic message ("DarkCoin Signed Message:\n")
  • nSporkID + nValue + nTimeSigned
NetworkSpork Pubkey (wrapped)
Mainnet04549ac134f694c0243f503e8c8a9a986f5de6610049c40b07816809b0d1
d06a21b07be27b9bb555931773f62ba6cf35a25fd52f694d4e1106ccd237
a7bb899fdd
Testnet3046f78dcf911fbd61910136f7f0f8d90578f68d0b3ac973b5040fb7afb50
1b5939f39b108b0569dca71488f5bbf498d92e4d1194f6f941307ffd95f7
5e76869f0e
RegTestUndefined
Devnets046f78dcf911fbd61910136f7f0f8d90578f68d0b3ac973b5040fb7afb50
1b5939f39b108b0569dca71488f5bbf498d92e4d1194f6f941307ffd95f7
5e76869f0e

The following annotated hexdump shows a spork message.

11270000 .................................... Spork ID: Spork 2 InstantSend enabled (10001)
0000000000000000 ............................ Value (0)
2478da5900000000 ............................ Epoch time: 2017-10-08 19:10:28 UTC (1507489828)

41 .......................................... Signature length: 65

1b6762d3e70890b5cfaed5d1fd72121c
d32020c827a89f8128a00acd210f4ea4
1b36c26c3767f8a24f48663e189865ed
403ed1e850cdb4207cdd466419d9d183
45 .......................................... Masternode Signature

verack

The verack message acknowledges a previously-received version message, informing the connecting nodenode - A computer that connects to the Dash network. that it can begin to send other messages. The verack message has no payload; for an example of a message with no payload, see the message headers section.

version

The version message provides information about the transmitting nodenode - A computer that connects to the Dash network. to the receiving node at the beginning of a connection. Until both peerspeers - A computer that connects to the Dash network. have exchanged version messages, no other messages will be accepted.

If a version message is accepted, the receiving node should send a verack message---but no node should send a verack message before initializing its half of the connection by first sending a version message.

Protocol version 70214 added a masternodemasternode - A computer that provides second-tier Dash functionality (InstantSend, PrivateSend, decentralized governance). Masternodes are incentivized by receiving part of the block reward, but must hold 1000 Dash as collateral to prevent sybil attacks. authentication (challenge/response) system. Following the verack message, masternodes should send a mnauth message that signs the mnauth_challenge with their BLS operator key.

BytesNameData
Type
Required/
Optional
Description
4versionint32_tRequiredThe highest protocol version understood by the transmitting node. See the protocol version section.
8servicesuint64_tRequiredThe services supported by the transmitting node encoded as a bitfield. See the list of service codes below.
8timestampint64_tRequiredThe current Unix epoch time according to the transmitting node's clock. Because nodes will reject blocks with timestamps more than two hours in the future, this field can help other nodes to determine that their clock is wrong.
8addr_recv servicesuint64_tRequiredAdded in protocol version 106.

The services supported by the receiving node as perceived by the transmitting node. Same format as the 'services' field above. Dash Core will attempt to provide accurate information.
16addr_recv IP addresscharRequiredAdded in protocol version 106.

The IPv6 address of the receiving node as perceived by the transmitting node in big endian byte order. IPv4 addresses can be provided as IPv4-mapped IPv6 addresses. Dash Core will attempt to provide accurate information.
2addr_recv portuint16_tRequiredAdded in protocol version 106.

The port number of the receiving node as perceived by the transmitting node in big endian byte order.
8addr_trans servicesuint64_tRequiredThe services supported by the transmitting node. Should be identical to the 'services' field above.
16addr_trans IP addresscharRequiredThe IPv6 address of the transmitting node in big endian byte order. IPv4 addresses can be provided as IPv4-mapped IPv6 addresses. Set to ::ffff:127.0.0.1 if unknown.
2addr_trans portuint16_tRequiredThe port number of the transmitting node in big endian byte order.
8nonceuint64_tRequiredA random nonce which can help a node detect a connection to itself. If the nonce is 0, the nonce field is ignored. If the nonce is anything else, a node should terminate the connection on receipt of a version message with a nonce it previously sent.
Variesuser_agent bytescompactSize uintRequiredNumber of bytes in following user_agent field. If 0x00, no user agent field is sent.
Variesuser_agentstringRequired if user_agent bytes > 0Renamed in protocol version 60000.

User agent as defined by BIP14. Previously called subVer.

Dash Core limits the length to 256 characters.
4start_heightint32_tRequiredThe height of the transmitting node's best block chain or, in the case of an SPV client, best block header chain.
1relayboolOptionalAdded in protocol version 70001 as described by BIP37.

Transaction relay flag. If 0x00, no inv messages or tx messages announcing new transactions should be sent to this client until it sends a filterload message or filterclear message. If the relay field is not present or is set to 0x01, this node wants inv messages and tx messages announcing new transactions.
32mnauth_
challenge
uint256OptionalAdded in protocol version 70214

A challenge to be signed by the receiving masternode. The response is returned via a mnauth message following the verack message.

The following service identifiers have been assigned.

ValueNameDescription
0x00UnnamedThis node is not a full node. It may not be able to provide any data except for the transactions it originates.
0x01NODE_NETWORKThis is a full node and can be asked for full blocks. It should implement all protocol features available in its self-reported protocol version.
0x02NODE_GETUTXOThis node is capable of responding to the getutxo protocol request. Dash Core does not support this service.
0x04NODE_BLOOMThis node is capable and willing to handle bloom-filtered connections. Dash Core nodes used to support this by default, without advertising this bit, but no longer do as of protocol version 70201 (= NO_BLOOM_VERSION)
0x08NODE_XTHINThis node supports Xtreme Thinblocks. Dash Core does not support this service.
0x400NODE_NETWORK_LIMITEDThis is the same as NODE_NETWORK with the limitation of only serving the last 288 blocks. Not supported prior to Dash Core 0.16.0

The following annotated hexdump shows a version message. (The message header has been omitted and the actual IP addresses have been replaced with RFC5737 reserved IP addresses.)

46120100 .................................... Protocol version: 70214
0500000000000000 ............................ Services: NODE_NETWORK (1) + NODE_BLOOM (4)
9c10ad5c00000000 ............................ Epoch time: 1554845852

0100000000000000 ............................ Receiving node's services
00000000000000000000ffffc61b6409 ............ Receiving node's IPv6 address
270f ........................................ Receiving node's port number

0500000000000000 ............................ Transmitting node's services
00000000000000000000ffffcb0071c0 ............ Transmitting node's IPv6 address
270f ........................................ Transmitting node's port number

128035cbc97953f8 ............................ Nonce

12 .......................................... Bytes in user agent string: 18
2f4461736820436f72653a302e31322e312e352f..... User agent: /Dash Core:0.14.0/

851f0b00 .................................... Start height: 76944
01 .......................................... Relay flag: true

5dbb5d1baade6a9afa34db708f72c0dd
b5bd82b3656493484556689640a91357 ............ Masternode Auth. Challenge

Updated 3 months ago


What's Next

Data Messages

Control Messages


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