DOCUMENTATION

Each full node in the CICOIN network independently stores a block chain containing only blocks validated by that node. When several nodes all have the same blocks in their block chain, they are considered to be in consensus. The validation rules these nodes follow to maintain consensus are called consensus rules

A block of one or more new transactions is collected into the transaction data part of a block. Copies of each transaction are hashed, and the hashes are then paired, hashed, paired again, and hashed again until a single hash remains, the merkle root of a merkle tree.

The merkle root is stored in the block header. Each block also stores the hash of the previous block’s header, chaining the blocks together. This ensures a transaction cannot be modified without modifying the block that records it and all following blocks.

Transactions are also chained together. CICOIN wallet software gives the impression that coin are sent from and to wallets, but CICOINs really move from transaction to transaction. Each transaction spends the coin previously received in one or more earlier transactions, so the input of one transaction is the output of a previous transaction.

A single transaction can create multiple outputs, as would be the case when sending to multiple addresses, but each output of a particular transaction can only be used as an input once in the block chain. A

Outputs are tied to transaction identifiers (TXIDs), which are the hashes of signed transactions.

Because each output of a particular transaction can only be spent once, the outputs of all transactions included in the block chain can be categorized as either Unspent Transaction Outputs (UTXOs) or spent transaction outputs. For a payment to be valid, it must only use UTXOs as inputs.

TRANSACTIONS

OpCodes

• Various data pushing opcodes from 0x00 to 0x4e (1–78). These aren’t typically shown in examples, but they must be used to push signatures and public keys onto the stack. See the link below this list for a description.
• OP_TRUE/OP_1 (0x51) and OP_2 through OP_16 (0x52–0x60), which push the values 1 through 16 to the stack.
• OP_CHECKSIG consumes a signature and a full public key, and pushes true onto the stack if the transaction data specified by the SIGHASH flag was converted into the signature using the same ECDSA private key that generated the public key. Otherwise, it pushes false onto the stack.
• OP_DUP pushes a copy of the topmost stack item on to the stack.
• OP_HASH160 consumes the topmost item on the stack, computes the RIPEMD160(SHA256()) hash of that item, and pushes that hash onto the stack.
• OP_EQUAL consumes the top two items on the stack, compares them, and pushes true onto the stack if they are the same, false if not.
• OP_VERIFY consumes the topmost item on the stack. If that item is zero (false) it terminates the script in failure.
• OP_EQUALVERIFY runs OP_EQUAL and then OP_VERIFY in sequence.
• OP_CHECKMULTISIG consumes the value (n) at the top of the stack, consumes that many of the next stack levels (public keys), consumes the value (m) now at the top of the stack, and consumes that many of the next values (signatures) plus one extra value.The “one extra value” it consumes is the result of an off-by-one error in the CICOIN Core implementation. This value is not used, so signature scripts prefix the list of secp256k1 signatures with a single OP_0 (0x00). OP_CHECKMULTISIG compares the first signature against each public key until it finds an ECDSA match. Starting with the subsequent public key, it compares the second signature against each remaining public key until it finds an ECDSA match. The process is repeated until all signatures have been checked or not enough public keys remain to produce a successful result.Because public keys are not checked again if they fail any signature comparison, signatures must be placed in the signature script using the same order as their corresponding public keys were placed in the pubkey script or redeem script. See the OP_CHECKMULTISIG warning below for more details.
• OP_RETURN terminates the script in failure when executed.

Address Conversion

The hashes used in P2PKH and P2SH outputs are commonly encoded as CICOIN addresses. This is the procedure to encode those hashes and decode the addresses.

First, get your hash. For P2PKH, you RIPEMD-160(SHA256()) hash a ECDSA public key derived from your 256-bit ECDSA private key (random data). For P2SH, you RIPEMD-160(SHA256()) hash a redeem script serialized in the format used in raw transactions (described in a following sub-section).

CompactSize Unsigned Integers

The raw transaction format and several peer-to-peer network messages use a type of variable-length integer to indicate the number of bytes in a following piece of data.

CICOIN Core code and this document refers to these variable length integers as compactSize. Many other documents refer to them as var_int or varInt, but this risks conflation with other variable-length integer encodings—such as the CVarInt class used in CICOIN Core for serializing data to disk. Because it’s used in the transaction format, the format of compactSize unsigned integers is part of the consensus rules.

For numbers from 0 to 252, compactSize unsigned integers look like regular unsigned integers. For other numbers up to 0xffffffffffffffff, a byte is prefixed to the number to indicate its length—but otherwise the numbers look like regular unsigned integers in little-endian order.

ssss For example, the number 515 is encoded as 0xfd0302.

WALLET

Deterministic Wallet Formats

• Type 1: Single Chain Wallets
• Type 1 deterministic wallets are the simpler of the two, which can create a single series of keys from a single seed. A primary weakness is that if the seed is leaked, all funds are compromised, and wallet sharing is extremely limited.
• Type 2: Hierarchical Deterministic (HD) Wallets

For an overview of HD wallets, please see the developer guide section. For details, please see BIP32.

P2P NETWORK

BLOCK

The block message transmits a single serialized block in the format described in the serialized blocks section. See that section for an example hexdump. It can be sent for two different reasons:

1. GetData Response: Nodes will always send it in response to a getdata message that requests the block with an inventory type of MSG_BLOCK (provided the node has that block available for relay).
2. Unsolicited: Some miners will send unsolicited block messages broadcasting their newly-mined blocks to all of their peers. Many mining pools do the same thing, although some may be misconfigured to send the block from multiple nodes, possibly sending the same block to some peers more than once.

GetBlocks

The getblocks message requests an inv message that provides block header hashes starting from a particular point in the block chain. It allows a peer which has been disconnected or started for the first time to get the data it needs to request the blocks it hasn’t seen.

Peers which have been disconnected may have stale blocks in their locally-stored block chain, so the getblocks message allows the requesting peer to provide the receiving peer with multiple header hashes at various heights on their local chain. This allows the receiving peer to find, within that list, the last header hash they had in common and reply with all subsequent header hashes.

Note: the receiving peer itself may respond with an inv message containing header hashes of stale blocks. It is up to the requesting peer to poll all of its peers to find the best block chain.

If the receiving peer does not find a common header hash within the list, it will assume the last common block was the genesis block (block zero), so it will reply with in inv message containing header hashes starting with block one (the first block after the genesis block).

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

71110100 ........................... Protocol version: 70001
02 ................................. Hash count: 2

d39f608a7775b537729884d4e6633bb2
105e55a16a14d31b0000000000000000 ... Hash #1

5c3e6403d40837110a2e8afb602b1c01
714bda7ce23bea0a0000000000000000 ... Hash #2

00000000000000000000000000000000
00000000000000000000000000000000 ... Stop hash

GetData

The getdata message requests one or more data objects from another node. The objects are requested by an inventory, which the requesting node typically received previously by way of an inv message.

The response to a getdata message can be a tx message, block message, merkleblock message, cmpctblock message, or notfound message.

This message cannot be used to request arbitrary data, such as historic transactions no longer in the memory pool or relay set. Full nodes may not even be able to provide older blocks if they’ve pruned old transactions from their block database. For this reason, the getdata message should usually only be used to request data from a node which previously advertised it had that data by sending an inv message.

The format and maximum size limitations of the getdata message are identical to the inv message; only the message header differs.

GetHeaders

The getheaders message requests a headers message that provides block headers starting from a particular point in the block chain. It allows a peer which has been disconnected or started for the first time to get the headers it hasn’t seen yet.

The getheaders message is nearly identical to the getblocks message, with one minor difference: the inv reply to the getblocks message will include no more than 500 block header hashes; the headers reply to the getheaders message will include as many as 2,000 block headers.

Headers

The headers message sends block headers to a node which previously requested certain headers with a getheaders message. A headers message can be empty.

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

01 ................................. Header count: 1

02000000 ........................... Block version: 2
b6ff0b1b1680a2862a30ca44d346d9e8
910d334beb48ca0c0000000000000000 ... Hash of previous block's header
9d10aa52ee949386ca9385695f04ede2
70dda20810decd12bc9b048aaab31471 ... Merkle root
24d95a54 ........................... Unix time: 1415239972
30c31b18 ........................... Target (bits)
fe9f0864 ........................... Nonce

00 ................................. Transaction count (0x00)

Inv

The inv message (inventory message) transmits one or more inventories of objects known to the transmitting peer. It can be sent unsolicited to announce new transactions or blocks, or it can be sent in reply to a getblocks message or mempool message.

The receiving peer can compare the inventories from an inv message against the inventories it has already seen, and then use a follow-up message to request unseen objects.

MemPool

The mempool message requests the TXIDs of transactions that the receiving node has verified as valid but which have not yet appeared in a block. That is, transactions which are in the receiving node’s memory pool. The response to the mempool message is one or more inv messages containing the TXIDs in the usual inventory format.

Sending the mempool message is mostly useful when a program first connects to the network. Full nodes can use it to quickly gather most or all of the unconfirmed transactions available on the network; this is especially useful for miners trying to gather transactions for their transaction fees. SPV clients can set a filter before sending a mempool to only receive transactions that match that filter; this allows a recently-started client to get most or all unconfirmed transactions related to its wallet.

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

MerkleBlock

The merkleblock message is a reply to a getdata message which requested a block using the inventory type MSG_MERKLEBLOCK. It is only part of the reply: if any matching transactions are found, they will be sent separately as tx messages.

If a filter has been previously set with the filterload message, the merkleblock message will contain the TXIDs of any transactions in the requested block that matched the filter, as well as any parts of the block’s merkle tree necessary to connect those transactions to the block header’s merkle root. The message also contains a complete copy of the block header to allow the client to hash it and confirm its proof of work.

The annotated hexdump below shows a merkleblock message which corresponds to the examples below. (The message header has been omitted.)

01000000 ........................... Block version: 1
82bb869cf3a793432a66e826e05a6fc3
7469f8efb7421dc88067010000000000 ... Hash of previous block's header
7f16c5962e8bd963659c793ce370d95f
093bc7e367117b3c30c1f8fdd0d97287 ... Merkle root
76381b4d ........................... Time: 1293629558
4c86041b ........................... nBits: 0x04864c * 256**(0x1b-3)
554b8529 ........................... Nonce

07000000 ........................... Transaction count: 7
04 ................................. Hash count: 4

3612262624047ee87660be1a707519a4
43b1c1ce3d248cbfc6c15870f6c5daa2 ... Hash #1
019f5b01d4195ecbc9398fbf3c3b1fa9
bb3183301d7a1fb3bd174fcfa40a2b65 ... Hash #2
41ed70551dd7e841883ab8f0b16bf041
76b7d1480e4f0af9f3d4c3595768d068 ... Hash #3
20d2a7bc994987302e5b1ac80fc425fe
25f8b63169ea78e68fbaaefa59379bbf ... Hash #4

01 ................................. Flag bytes: 1
1d ................................. Flags: 1 0 1 1 1 0 0 0

Note: when fully decoded, the above merkleblock message provided the TXID for a single transaction that matched the filter. In the network traffic dump this output was taken from, the full transaction belonging to that TXID was sent immediately after the merkleblock message as a tx message.

Parsing A MerkleBlock Message

As seen in the annotated hexdump above, the merkleblock message provides three special data types: a transaction count, a list of hashes, and a list of one-bit flags.

You can use the transaction count to construct an empty merkle tree. We’ll call each entry in the tree a node; on the bottom are TXID nodes—the hashes for these nodes are TXIDs; the remaining nodes (including the merkle root) are non-TXID nodes—they may actually have the same hash as a TXID, but we treat them differently.

Keep the hashes and flags in the order they appear in the merkleblock message. When we say “next flag” or “next hash”, we mean the next flag or hash on the list, even if it’s the first one we’ve used so far.

Start with the merkle root node and the first flag. The table below describes how to evaluate a flag based on whether the node being processed is a TXID node or a non-TXID node. Once you apply a flag to a node, never apply another flag to that same node or reuse that same flag again.

Any time you begin processing a node for the first time, evaluate the next flag. Never use a flag at any other time.

When processing a child node, you may need to process its children (the grandchildren of the original node) or further-descended nodes before returning to the parent node. This is expected—keep processing depth first until you reach a TXID node or a non-TXID node with a flag of 0.

After you process a TXID node or a non-TXID node with a flag of 0, stop processing flags and begin to ascend the tree. As you ascend, compute the hash of any nodes for which you now have both child hashes or for which you now have the sole child hash. See the merkle tree section for hashing instructions. If you reach a node where only the left hash is known, descend into its right child (if present) and further descendants as necessary.

However, if you find a node whose left and right children both have the same hash, fail. This is related to CVE-2012-2459.

Continue descending and ascending until you have enough information to obtain the hash of the merkle root node. If you run out of flags or hashes before that condition is reached, fail. Then perform the following checks (order doesn’t matter):

• Fail if there are unused hashes in the hashes list.
• Fail if there are unused flag bits—except for the minimum number of bits necessary to pad up to the next full byte.
• Fail if the hash of the merkle root node is not identical to the merkle root in the block header.
• Fail if the block header is invalid. Remember to ensure that the hash of the header is less than or equal to the target threshold encoded by the nBits header field. Your program should also, of course, attempt to ensure the header belongs to the best block chain and that the user knows how many confirmations this block has.

For a detailed example of parsing a merkleblock message, please see the corresponding merkle block examples section.

Creating A MerkleBlock Message

It’s easier to understand how to create a merkleblock message after you understand how to parse an already-created message, so we recommend you read the parsing section above first.

Create a complete merkle tree with TXIDs on the bottom row and all the other hashes calculated up to the merkle root on the top row. For each transaction that matches the filter, track its TXID node and all of its ancestor nodes.

Start processing the tree with the merkle root node. The table below describes how to process both TXID nodes and non-TXID nodes based on whether the node is a match, a match ancestor, or neither a match nor a match ancestor.

Any time you begin processing a node for the first time, a flag should be appended to the flag list. Never put a flag on the list at any other time, except when processing is complete to pad out the flag list to a byte boundary.

When processing a child node, you may need to process its children (the grandchildren of the original node) or further-descended nodes before returning to the parent node. This is expected—keep processing depth first until you reach a TXID node or a node which is neither a TXID nor a match ancestor.

After you process a TXID node or a node which is neither a TXID nor a match ancestor, stop processing and begin to ascend the tree until you find a node with a right child you haven’t processed yet. Descend into that right child and process it.

After you fully process the merkle root node according to the instructions in the table above, processing is complete. Pad your flag list to a byte boundary and construct the merkleblock message using the template near the beginning of this subsection.

CmpctBlock

Version 1 compact blocks are pre-segwit (txids) Version 2 compact blocks are post-segwit (wtxids)

The cmpctblock message is a reply to a getdata message which requested a block using the inventory type MSG_CMPCT_BLOCK. If the requested block was recently announced and is close to the tip of the best chain of the receiver and after having sent the requesting peer a sendcmpct message, nodes respond with a cmpctblock message containing data for the block.

If the requested block is too old, the node responds with a full non-compact block

Upon receipt of a cmpctblock message, after sending a sendcmpct message, nodes should calculate the short transaction ID for each unconfirmed transaction they have available (ie in their mempool) and compare each to each short transaction ID in the cmpctblock message. After finding already-available transactions, nodes which do not have all transactions available to reconstruct the full block should request the missing transactions using a getblocktxn message.

A node must not send a cmpctblock message unless they are able to respond to a getblocktxn message which requests every transaction in the block. A node must not send a cmpctblock message without having validated that the header properly commits to each transaction in the block, and properly builds on top of the existing, fully-validated chain with a valid proof-of-work either as a part of the current most-work valid chain, or building directly on top of it. A node may send a cmpctblock message before validating that each transaction in the block validly spends existing UTXO set entries.

The cmpctblock message contains a vector of PrefilledTransaction whose structure is defined below.

GetBlockTxn

The getblocktxn message is defined as a message containing a serialized BlockTransactionsRequest message. Upon receipt of a properly-formatted getblocktxn message, nodes which recently provided the sender of such a message a cmpctblock message for the block hash identified in this message must respond with either an appropriate blocktxn message, or a full block message.

A blocktxn message response must contain exactly and only each transaction which is present in the appropriate block at the index specified in the getblocktxn message indexes list, in the order requested.

The structure of BlockTransactionsRequest is defined below.

BlockTxn

The blocktxn message is defined as a message containing a serialized BlockTransactions message. Upon receipt of a properly-formatted requested blocktxn message, nodes should attempt to reconstruct the full block by taking the prefilledtxn transactions from the original cmpctblock message and placing them in the marked positions, then for each short transaction ID from the original cmpctblock message, in order, find the corresponding transaction either from the blocktxn message or from other sources and place it in the first available position in the block then once the block has been reconstructed, it shall be processed as normal, keeping in mind that short transaction IDs are expected to occasionally collide, and that nodes must not be penalized for such collisions, wherever they appear.

The structure of BlockTransactions is defined below.

NotFound

The notfound message is a reply to a getdata message which requested an object the receiving node does not have available for relay. (Nodes are not expected to relay historic transactions which are no longer in the memory pool or relay set. Nodes may also have pruned spent transactions from older blocks, making them unable to send those blocks.)

The format and maximum size limitations of the notfound message are identical to the inv message; only the message header differs.

Tx

The tx message transmits a single transaction in the raw transaction format. It can be sent in a variety of situations;

• Transaction Response: CICOIN Core and CICOIN will send it in response to a getdata message that requests the transaction with an inventory type of MSG_TX.
• MerkleBlock Response: CICOIN Core will send it in response to a getdata message that requests a merkle block with an inventory type of MSG_MERKLEBLOCK. (This is in addition to sending a merkleblock message.) Each tx message in this case provides a matched transaction from that block.
• Unsolicited: CICOIN will send a tx message unsolicited for transactions it originates.

For an example hexdump of the raw transaction format, see the raw transaction section.

Control Messages

The following network messages all help control the connection between two peers or allow them to advise each other about the rest of the network.

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.

Each encapsulated network IP address currently uses the following structure:

The following annotated hexdump shows part of an addr message. (The message header 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)

Alert

The legacy p2p network alert messaging system has been retired; however, internal alerts, partition detection warnings and the -alertnotify option features remain. See Alert System Retirement for details.

FeeFilter

The feefilter message is a request to the receiving peer to not relay any transaction inv messages to the sending peer where the fee rate for the transaction is below the fee rate specified in the feefilter message.

The feefilter messages allows a node to inform its peers that it will not accept transactions below a specified fee rate into its mempool, and therefore that the peers can skip relaying inv messages for transactions below that fee rate to that node.

The receiving peer may choose to ignore the message and not filter transaction inv messages.

The fee filter is additive with bloom filters. If an SPV client loads a bloom filter and sends a feefilter message, transactions should only be relayed if they pass both filters.

Note however that feefilter has no effect on block propagation or responses to getdata messages. For example, if a node requests a merkleblock from its peer by sending a getdata message with inv type MSG_FILTERED_BLOCK and it has previously sent a feefilter to that peer, the peer should respond with a merkleblock containing all the transactions matching the bloom filter, even if they are below the feefilter fee rate.

inv messages generated from a mempool message are subject to a fee filter if it exists.

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

FilterAdd

The filteradd message tells the receiving peer to add a single element to a previously-set bloom filter, such as a new public key. 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.

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 TXID. (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

The filterclear message tells the receiving peer to remove a previously-set bloom filter. 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.

CICOIN 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

The filterload message tells the receiving peer to filter all relayed transactions and requested merkle blocks through the provided filter. This allows clients to receive transactions relevant to their wallet plus a configurable rate of false positive transactions which can provide plausible-deniability privacy.

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

GetAddr

The getaddr message requests an addr message from the receiving node, 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.

Ping

The ping message helps confirm that the receiving peer 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.

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

0094102111e2af4d ... Nonce

Pong

The pong message replies to a ping message, proving to the pinging node that the ponging node is still alive. CICOIN 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

The reject message informs the receiving node that one of its previous messages has been rejected.

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.

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

SendHeaders

The sendheaders message tells the receiving peer to send new block 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.

VerAck

The verack message acknowledges a previously-received version message, informing the connecting node 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 node to the receiving node at the beginning of a connection. Until both peers 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.

The following service identifiers have been assigned.

Note: Protocol version 70001 introduced the optional relay field, adding the possibility of an additional byte to the version message. This introduces an incompatibility with implementations of lower protocol versions which validate the version message size. When implementing support for protocol versions less than 70001 you may want to handle the case of a peer potentially sending an extra byte, treating it as invalid only in the case of a requested protocol version less than 70001.

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.)

72110100 ........................... Protocol version: 70002
0100000000000000 ................... Services: NODE_NETWORK
bc8f5e5400000000 ................... Epoch time: 1415483324

0100000000000000 ................... Receiving node's services
00000000000000000000ffffc61b6409 ... Receiving node's IPv6 address
208d ............................... Receiving node's port number

0100000000000000 ................... Transmitting node's services
00000000000000000000ffffcb0071c0 ... Transmitting node's IPv6 address
208d ............................... Transmitting node's port number

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

0f ................................. Bytes in user agent string: 15
2f5361746f7368693a302e392e332f ..... 

cf050500 ........................... Start height: 329167
01 ................................. Relay flag: true

CICOIN CORE APIs

Remote Procedure Calls (RPCs)

CICOIN Core provides a remote procedure call (RPC) interface for various administrative tasks, wallet operations, and queries about network and block chain data.

If you start CICOIN Core using cicoin-qt, the RPC interface is disabled by default. To enable it, set server=1 in cicoin.conf or supply the -server argument when invoking the program. If you start CICOIN Core using cicoin, the RPC interface is enabled by default.

The interface requires the user to provide a password for authenticating RPC requests. This password can be set either using the rpcpassword property in cicoin.conf or by supplying the -rpcpassword program argument. Optionally a username can be set using the rpcuser configuration value. See the Examples Page for more information about setting CICOIN Core configuration values.

Open-source client libraries for the RPC interface are readily available in most modern programming languages, so you probably don’t need to write your own from scratch. CICOIN Core also ships with its own compiled C++ RPC client, cicoin-cli, located in the bin directory alongside cicoin and cicoin-qt. The cicoin-cli program can be used as a command-line interface (CLI) to CICOIN Core or for making RPC calls from applications written in languages lacking a suitable native client. The remainder of this section describes the CICOIN Core RPC protocol in detail.

The CICOIN Core RPC service listens for HTTP POST requests on port 8332 in mainnet mode or 18332 in testnet or regtest mode. The port number can be changed by setting rpcport in cicoin.conf. By default the RPC service binds to your server’s localhost loopback network interface so it’s not accessible from other servers. Authentication is implemented using HTTP basic authentication. RPC HTTP requests must include a Content-Type header set to text/plain and a Content-Length header set to the size of the request body.

The format of the request body and response data is based on version 1.0 of the JSON-RPC specification. Specifically, the HTTP POST data of a request must be a JSON object with the following format:

In the table above and in other tables describing RPC input and output, we use the following conventions

• “→” indicates an argument that is the child of a JSON array or JSON object. For example, “→ → Parameter” above means Parameter is the child of the params array which itself is a child of the Request object.
• Plain-text names like “Request” are unnamed in the actual JSON object
• Code-style names like params are literal strings that appear in the JSON object.
• “Type” is the JSON data type and the specific CICOIN Core type.
• “Presence” indicates whether or not a field must be present within its containing array or object. Note that an optional object may still have required children.

The HTTP response data for a RPC request is a JSON object with the following format:

As an example, here is the JSON-RPC request object for the hash of the genesis block:

{
    "method": "getblockhash",
    "params": [0],
    "id": "foo"
}

The command to send this request using cicoin-cli is:

cicoin-cli getblockhash 0

Alternatively, we could POST this request using the cURL command-line program as follows:

curl --user ':my_secret_password' --data-binary '''
  {
      "method": "getblockhash",
      "params": [0],
      "id": "foo"
  }''' \
  --header 'Content-Type: text/plain;' localhost:8332

The HTTP response data for this request would be:

{
    "result": "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f",
    "error": null,
    "id": "foo"
}

Note: In order to minimize its size, the raw JSON response from CICOIN Core doesn’t include any extraneous whitespace characters. Here we’ve added whitespace to make the object more readable. Speaking of which, cicoin-cli also transforms the raw response to make it more human-readable. It:

• Adds whitespace indentation to JSON objects
• Expands escaped newline characters (\n) into actual newlines
• Returns only the value of the result field if there’s no error
• Strips the outer double-quotes around results of type string
• Returns only the error field if there’s an error

Continuing with the example above, the output from the cicoin-cli command would be simply:

000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f

If there’s an error processing a request, CICOIN Core sets the result field to null and provides information about the error in the error field. For example, a request for the block hash at block height -1 would be met with the following response (again, whitespace added for clarity):

{
    "result": null,
    "error": {
        "code": -8,
        "message": "Block height out of range"
    },
    "id": "foo"
}

If cicoin-cli encounters an error, it exits with a non-zero status code and outputs the error field as text to the process’s standard error stream:

error: {"code": -8, "message": "Block height out of range"}

Starting in CICOIN Core version 0.7.0, the RPC interface supports request batching as described in version 2.0 of the JSON-RPC specification. To initiate multiple RPC requests within a single HTTP request, a client can POST a JSON array filled with Request objects. The HTTP response data is then a JSON array filled with the corresponding Response objects. Depending on your usage pattern, request batching may provide significant performance gains. The cicoin-cli RPC client does not support batch requests.

To keep this documentation compact and readable, the examples for each of the available RPC calls will be given as cicoin-cli commands:

cicoin-cli [options]    ...

This translates into an JSON-RPC Request object of the form:

{
    "method": "<method name>",
    "params": [ "<param1>", "<param2>", "..." ],
    "id": "foo"
}

[]proper money handling if you write programs using the JSON-RPC interface, you must ensure they handle high-precision real numbers correctly. See the Proper Money Handling CICOIN Wiki article for details and example code.

Blockchain RPCs

• GetBestBlockHash: returns the hash of the best (tip) block in the longest blockchain.
• GetBlock: gets a block with a particular header hash from the local block database either as a JSON object or as a serialized block.
• GetBlockChainInfo: returns an object containing various state info regarding blockchain processing.
• GetBlockCount: returns the number of blocks in the longest blockchain.
• GetBlockHash: returns hash of block in best-block-chain at height provided.
• GetBlockHeader: if verbose is false, returns a string that is serialized, hex-encoded data for blockheader ‘hash’.
• GetBlockStats: compute per block statistics for a given window.
• GetChainTips: return information about all known tips in the block tree, including the main chain as well as orphaned branches.
• GetChainTxStats: compute statistics about the total number and rate of transactions in the chain.
• GetDifficulty: returns the proof-of-work difficulty as a multiple of the minimum difficulty.
• GetMemPoolAncestors: if txid is in the mempool, returns all in-mempool ancestors.
• GetMemPoolDescendants: if txid is in the mempool, returns all in-mempool descendants.
• GetMemPoolEntry: returns mempool data for given transaction.
• GetMemPoolInfo: returns details on the active state of the TX memory pool.
• GetRawMemPool: returns all transaction ids in memory pool as a json array of string transaction ids.
• GetTxOut: returns details about an unspent transaction output.
• GetTxOutProof: returns a hex-encoded proof that
• GetTxOutSetInfo: returns statistics about the unspent transaction output set.
• PreciousBlock: treats a block as if it were received before others with the same work.
• PruneBlockChain: does PruneBlockChain.
• SaveMemPool: dumps the mempool to disk.
• ScanTxOutSet: eXPERIMENTAL warning: this call may be removed or changed in future releases.
• VerifyChain: verifies blockchain database.
• VerifyTxOutProof: verifies that a proof points to a transaction in a block, returning the transaction it commits to and throwing an RPC error if the block is not in our best chain.

Control RPCs

• GetMemoryInfo: returns an object containing information about memory usage.
• GetRpcInfo: returns details of the RPC server.
• Help: list all commands, or get help for a specified command.
• Logging: gets and sets the logging configuration.
• Stop: stop CICOIN server.
• Uptime: returns the total uptime of the server.

Generating RPCs

• Generate: mine up to nblocks blocks immediately (before the RPC call returns) to an address in the wallet.
• GenerateToAddress: mine blocks immediately to a specified address (before the RPC call returns).

Mining RPCs

• GetBlockTemplate: if the request parameters include a ‘mode’ key, that is used to explicitly select between the default ‘template’ request or a ‘proposal’.
• GetMiningInfo: returns a json object containing mining-related information.
• GetNetworkHashPs: returns the estimated network hashes per second based on the last n blocks.
• PrioritiseTransaction: accepts the transaction into mined blocks at a higher (or lower) priority.
• SubmitBlock: attempts to submit new block to network.
• SubmitHeader: decode the given hexdata as a header and submit it as a candidate chain tip if valid.

Network RPCs

• AddNode: attempts to add or remove a node from the addnode list.
• ClearBanned: clear all banned IPs.
• DisconnectNode: immediately disconnects from the specified peer node.
• GetAddedNodeInfo: returns information about the given added node, or all added nodes (note that onetry addnodes are not listed here).
• GetConnectionCount: returns the number of connections to other nodes.
• GetNetTotals: returns information about network traffic, including bytes in, bytes out, and current time.
• GetNetworkInfo: returns an object containing various state info regarding P2P networking.
• GetNodeAddresses: return known addresses which can potentially be used to find new nodes in the network.
• GetPeerInfo: returns data about each connected network node as a json array of objects.
• ListBanned: list all banned IPs/Subnets.
• Ping: requests that a ping be sent to all other nodes, to measure ping time.
• SetBan: attempts to add or remove an IP/Subnet from the banned list.
• SetNetworkActive: disable/enable all p2p network activity.

Rawtransactions RPCs

• AnalyzePsbt: analyzes and provides information about the current status of a PSBT and its inputs.
• CombinePsbt: combine multiple partially signed Bitcoin transactions into one transaction.
• CombineRawTransaction: combine multiple partially signed transactions into one transaction.
• ConvertToPsbt: converts a network serialized transaction to a PSBT.
• CreatePsbt: creates a transaction in the Partially Signed Transaction format.
• CreateRawTransaction: create a transaction spending the given inputs and creating new outputs.
• DecodePsbt: return a JSON object representing the serialized, base64-encoded partially signed Bitcoin transaction.
• DecodeRawTransaction: return a JSON object representing the serialized, hex-encoded transaction.
• DecodeScript: decode a hex-encoded script.
• FinalizePsbt: finalize the inputs of a PSBT.
• FundRawTransaction: add inputs to a transaction until it has enough in value to meet its out value.
• GetRawTransaction: return the raw transaction data.
• JoinPsbts: joins multiple distinct PSBTs with different inputs and outputs into one PSBT with inputs and outputs from all of the PSBTs No input in any of the PSBTs can be in more than one of the PSBTs.
• SendRawTransaction: submits raw transaction (serialized, hex-encoded) to local node and network.
• SignRawTransactionWithKey: sign inputs for raw transaction (serialized, hex-encoded).
• TestmemPoolAccept: returns result of mempool acceptance tests indicating if raw transaction (serialized, hex-encoded) would be accepted by mempool.
• UtxoUpdatePsbt: updates a PSBT with witness UTXOs retrieved from the UTXO set or the mempool.

Wallet RPCs

• AbandonTransaction: marks an in-wallet transaction and all its in-wallet descendants as abandoned. This allows their inputs to be respent.
• AbortRescan: Stops current wallet rescan
• AddMultiSigAddress: adds a P2SH multisig address to the wallet.
• BackupWallet: safely copies current wallet file to destination, which can be a directory or a path with filename.
• BumpFee: bumps the fee of an opt-in-RBF transaction T, replacing it with a new transaction B.
• CreateWallet: creates and loads a new wallet.
• DumpPrivKey: reveals the private key corresponding to ‘address’.
• DumpWallet: dumps all wallet keys in a human-readable format to a server-side file.
• EncryptWallet: encrypts the wallet with ‘passphrase’.
• GetAddressesByLabel: returns the list of addresses assigned the specified label.
• GetAddressInfo: return information about the given bitcoin address.
• GetBalance: returns the total available balance.
• GetNewAddress: returns a new Bitcoin address for receiving payments.
• GetRawChangeAddress: returns a new Bitcoin address, for receiving change.
• GetReceivedByAddress: returns the total amount received by the given address in transactions with at least minconf confirmations.
• GetReceivedByLabel: returns the total amount received by addresses with in transactions with at least [minconf] confirmations.
• GetTransaction: get detailed information about in-wallet transaction .
• GetUnconfirmedBalance: returns the server’s total unconfirmed balance.
• GetWalletInfo: returns an object containing various wallet state info.
• ImportAddress: adds an address or script (in hex) that can be watched as if it were in your wallet but cannot be used to spend.
• ImportMulti: import addresses/scripts (with private or public keys, redeem script (P2SH)), optionally rescanning the blockchain from the earliest creation time of the imported scripts.
• ImportPrivKey: adds a private key (as returned by dumpprivkey) to your wallet.
• ImportPrunedFunds: imports funds without rescan.
• ImportPubKey: adds a public key (in hex) that can be watched as if it were in your wallet but cannot be used to spend.
• ImportWallet: imports keys from a wallet dump file (see dumpwallet).
• KeyPoolRefill: fills the keypool.
• ListAddressGroupings: lists groups of addresses which have had their common ownership made public by common use as inputs or as the resulting change in past transactions.
• ListLabels: returns the list of all labels, or labels that are assigned to addresses with a specific purpose.
• ListLockUnspent: returns list of temporarily unspendable outputs.
• ListReceivedByAddress: list balances by receiving address.
• ListReceivedByLabel: list received transactions by label.
• ListSinceBlock: get all transactions in blocks since block [blockhash], or all transactions if omitted.
• ListTransactions: if a label name is provided, this will return only incoming transactions paying to addresses with the specified label.
• ListUnspent: returns array of unspent transaction outputs with between minconf and maxconf (inclusive) confirmations.
• ListWalletDir: returns a list of wallets in the wallet directory.
• ListWallets: returns a list of currently loaded wallets.
• LoadWallet: loads a wallet from a wallet file or directory.
• LockUnspent: updates list of temporarily unspendable outputs.
• RemovePrunedFunds: deletes the specified transaction from the wallet.
• RescanBlockChain: rescan the local blockchain for wallet related transactions.
• SendMany: send multiple times.
• SendToAddress: send an amount to a given address.
• SetHdSeed: set or generate a new HD wallet seed.
• SetLabel: sets the label associated with the given address.
• SetTxFee: set the transaction fee per kB for this wallet.
• SignMessage: sign a message with the private key of an address.
• SignRawTransactionWithWallet: sign inputs for raw transaction (serialized, hex-encoded).
• UnloadWallet: unloads the wallet referenced by the request endpoint otherwise unloads the wallet specified in the argument.
• WalletCreatefundedPsbt: creates and funds a transaction in the Partially Signed Transaction format.
• WalletLock: removes the wallet encryption key from memory, locking the wallet.
• WalletPassphrase: stores the wallet decryption key in memory for ‘timeout’ seconds.
• WalletPassphraseChange: changes the wallet passphrase from ‘oldpassphrase’ to ‘newpassphrase’.
• WalletProcessPsbt: update a PSBT with input information from our wallet and then sign inputs that we can sign for.