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# Transaction

# Transaction Identifier

Each transaction has an identifier (typically shortened as TX ID). It is defined as

blake3_hash(SCALE-encoded transaction binary data)

See serialization for more details about the transaction binary format.

# Witness

See signature-schemes for more details

# Textual Address Representation

Crypto.com Chain supports threshold / multi-signature addresses that are represented as a single hash (see signature-schemes) which is different from Ethereum.

To represent the underlying byte array in a textual form, Bech32 is used. The convention for the human-readable prefix is the following:

  • cro: mainnet payment
  • tcro: testnet payment
  • dcro: local devnet/regtest payment
  • staking addresses (see accounting) are textually represented in hexadecimal encoding to match the initial Ethereum ones

# Transaction Fees

The purpose of transaction fees in the initial prototype is an anti-spam measure, i.e. to prevent broadcasting valid transactions indefinitely. The general scheme is:

  • If the transaction type allows indefinite valid transactions in an immediate time span (e.g. "transfer"), a fee (calculated as below) must be paid -- i.e. each transaction should be validated that it included this sufficient fee. Note that the fee amount must be exactly equal to the computed one (this is to prevent errors where a much larger fee could be accidentally paid if the fee amount could be set arbitrarily large).
  • If the transaction type allows a limited number of valid transactions, there is no fee. One example is "unjail" where only one valid transaction can be sent for a given state after the unjailing period.

More details can be found in the transactions document.

(In the future, if necessary, a dynamic Dutch auction-style fee market may be introduced for congestion control -- this may, however, be outside of the consensus state machine, i.e. "off-chain", in order to incentivize full nodes or other network layers.)

# Fee Calculation

The initial prototype uses a linear fee system. The minimal transaction fee is defined according to the formula:

<BASE_AMOUNT> + <PER_BYTE> * size

BASE_AMOUNT and PER_BYTE are special network parameters in a fraction of CRO. size is the serialized transaction data’s size in bytes.

To verify a basic transaction one would need to check:

sum(inputs amounts) or account.unbonded/bonded == sum(outputs amounts) + fee

The transaction fee goes to the rewards pool to reward the validations.

# Transaction Types

# Basic Types (plain version):

:::tip NOTE All these types should also contain metadata, such as network ID. Furthermore, some of these transactions will be obfuscated to provide privacy protections to the users. :::

Tx type Inputs Outputs Fees involved? Obfuscated?
TransferTx UTXOs UTXOs Yes Yes
DepositStakeTx UTXOs Deposit the bonded amount to the specified account Yes Yes
WithdrawUnbondedTx Nonce, account UTXOs Yes Yes
UnbondStakeTx Nonce, amount, account Moves funds from bonded to unbonded under the same account with timelock Yes No

Please also refer to this flowchart that shows different types of transaction and how they interact with each other.

# Advanced Types:

Besides the above-mentioned basic transactions, there are some advanced types of transactions related to the council node and service node state metadata management, for example:

  • UnjailTx: This transaction can be broadcasted to un-jail a node. It takes nonce, account and has to be signed by the account’s corresponding key.
  • NodeJoinTx: Anyone who wishes to become a council node can broadcast this transaction. It takes council node data, staking address and has to be signed by the node's staking key. For further details on the process of joining the Crypto.com chain as a validator, please refer to this documentation.

:::tip Note There will be no transaction fee for advanced types Tx in the initial prototype. :::

# Cross-currency transactions and settlements

A proof of concept on the cross-currency transfers and settlement on CRO can be found in this repository. It demonstrates how to configure Interledger nodes for performing CRO-ETH cross-currency transactions between the Ethereum network (testnet or mainnet) and the CRO devnet.

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