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TRON Core Devs Meeting 03 Notes

Meeting Date/Time: Mon, Mar 02, 2020 07:00 UTC

Meeting Duration: 1 hour

GitHub Agenda Page

Audio/Video of the meeting

Agenda

java-tron latest updates

TRON multi-signature implementation

  • Multi-signature introduction.
  • TRON account multi-signature. TIP 16
  • TRON multi-signature permission operation. TIP 105
  • Comparision with other cryptographic multi-signature scheme.
  • Comparision with other implementation of multi-signature in blockchain industry.
  • The optimization of multi-signature on the blockchain.

java-tron latest updates

  • Taihao

    • So, this week TRON Network just approved the proposal 32 for solidity 0.5.9 functionality upgrade.
    • This proposal contains several new TVM Instructions and new functionality.
    • Some details are here:
    • In TIP 43, we provide a new precompile function to help contract to verify a group of signature with lower energy and lower cpu time, which is an optimization for ecrecover function.
    • In TIP 44, we provide a more safer way isContract() to judge whether an address is contract or not.
    • And DApp developer can simply check isContract property for an address object for this purpose.
    • In TIP 54, now address.transfer() function support transfer TRX to an non-existing address and create an new account for the address.
    • I think this will do a lot of convenience for DApp developers for the non-existing address transferring case.
    • For TIP 60, we provide a new precompile function to help contract to verify multi-signature messages.
    • This is the special implementation for just TRON accounts.

  • Bruce

    • To keep up with the latest upgrade, what do the dapp developers need to do?

  • Taihao

    • So, if you are a fullnode maintainer, you may have to upgrade your fullnode version to Odyssey 3.6.6
    • And this tip is more related to DApp developers.
    • If I were a dapp developer I maybe excited about tip 54,
    • since it can save my energy and lower my cost when handling exception for transfer function.
    • And also if I have logic about signature validation expecially to validate more than 1 signature in a single smart contract transaction,
    • I would like to check TIP 43.

Multi-signature introduction

  • Sakary

    • First, let me introduce some basic situations of multi-signature protocols.
    • Normal cryptocurrency transaction requires one signature.
    • Well, multi-signature means more than one.
    • It gives every signature a weight, the total weight must reach the customized threshold before executed.
    • Using multi-signature, an account can be managed by several private keys,
    • and the transactions created in a specific account can be signed by serval people.
    • I'm going to talk about the specification of multi-signature operation permission and the way to implement user-defined operation permission for multi-signature.

TRON account multi-signature

  • Sakary

    • Let’s see the protocol design.
    • The relating structures in protocol including Account, Permission, Key, Transaction.
    • Account: There are 3 different roles of permission: owner, witness and active.
    • Owner has the right to execute all the contracts, witness is for super representatives, active contains a set of contracts selected execution permissions
    • Permission: Each bit of structure member operations, 1 means true, 0 means not, index refers to the definition of Transaction.
    • like, the index of AccountPermissionUpdateContract in ContractType is 46.
    • Key: Includes 2 members: address - The account address，weight - The signature weight
    • Transaction: There is a field called Permission_id here, and it corresponds to id in Permission.

  • Michael

    • If increase the system contract in the future, will this length be insufficient?

  • Sakary

    • The operations support up to 256 different type of contract.
    • For now, the maximum index of the system contract is no more than 50.
    • As the number of system contract will not increase very quickly, it is enough within a period of time.
    • OK? Then I'm going to talk about different types of permission.
    • Owner permission is used to control account ownership and adjust permission structure.
    • It can execute all the contracts, so it is the top one.
    • Owner permission has some other features: There is a default owner if owner permission is null.
    • At the time you create a new account, the address will be added automatically .

  • Bill

    • What is the relationship between this owner-permission and the owner address field in the account protocol?

  • Sakary

    • The account field represents the address of this account, which is not allowed to be modified.
    • But you can do it on own-permission.

  • Bill

    • I have the account's private key, but my own-permission has been given to others.
    • Can I still control this account?

  • Sakary

    • No, even if you have a private key, you cannot sign it.
    • All good? Then let's move on to witness permission.
    • Witness is also called Super representatives, we call them SR usually.
    • They can use this kind of permission to manage block producing.
    • Only witness accounts are able to have this permission.
    • In a simple scenario:
    • A SR deploys a witness node on cloud server.
    • In order to keep the account safe, only producing permission will be given.
    • That account cannot do anything other than producing block, like transfer,
    • so even if the account information is known to others, their possessions will not be lost.

  • Sean

    • If I don't configure the witness permission, do I need to modify my configuration file?

  • Sakary

    • If you're not running a witness node, that means you don't have witness permission, so there is no need to do this.
    • Ok? Next is Active Permission:
    • Active permission is composed of a set of contract execution permission,
    • like creating a new account, transferring , etc.
    • The most important feature of active permission is that you can customize permissions.
    • For example, you can allow others to freeze or unfreeze your trx, and give the transfer right to several people.
    • One thing need to be noticed is that if you have the active permission to execute permission of AccountPermissionUpdateContract,
    • you have the highest permission.
    • This requires special attention.

  • Bill

    • So, just like upgrade permission into owner permission, which is the highest one....
    • But, is there any secure problem?

  • Sakary

    • We offer a high degree of flexibility.
    • But as long as you pay attention when setting permissions,
    • set active permission of AccountPermissionUpdateContract to false, there will be no problems.

  • Matthew

    • If I use AccountPermissionUpdateContract to active permission, can I revert the permission?

  • Sakary

    • Yes, you can use AccountPermissionUpdateContract to revert it again.

  • Matthew

    • How many multi-signature transactions there are in tron network now?

  • Sakary

    • I have not statistic the data. After these meeting, I will publish the specified data.

TRON multi-signature permission operation

  • Benson

    • Now, I would like to talk about Multi-signature permission operation.
    • It is proposed on TIP 105. Currently still in the draft phase.
    • Can you see my screen now?

  • Taihao

    • What is the relationship between TIP 16 just mentioned and the TIP 105?

  • Benson

    • TIP105 is a supplement of TIP16, it described how Multi-signature permission is managed.
    • Sakary introduced the three types of permission in Multi-signature,
    • to implement this, three attributes were added to Account,
    • they are owner_permission, witness_permission and active_permission.
    • At the same time, we add 3 attributes in Permission definition.
    • They are threshold, keys, and operations.

  • Federico

    • what do these three members mean?

  • Benson

    • The ‘threshold’ indicates the threshold of signature weight.
    • The ‘keys’ include two data items: address and weight.
    • The member "operation" has 32 bytes which means 256 b and each bit represents one ContractType,
    • the value of that bit represents the permission of that ContractType.

  • Bill

    • the total bits are 256, which means at most 256 contractType, Is this enough in future?

  • Benson

    • We have now defined 32 contractType, which is far away from 256,
    • as Sakary mentioned, The number of system contract will not increase very quickly, basically,
    • we would say there will be no risk in short-term,
    • and we will also look for long-term solution if it is close to 256.

  • Federico

    • What are the contractTypes defined at present and how to define it in operations?

  • Benson

    • Ok, here you can see the ContractType definition list,
    • Currently, we have AccountCreateContract, TransferContract, TransferAssetContract, etc.
    • The operations value is used to defined the permissions,
    • i will introduce how it works, each bit of the operation represents one contractType.
    • the first bit represents AccountCreateContract and second bits means TransferContract.
    • for example, if the value of first bit equals 1,
    • it means the it has the AccountCreateContract permission,
    • if the value of the second bit equals 0 means TransferContract is not allowed.
    • by this rule, operation value will be generated based on selected permissions.
    • And you can find more technical details here if you are interested.
    • one note for all of you, please pay attention to AccountPermissionUpdateContract permission,
    • once user get this permission, they can modify the permissions.

  • Taihao

    • What's the advantage of TIP105?

  • Benson

    • With this Multi-signature permission operation, The account permission control is more flexible,
    • and it can meet different requirements of permission management.

  • Taihao

    • If the users got the AccountPermissionUpdateContract permission, how can they change the permission?

  • Benson

    • first, they need to call getaccount function to query the account and get the original permission
    • second, they will change permission
    • third, a new transaction is built and signed to satisfy the multi-signature requirement.
    • at last, they will send transaction to blokchain and get the new permissions.

Comparision with other cryptographic Multi-signature scheme

  • Wayne

    • Now, Let's talk about the comparisons of Multi-signature implementations from cryptographic view.

  • Sean

    • What is the explict cryptographic algorithm of TRON Multi-signature implementation ?

  • Wayne

    • TRON Multi-signature is based on ECDSA signature.
    • the full name of ECDSA is Elliptic Curve Digital Signature Algorithm.
    • It’s a variant of the Digital Signature Algorithm (DSA) which uses elliptic curve cryptography.

  • Brown

    • what's about its security?

  • Wayne

    • Its security is based on the elliptic curve discrete logarithm.
    • The signature of ECDSA is consist of two scalars, usually called r and s.
    • It's simple and easy to implement.

  • Sean

    • Are there any other cryptographic technology which can implement the Multi-signature?

  • Wayne

    • As I know, there are two other cryptographic algorithms that can be used for Multi-signature.
    • They are Schnorr signature and BLS signature.
    • All of them are elliptic curve signature.

  • Benson

    • what's difference for the ECDSA, schnorr and BLS?

  • Wayne

    • Schnorr signature is similar with ECDSA in algorithm structure,
    • but its signature is consist of one elliptic curve point and one scalar.

  • Benson

    • what's the advantages and disadvantages of Schnorr signature?

  • Wayne

    • Schnorr can implement the batch signature verification, key aggregation and the Multi-signature.
    • but it requests multiple rounds of interaction between the signers during Multi-signature implementation
    • Furthermore, The m-n Multi-signature needs to construct the merkle tree and leads to space cost.
    • I would say Schnorr Multi-signature is not efficient in practical use.

  • Brown

    • what about BLS signature?

  • Wayne

    • BLS signature is based on elliptic curve and bilinear parings.
    • It can implement the signature aggregation, key aggregation, and Multi-signature.
    • BLS algorithm is quite simple, the signature result is only one elliptic curve point.

  • Benson

    • Can ECDSA be replaced by BLS in TRON Multi-signature?

  • Wayne

    • BLS do have many advantages, however, it is not perfect,
    • it requests parameters initialization.
    • and The bilinear paring in BLS is very complex,
    • It is not efficient in practice.
    • Further optimization is needed if we want to use it.

  • Benson

    • I have heard about the BLS is utilized in Ethereum for Multi-signature implement, why they choose BLS?

  • Wayne

    • Actually, BLS algorithm is simple and easy to implement.
    • The low efficiency is relative to ECDSA.
    • If you don't care much about efficiency, it should be ok to use it.
    • In a word, the ECDSA is simple and efficient compared to Schnorr and BLS signature.
    • that is why it is used in TRON.

Comparison with other implementation of Multi-Signature in block industry

  • Wayne

    • In the past, I did some research on some other implementations in blockchain industry.
    • Essentially speaking, the multisignature functions in BTC, ETH, EOS and Tron are the same,
    • they both want to resolve the problem of controlling assets by multiple people, and to enhance its security.
    • But for the implementation, they also have some differences.
    • For BTC, it is called M-of-N Multisig,
    • which means a pubkey script that provides M number of pubkeys
    • and requires the corresponding signature script provide m minimum number signatures corresponding to the provided pubkeys,
    • and M is no bigger than N.

  • Bill

    • Is there any difference in the use of BTC's multi-signature?

  • Wayne

    • Before we use multisignature in BTC, we should create M-of-N redeemScript by using N public keys,
    • and use this script to do multisignature.
    • For ETH, is use smart contract to implement multisignature and users should write smart contract by themselves.
    • Because ETH is turing-complete, the code can be anything, including a multisignature-type wallet.
    • It is more flexible, but it also brings some more work for the uses and it has potential safety risks.

  • Michael

    • In other words, isn't the multi-signature of ETH provided by the system?

  • Wayne

    • As far as I know, ETH only provides basic signature verification operations for contract calls.
    • For EOS, the multi-signature mechanism is similar with Tron in some aspects,
    • it also has permission, weight, and threshold.
    • But in the permission, every account has two default named permissions when created, owner and active.
    • They have a parent-child relationship by default,
    • although this can be customized by adding other permission levels and hierarchies.
    • As a result, the active permission can do anything the owner permission can,
    • except changing the keys associated with the owner.
    • More than that, it allows to create custom hierarchical permissions that stem from the owner permission.
    • Each account's permission can be linked to an authority table
    • which is used to determine whether a given action authorization can be satisfied,
    • it is similar to the operations bytes in Tron.
    • In conclusion, we just talk about the implementation in other block industries briefly, not including the details.

  • Bruce

    • What feature of TRON multi-signature is unique compared to others and what's the innovation?

  • Wayne

    • This is a good question. Actually, Multi-signature is relatively mature,
    • each blockchain implements it depends on its own basic technologies, such as the account model and transaction.
    • In general, Tron multi-signature is very flexible and it can handled very easily.
    • You can study how to use it in a very short time.
    • It uses operation in permission to determine which type of transmission can be signed by which permission,
    • and users can change it by themselves. Users have the full control.
    • More than that, we provide the witness permission for SR to solve their special problems.
    • We specify witness permission for SR, Authorized use can only generate blocks but nothing,
    • it's very useful in maintenance node.

  • Bruce

    • Thank you,
    • we need to discuss the optimization of multi-signature on the blockchain.

The optimization of multi-signature on the blockchain

  • Sean

    • yes
    • Performance is a particular concern in the selection of our solution.
    • Since we do not use the aggregate signatures, if multiple people sign a transaction,
    • we will face the problem of verifying multiple signatures in one transaction.
    • So we need to discuss how to improve the performance.
    • Currently, TRON have limited the number of signatures for a transaction.

  • Bruce

    • Just by limiting the number of signatures does not seem to be a perfect solution
    • and may cause restrictions on using.

  • Sean

    • Yes, the current limit is not too small, and it will be able to meet the most use cases.
    • We also adopted a method of verifying signatures in parallel.

  • Bruce

    • Can you explain in specific how this is implemented?

  • Sean

    • This problem involves a specific code.
    • Let me briefly describe，We divide all transactions in a block into two parts for execution,
    • first perform signature verification together,
    • and then perform specific tasks, such as transferring, freezing, etc.
    • The former part is parallel and the latter part is serial.

  • Bruce

    • Why the verification and execution can not run in parallel?

  • Sean

    • Because verifying the signature does not change the data in the database,
    • which is stateless, but the execution process changes the state.

  • Benson

    • Can you talk more about how to implement parallelism in the code?

  • Sean

    • This may be a bit detailed, but it doesn't matter,
    • it is actually a thread pool,
    • and the signature of each transaction is given to a thread to verify.

  • Benson

    • A transaction is given to a thread.
    • If a transaction contains multiple signatures,
    • then this transaction still takes more time to execute than other transactions.
    • It seems that it does not solve the problem?
    • Is it better that one signature is executed by one thread?

  • Sean

    • The scheme you said is feasible, but the effect is the same.
    • For example, there are more than 100 transactions in a block, most of which are ordinary transactions.
    • A node assumes have16 cores, then a thread needs to perform about 10 tasks,
    • and one or two threads may only process two multi-signature transactions.
    • There will not be an increase in overall time.

  • Federico

    • I think aggregate signature is a good way to break the number limit of multi-signatures with higher efficiency,
    • maybe you can use it to optimize the performance？

  • Sean

    • Yeah, it sounds like a good idea.
    • Aggregate signature is efficient for batch signature verification.
    • we may need further research to see whether they are fit for Multi-signature.

  • Benson

    • I heard that ETH2.0 has adopted the BLS aggregation signature scheme.
    • Have you considered it?

  • Sean

    • BLS aggregation signatures are very attractive and we have been paying attention.
    • But this solution is not perfect, such as a longer verification time,
    • which is an order of magnitude slower than ECDSA.
    • We also believe that efficiency issues will eventually be resolved.

  • Bruce

    • To use multisignature in actual senarios,
    • like I sign a transaction and this transaction also need Benson's signatures to execute.
    • So I need to send the transaction to Benson or Sakary though Slack or other communication apps.
    • Is there a way Benson and Sakary can reveive a sign notice automatically in their wallet after I sign the transaction?

  • Sean

    • I think you can use tronscan.

Next call

  • Bruce

    • that's pretty much all we need to talk about today
    • for the next meeting, Cryptochain want to discuss bad node actors,
    • like how to penalize the ones dropping block or not updating in time?
    • I think that is a good topic.
    • if there's sth you want to talk about or to discuss,
    • you can write the topic on the agenda issue of meeting four after I create the issue.
    • todays meeting content will be noted and published on github.
    • OK, Any other questions before I move on?
    • OK, Our The meeting ends here.
    • Have a good day.
    • See you guys.

Attendees

  • Bruce
  • Taihao
  • Federico
  • Tim
  • Bill
  • Michael
  • Brown
  • Sean
  • Sakary
  • Matt
  • Bill
  • Matthew
  • Richard
  • Daniel