Implementing JPMC Quorum Using Azure Blockchain As A Service

One Size Does Not Fit All :   As  we position  blockchain  enabled  de-centralized  and  distributed  applications  for  enterprise,  there   could  be multiple  needs  for  different  enterprises.  That  is the reason  initially permissionless  public blockchain  started  the  transition  and subsequently  the  permissioned  private blockchain  continued  with the  transformation.

However  even  the  permissioned  private  blockchain  perceived  to  have  some  limitations  with respect to enterprise compliance  needs,  and  hence  there  is a  thought  process  to  customize  the  private  blockchain further  and  this  has  resulted  in  the  creation of  new  blockchain platform Quorum  by JP Morgan.

Quorum is an Ethereum-based distributed ledger protocol with transaction/contract privacy and new consensus mechanisms.

What  makes  Quorum  different  from  Standard Ethereum  is  the  concept  of  Private Transactions. Quorum supports Transaction-level privacy and network-wide transparency, customizable to business requirements.

Quorum Implementation Using Azure  Blockchain As A Service:    Azure BaaS  provides a  easy to use  template  a  reference  implementation  of Quorum  On  Azure.  The  template  only  looks for minimal  parameters  like.

• VM size
• Storage Account
• Public Key  for  authentication
• Network Related Information

Once  the  node  is created,  we  can SSH into the  node  and  start  the node operations.

Two  Script  file s  (init.sh,  start.sh)  which  needs  to be run  in  sudo  mode  are  required to start the  Quorum Blockchain.

This  setup  simulates  7  Quorum  Nodes  in  a  single  host  and  a  list  of  configuration  files  tm1.conf...  tm7.conf  are  used  as  configuration  for the nodes.

For  example  the  following  command  is  used  to  Start the  logical  node  1.

PRIVATE_CONFIG=tm1.conf nohup geth --datadir qdata/dd1 $GLOBAL_ARGS --rpcport 22000 --port 21000 --unlock 0 --password passwords.txt 2

Similarly  all  the  7   nodes  at the end of  start.sh execution.

The  examples  work  well  with  the   IPC  interface  of  quorum. For  example the below  command executes  a  script  against  node 1.

 sudo PRIVATE_CONFIG=tm1.conf geth --exec 'loadScript("./chk.js")' attach ipc:qdata/dd1/geth.ipc

Private Transactions :   'Private Transactions' are those Transactions whose payload is only visible to the network participants whose public keys are specified in the privateFor parameter of the Transaction .   The following  is an example of  private  transaction.

var simple = simpleContract.new(42, {from:web3.eth.accounts[0], data: simpleCompiled[simpleRoot].code, gas: 300000, privateFor: ["ROAZBWtSacxXQrOe3FGAqJDyJjFePR5ce4TSIzmJ0Bc="]},

Here  the  PrivateFor   is  a  customized  version  of  transaction  specific  to Quorum. 

Is  Private  Transactions  will  be  a  acceptable  standard  in  Blockchain,  as  some  times  it  may  be viewed  as  bringing  centralized  control,  and  not  bringing  transparency  to  the  transactions. However  considering  the    Multi Bank Consortium,  all  banks  may wanted  to  share  the information  like KYC  to  prevent  issues  like  Money  laundering,  however  any  particular  two  banks  still  get into  private  transactions, which  other banks may  not be aware.