NewChainBlind

NewChainBlind is an implementation of an anonymous transaction based on NewChain.

The project aims to hide the sender of the transaction, mainly through blind signature technology.

Application Case

Alice wants to transfer Bob to 1NEW, but she doesn't want others to know that she has transferred Bob.

Alice can hide her address by following the steps below:

graph TD
K[Bank]
A[Alice]
B[Bob]
A-->|1. Deposit|K
A-->|2. Blind|A
K-->|3. Sign|A
A-->|4. Pay|B
B-->|5. Verify|K
K-->|6. Send Token|B

Loading

1. Alice deposits 100NEW to Bank
   • Transfer to the address of Bank by NewPay or NewCommander
2. Alice performs blind signature
   • Alice builds a message with a denomination of 1NEW and adds a random string to the message body.

   m = (header info, denomination, serial number)
   

   • Alice blinds the message m through the PublicKey of the 1NEW denomination of Bank, and obtains the blinded message blinded and unblind factor unblinder.
3. Bank sign
   • Alice sends the denomination and the blinded message to the bank
   • Bank checks if Alice has enough denominations for her own
     • Returns an error if it does not;
     • If there is, subtract the NEW of the corresponding denomination;
   • Bank encrypts blinded with PrivateKey corresponding to its 1NEW denomination, and gets sig
   • Bank tells Alice about sig
4. Alice unblind
   • Alice get unblindSig by unblind factor unblinder and sig
5. Alice tells Bob the proof of 1NEW
   • Alice tells Bob the message body m and unblindSig
6. Bob verifies to the bank
   • Bob tells the bank the message body m and unblindSig from Alice, and tells the bank to transfer the 1NEW to him.
   • The bank verifies the message m and unblindSig with the 1NEW's PublicKey
7. After the verification is successful, Bank transfers Bob to 1NEW.

Related instructions

• The anonymity of the hidden transaction sent by the program will be affected by factors such as the number of deposits and withdrawals of the bank and the number of types of transaction denominations.
  1. Number of traders
     • The more bank deposits, the stronger the anonymity
  2. Denomination type
     • The less the bank's denomination, the stronger the anonymity

Reference material

1. Blind signature(Wikipedia)
2. Blind signatures(Birmingham)
3. e-cash(StackExchange)
4. Digital Cash(Birmingham)
5. Blind signatures for untraceable payments

QuickStart

Download from releases

Binary archives are published at https://release.cloud.diynova.com/newton/NewChainBlind/.

Building the source

install command

git clone https://github.com/newtonproject/newchain-blind.git && cd newchain-blind && make install

run newchain-blind

%GOPATH%/bin/newchain-blind

Usage

Help

Use command NewChainBlind help to display the usage.

Usage:
  NewChainBlind [flags]
  NewChainBlind [command]

Available Commands:
  account     Manage NewChain accounts
  balance     Get balance of address
  blind       Blind 1NEW for address
  deposit     Use the TxHash to deposit NEW(decimal not counted)
  faucet      Get free money for address
  help        Help about any command
  info        Show the info of the bank
  init        Initialize config file and bank
  sign        Sign blinded file for address of cash 1NEW
  unblind     Unblind 1NEW for address
  verify      Verify unblinder sign file and send 1NEW to address
  version     Get version of NewCommander CLI

Flags:
  -c, --config path            The path to config file (default "./config.toml")
  -h, --help                   help for NewChainBlind
  -i, --rpcURL url             NewChain json rpc or ipc url (default "https://rpc1.newchain.newtonproject.org")
  -w, --walletPath directory   Wallet storage directory (default "./wallet/")

Use "NewChainBlind [command] --help" for more information about a command.

Use config.toml

You can use a configuration file to simplify the command line parameters.

One available configuration file config.toml is as follows:

rpcurl = "https://rpc1.newchain.newtonproject.org"
usedhash = ["0xe5ed16d511bb6f511c04fdc19be38b47d3494844e94db04f36fe2c7d4348b75b"]
usedunblinderhash = ["0xb18f64a9cc9ce8082675b65c174041d5fe2fb7b4b2d50084961c280ebe896d29"]
walletpath = "./wallet/"

[balances]
  0x2a8996ebb0314717dfdcd879685a9246649d7bc1 = 1
  0x511eef866c847c78b3ff67b581064007166575b1 = 22
  0x97549e368acafdcae786bb93d98379f1d1561a29 = 53

[bank]
  address = "0x873054eAcB22516E1dBC966C9aE338eef40FE15c"
  cash = "1"
  rsapemprivatekeyfile = "./key.pem"
  rsapempublickeyfile = "./pubkey.pem"

• RPCUrl: the NewChain RPC URL
• WalletPath: the path of the keystore file
• Bank.Address: the address of the bank
• Bank.Cash: Bank-supported denomination type (unit: NEW), only 1NEW support
• Bank.RSAPEMPrivateKeyFile: path to the RSA PEM private key file
• Bank.RSAPEMPublicKeyFile: path to the RSA PEM Public key file

The following fields exist as database storage:

• UsedHash: the list of used hash when deposit to the bank
• UsedUnlinderHash: the sha256sum of used Unlinder when verify it
• Balances: the balance of users at the bank

Cmd

• account: Manage NewChain accounts, to create new account, list the accounts or update the password of the account
• balance: Get balance of address or all the address in the WalletPath
• blind: (for user) Blind 1NEW for address with the public key and random message
• deposit: (for bank) Use the TxHash to deposit NEW(decimal not counted)
• faucet: Get free money for address, only work for TestNet
• help: show help about any command
• info: (for bank) Show the info of the bank
• init: (for bank) Initialize config file for bank
• sign: (for bank) Sign blinded file for address of cash 1NEW with the private key
• unblind: (for user) Unblind 1NEW with the public key, unblinder and sig from the bank
• verify: (for bank) Verify unblinder sign file and send 1NEW to address
• version: Get version of NewCommander CLI

Example

Suppose Alice wants send 1NEW to Bob by the Bank,

Bank's address: 0x873054eacb22516e1dbc966c9ae338eef40fe15c

Alice's address: 0x97549E368AcaFdCAE786BB93D98379f1D1561a29

Bob's address: 0x2a8996eBb0314717dfdCd879685A9246649D7BC1

1. Bank: Create the RSA PEM file

   Generate an RSA keypair with a 2048 bit private key

   openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048

   Extracting the public key from an RSA keypair

   openssl rsa -pubout -in key.pem -out pubkey.pem

2. Bank: Initialize config file

   # Initialize config file
   NewChainBlind init

   Just press Enter to use the default configuration, and it's best to create a new user.

   Initialize config file
   Enter file in which to save (./config.toml):
   Enter the wallet storage directory (./wallet/):
   Enter NewChain json rpc or ipc url (https://rpc1.newchain.newtonproject.org):
   Enter path of Private Key RSA Pem file(./key.pem):
   Enter path of Public Key RSA Pem file(./pubkey.pem):
   Create a new bank account or not: [Y/n]
   Your new account is locked with a password. Please give a password. Do not forget this password.
   Enter passphrase (empty for no passphrase):
   Enter same passphrase again:
   0x873054eAcB22516E1dBC966C9aE338eef40FE15c
   Your configuration has been saved in  ./config.toml

3. Bank: Get the info of the bank

   NewChainBlind info

   then show the public key to all users

4. Alice: Deposit

   Use NewCommander pay to send 10 NEW to the address of bank, the send the sign tx hash to the bank

5. Bank: Check Alice deposit

   Use NewChainBlind deposit <txHash> to add the balance for Alice

   NewChainBlind deposit 0xfea3844616766cea49c21447d6e5a8c4521192b820c567bff81678615966987e

6. Alice: Blind

   Alice blind 1NEW with a random message and the bank public key

   # blind 1NEW, only support 1NEW
   NewChainBlind blind pubkey.pem

   the output of the cmd is as follow:

   Data:  20190511140547.data
   Blinded:  20190511140547.blinded
   Unblinder:  20190511140547.unblinder
   Send blinded file to bank

   the file is named with time-based random string, such as 20190511140547 in this example, Send 20190511140547.blinded to bank

7. Bank: Sign

   The Bank sign the blinded file *.blinded for Alice. The Bank will check the balance of Alice (the array of balances in config.toml) and sub 1NEW from the balance of the Alice's address

   # Sign the blinded file
   NewChainBlind sign 20190511140547.blinded 0x97549E368AcaFdCAE786BB93D98379f1D1561a29

   the output is as follow:

   Sub 1 NEW for 0x97549E368AcaFdCAE786BB93D98379f1D1561a29
   Current balance of 0x97549E368AcaFdCAE786BB93D98379f1D1561a29 is 59 NEW
   Sign:  20190511140547.blinded.sig
   Send signed blinded file back to user1

   then send the 20190511140547.blinded.sig back to the user

8. Alice: Unblind

   Alice un-blinds it by using pubkey.pem, *.blinded.sig and *.unblinder

   # Unblind with unblinder
   NewChainBlind unblind pubkey.pem 20190511140547.blinded.sig 20190511140547.unblinder

   the output is as follow:

   UnblinderSig:  20190511140547.unblinder.sig
   Send unblinder sig file and cash data to others

9. Alice Pay to Bob

   • when Alice pay 1NEW to Bob, just send him the file 20190511140547.unblinder.sig and 20190511140547.data
   • when Bob get the file, then him should send both of the file 20190511140547.unblinder.sig and 20190511140547.data to bank to verify it

10. Bank: Verify

    Verify unblinder and data, then send 1NEW to Bob

    # Verify unblinder and data, then send 1NEW to Bob's address
    NewChainBlind verify 20190511140547.unblinder.sig 20190511140547.data 0x2a8996eBb0314717dfdCd879685A9246649D7BC1

    if ok, then the bank pay 1 NEW to Bob's address on chain