Add account-based token sample (go chaincode) (#318)

Add an account-based token sample go chaincode, as well as an associated readme tutorial. Signed-off-by: David Enyeart <enyeart@us.ibm.com>
2026-06-17 15:35:09 +00:00 · 2020-10-14 02:26:38 -04:00 · 2020-10-14 02:26:38 -04:00 · fa0529c393
commit fa0529c393
parent e7189fc62a
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--- a/token-account-based/README.md
+++ b/token-account-based/README.md
@ -0,0 +1,202 @@
+# Account-based token scenario
+
+The account-based token smart contract demonstrates how to create and transfer fungible tokens using an account-based model. In an account-based model, there is an account for each participant that holds a balance of tokens.
+A mint transaction creates tokens in an account, while a transfer transaction debits the caller's account and credits another account.
+
+In this sample it is assumed that only one organization (played by Org1) is in a central banker role and can mint new tokens into their account, while any organization can transfer tokens from their account to a recipient's account.
+Accounts could be defined at the organization level or client identity level. In this sample accounts are defined at the client identity level, where every authorized client with an enrollment certificate from their organization implicitly has an account ID that matches their client ID.
+The client ID is simply a base64-encoded concatenation of the issuer and subject from the client identity's enrollment certificate. The client ID can therefore be considered the account ID that is used as the payment address of a recipient.
+
+In this tutorial, you will mint and transfer tokens as follows:
+
+- A member of Org1 uses the `Mint` function to create new tokens into their account. The `Mint` function reads the certificate information of the client identity that submitted the transaction using the `GetClientIdentity.GetID()` API and credits the account associated with the client ID with the requested number of tokens.
+- The same minter client will then use the `Transfer` function to transfer the requested number of tokens to the recipient's account. It is assumed that the recipient has provided their account ID to the transfer caller out of band. The recipient can then transfer tokens to other registered users in the same fashion.
+
+## Bring up the test network
+
+You can run the account-based token transfer scenario using the Fabric test network. Open a command terminal and navigate to the test network directory in your local clone of the `fabric-samples`. We will operate from the `test-network` directory for the remainder of the tutorial.
+```
+cd fabric-samples/test-network
+```
+
+Run the following command to start the test network:
+```
+./network.sh up createChannel -ca
+```
+
+The test network is deployed with two peer organizations. The `createChannel` flag deploys the network with a single channel named `mychannel` with Org1 and Org2 as channel members.
+The -ca flag is used to deploy the network using certificate authorities. This allows you to use each organization's CA to register and enroll new users for this tutorial.
+
+## Deploy the smart contract to the channel
+
+You can use the test network script to deploy the account-based token contract to the channel that was just created. Deploy the smart contract to `mychannel` using the following command:
+```
+./network.sh deployCC -ccn token_account -ccp ../token-account-based/chaincode-go/
+```
+
+The above command deploys the go chaincode with short name `token_account`. The smart contract will use the default endorsement policy of majority of channel members.
+Since the channel has two members, this implies that we'll need to get peer endorsements from 2 out of the 2 channel members.
+
+Now you are ready to call the deployed smart contract via peer CLI calls. But let's first create the client identities for our scenario.
+
+## Register identities
+
+The smart contract supports accounts owned by individual client identities from organizations that are members of the channel. In our scenario, the minter of the tokens will be a member of Org1, while the recipient will belong to Org2. To highlight the connection between the `GetClientIdentity().GetID()` API and the information within a user's certificate, we will register two new identities using the Org1 and Org2 Certificate Authorities (CA's), and then use the CA's to generate each identity's certificate and private key.
+
+First, we need to set the following environment variables to use the the Fabric CA client (and subsequent commands).
+```
+export PATH=${PWD}/../bin:${PWD}:$PATH
+export FABRIC_CFG_PATH=$PWD/../config/
+```
+
+The terminal we have been using will represent Org1. We will use the Org1 CA to create the minter identity. Set the Fabric CA client home to the MSP of the Org1 CA admin (this identity was generated by the test network script):
+```
+export FABRIC_CA_CLIENT_HOME=${PWD}/organizations/peerOrganizations/org1.example.com/
+```
+
+You can register a new minter client identity using the `fabric-ca-client` tool:
+```
+fabric-ca-client register --caname ca-org1 --id.name minter --id.secret minterpw --id.type client --tls.certfiles ${PWD}/organizations/fabric-ca/org1/tls-cert.pem
+```
+
+You can now generate the identity certificates and MSP folder by providing the enroll name and secret to the enroll command:
+```
+fabric-ca-client enroll -u https://minter:minterpw@localhost:7054 --caname ca-org1 -M ${PWD}/organizations/peerOrganizations/org1.example.com/users/minter@org1.example.com/msp --tls.certfiles ${PWD}/organizations/fabric-ca/org1/tls-cert.pem
+```
+
+Run the command below to copy the Node OU configuration file into the minter identity MSP folder.
+```
+cp ${PWD}/organizations/peerOrganizations/org1.example.com/msp/config.yaml ${PWD}/organizations/peerOrganizations/org1.example.com/users/minter@org1.example.com/msp/config.yaml
+```
+
+Open a new terminal to represent Org2 and navigate to /fabric-samples/test-network. We'll use the Org2 CA to create the Org2 recipient identity. Set the Fabric CA client home to the MSP of the Org2 CA admin:
+```
+cd fabric-samples/test-network
+export FABRIC_CA_CLIENT_HOME=${PWD}/organizations/peerOrganizations/org2.example.com/
+```
+
+You can register a recipient client identity using the `fabric-ca-client` tool:
+```
+fabric-ca-client register --caname ca-org2 --id.name recipient --id.secret recipientpw --id.type client --tls.certfiles ${PWD}/organizations/fabric-ca/org2/tls-cert.pem
+```
+
+We can now enroll to generate the identity certificates and MSP folder:
+```
+fabric-ca-client enroll -u https://recipient:recipientpw@localhost:8054 --caname ca-org2 -M ${PWD}/organizations/peerOrganizations/org2.example.com/users/recipient@org2.example.com/msp --tls.certfiles ${PWD}/organizations/fabric-ca/org2/tls-cert.pem
+```
+
+Run the command below to copy the Node OU configuration file into the recipient identity MSP folder.
+```
+cp ${PWD}/organizations/peerOrganizations/org2.example.com/msp/config.yaml ${PWD}/organizations/peerOrganizations/org2.example.com/users/recipient@org2.example.com/msp/config.yaml
+```
+
+## Mint some tokens
+
+Now that we have created the identity of the minter, we can invoke the smart contract to mint some tokens.
+Shift back to the Org1 terminal, we'll set the following environment variables to operate the `peer` CLI as the minter identity from Org1.
+```
+export CORE_PEER_TLS_ENABLED=true
+export CORE_PEER_LOCALMSPID="Org1MSP"
+export CORE_PEER_MSPCONFIGPATH=${PWD}/organizations/peerOrganizations/org1.example.com/users/minter@org1.example.com/msp
+export CORE_PEER_TLS_ROOTCERT_FILE=${PWD}/organizations/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/ca.crt
+export CORE_PEER_ADDRESS=localhost:7051
+export TARGET_TLS_OPTIONS="-o localhost:7050 --ordererTLSHostnameOverride orderer.example.com --tls --cafile ${PWD}/organizations/ordererOrganizations/example.com/orderers/orderer.example.com/msp/tlscacerts/tlsca.example.com-cert.pem --peerAddresses localhost:7051 --tlsRootCertFiles ${PWD}/organizations/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/ca.crt --peerAddresses localhost:9051 --tlsRootCertFiles ${PWD}/organizations/peerOrganizations/org2.example.com/peers/peer0.org2.example.com/tls/ca.crt"
+```
+
+The last environment variable above will be utilized within the CLI invoke commands to set the target peers for endorsement, and the target ordering service endpoint and TLS options.
+
+We can then invoke the smart contract to mint 5000 tokens:
+```
+peer chaincode invoke $TARGET_TLS_OPTIONS -C mychannel -n token_account -c '{"function":"Mint","Args":["5000"]}'
+```
+
+The mint function validated that the client is a member of the minter organization, and then credited the minter client's account with 5000 tokens. We can check the minter client's account balance by calling the `ClientAccountBalance` function.
+```
+peer chaincode query -C mychannel -n token_account -c '{"function":"ClientAccountBalance","Args":[]}'
+```
+
+The function queries the balance of the account associated with the minter client ID and returns:
+```
+5000
+```
+
+## Transfer tokens
+
+The minter intends to transfer 100 tokens to the Org2 recipient, but first the Org2 recipient needs to provide their own account ID as the payment address.
+A client can derive their account ID from their own public certificate, but to be sure the account ID is accurate, the contract has a `ClientAccountID` utility function that simply looks at the callers certificate and returns the calling client's ID, which will be used as the account ID.
+Let's prepare the Org2 terminal by setting the environment variables for the Org2 recipient user.
+```
+export PATH=${PWD}/../bin:${PWD}:$PATH
+export FABRIC_CFG_PATH=$PWD/../config/
+export CORE_PEER_TLS_ENABLED=true
+export CORE_PEER_LOCALMSPID="Org2MSP"
+export CORE_PEER_MSPCONFIGPATH=${PWD}/organizations/peerOrganizations/org2.example.com/users/recipient@org2.example.com/msp
+export CORE_PEER_TLS_ROOTCERT_FILE=${PWD}/organizations/peerOrganizations/org2.example.com/peers/peer0.org2.example.com/tls/ca.crt
+export CORE_PEER_ADDRESS=localhost:9051
+```
+
+Using the Org2 terminal, the Org2 recipient user can retrieve their own account ID:
+```
+peer chaincode query -C mychannel -n token_account -c '{"function":"ClientAccountID","Args":[]}'
+```
+
+The function returns of recipient's account ID:
+```
+eDUwOTo6Q049cmVjaXBpZW50LE9VPWNsaWVudCxPPUh5cGVybGVkZ2VyLFNUPU5vcnRoIENhcm9saW5hLEM9VVM6OkNOPWNhLm9yZzIuZXhhbXBsZS5jb20sTz1vcmcyLmV4YW1wbGUuY29tLEw9SHVyc2xleSxTVD1IYW1wc2hpcmUsQz1VSw==
+```
+
+Let's base64 decode the account ID to make sure it represents the Org2 recipient user:
+```
+echo eDUwOTo6Q049cmVjaXBpZW50LE9VPWNsaWVudCxPPUh5cGVybGVkZ2VyLFNUPU5vcnRoIENhcm9saW5hLEM9VVM6OkNOPWNhLm9yZzIuZXhhbXBsZS5jb20sTz1vcmcyLmV4YW1wbGUuY29tLEw9SHVyc2xleSxTVD1IYW1wc2hpcmUsQz1VSw== | base64 --decode
+```
+
+The result shows that the subject and issuer is indeed the recipient user from Org2:
+```
+x509::CN=recipient,OU=client,O=Hyperledger,ST=North Carolina,C=US::CN=ca.org2.example.com,O=org2.example.com,L=Hursley,ST=Hampshire,C=UK
+```
+
+After the Org2 recipient provides their account ID to the minter, the minter can initiate a transfer from their account to the recipient's account.
+Back in the Org1 terminal, request the transfer of 100 tokens to the recipient account:
+```
+peer chaincode invoke $TARGET_TLS_OPTIONS -C mychannel -n token_account -c '{"function":"Transfer","Args":[ "eDUwOTo6Q049cmVjaXBpZW50LE9VPWNsaWVudCxPPUh5cGVybGVkZ2VyLFNUPU5vcnRoIENhcm9saW5hLEM9VVM6OkNOPWNhLm9yZzIuZXhhbXBsZS5jb20sTz1vcmcyLmV4YW1wbGUuY29tLEw9SHVyc2xleSxTVD1IYW1wc2hpcmUsQz1VSw==","100"]}'
+```
+
+The `Transfer` function validates that the account associated with the calling client ID has sufficient funds for the transfer.
+It will then debit the caller's account and credit the recipient's account. Note that the sample contract will automatically create an account with zero balance for the recipient, if one does not yet exist.
+
+While still in the Org1 terminal, let's request the minter's account balance again:
+```
+peer chaincode query -C mychannel -n token_account -c '{"function":"ClientAccountBalance","Args":[]}'
+```
+
+The function queries the balance of the account associated with the minter client ID and returns:
+```
+4900
+```
+
+And then using the Org2 terminal, let's request the recipient's balance:
+```
+peer chaincode query -C mychannel -n token_account -c '{"function":"ClientAccountBalance","Args":[]}'
+```
+
+The function queries the balance of the account associated with the recipient client ID and returns:
+```
+100
+```
+
+Congratulations, you've transferred 100 tokens! The Org2 recipient can now transfer tokens to other registered users in the same manner.
+
+## Clean up
+
+When you are finished, you can bring down the test network. The command will remove all the nodes of the test network, and delete any ledger data that you created:
+```
+./network.sh down
+```
+
+## Contract extension ideas
+
+You can extend the basic account-based token sample to meet other requirements. For example:
+
+* Rather than using the default 'majority' endorsement policy, you could set the endorsement policy to a subset of organizations that represent trust anchors for the contract execution.
+* You could also require that accounts get setup before use, and apply state-based endorsement for each account key that has been created. For example on an OrgA account, set state-based endorsement policy to be OrgA and the central banker (or some other trust anchor). And on an OrgB account, set state-based endorsement policy to be OrgB and the central banker (or some other trust anchor). Then to transfer tokens from an OrgA account to an OrgB account, you would require endorsements from OrgA, OrgB, and the central banker (or some other trust anchor).
+* You could utilize anonymous addresses for accounts based on private-public key pairs, instead of accounts keyed by the client ID. In order to spend the tokens, the client would have to sign the transfer input as proof that they own the address private key, which the contract would then validate, similar to the Ethereum model in the permissionless blockchain space. However, in a permissioned blockchain such as Fabric, only registered clients are authorized to participate. Furthermore, if you don't want to leak the registered client identity associated with each account, the clients could be registered using an Identity Mixer MSP, so that the client itself is also anonymous in each of the token transactions.
--- a/token-account-based/chaincode-go/chaincode/token_contract.go
+++ b/token-account-based/chaincode-go/chaincode/token_contract.go
@ -0,0 +1,174 @@
+package chaincode
+
+import (
+	"fmt"
+	"log"
+	"strconv"
+
+	"github.com/hyperledger/fabric-contract-api-go/contractapi"
+)
+
+// SmartContract provides functions for transferring tokens between accounts
+type SmartContract struct {
+	contractapi.Contract
+}
+
+// Mint creates new tokens and adds them to minter's account balance
+func (s *SmartContract) Mint(ctx contractapi.TransactionContextInterface, amount int) error {
+
+	// Check minter authorization - this sample assumes Org1 is the central banker with privilege to mint new tokens
+	clientMSPID, err := ctx.GetClientIdentity().GetMSPID()
+	if err != nil {
+		return fmt.Errorf("failed to get MSPID: %v", err)
+	}
+	if clientMSPID != "Org1MSP" {
+		return fmt.Errorf("client is not authorized to mint new tokens")
+	}
+
+	// Get ID of submitting client identity
+	minter, err := ctx.GetClientIdentity().GetID()
+	if err != nil {
+		return fmt.Errorf("failed to get client id: %v", err)
+	}
+
+	if amount <= 0 {
+		return fmt.Errorf("mint amount must be a positive integer")
+	}
+
+	currentBalanceBytes, err := ctx.GetStub().GetState(minter)
+	if err != nil {
+		return fmt.Errorf("failed to read minter account %s from world state: %v", minter, err)
+	}
+
+	var currentBalance int
+
+	// If minter current balance doesn't yet exist, we'll create it with a current balance of 0
+	if currentBalanceBytes == nil {
+		currentBalance = 0
+	} else {
+		currentBalance, _ = strconv.Atoi(string(currentBalanceBytes)) // Error handling not needed since Itoa() was used when setting the account balance, guaranteeing it was an integer.
+	}
+
+	updatedBalance := currentBalance + amount
+
+	err = ctx.GetStub().PutState(minter, []byte(strconv.Itoa(updatedBalance)))
+	if err != nil {
+		return err
+	}
+
+	log.Printf("minter account %s balance updated from %d to %d", minter, currentBalance, updatedBalance)
+
+	return nil
+}
+
+// Transfer transfers tokens from client account to recipient account.
+// recipient account must be a valid clientID as returned by the ClientID() function.
+func (s *SmartContract) Transfer(ctx contractapi.TransactionContextInterface, recipient string, amount int) error {
+
+	if amount < 0 { // transfer of 0 is allowed in ERC20, so just validate against negative amounts
+		return fmt.Errorf("transfer amount cannot be negative")
+	}
+
+	// Get ID of submitting client identity
+	clientID, err := ctx.GetClientIdentity().GetID()
+	if err != nil {
+		return fmt.Errorf("failed to get client id: %v", err)
+	}
+
+	clientCurrentBalanceBytes, err := ctx.GetStub().GetState(clientID)
+	if err != nil {
+		return fmt.Errorf("failed to read client account %s from world state: %v", clientID, err)
+	}
+
+	if clientCurrentBalanceBytes == nil {
+		return fmt.Errorf("client account %s has no balance", clientID)
+	}
+
+	clientCurrentBalance, _ := strconv.Atoi(string(clientCurrentBalanceBytes)) // Error handling not needed since Itoa() was used when setting the account balance, guaranteeing it was an integer.
+
+	if clientCurrentBalance < amount {
+		return fmt.Errorf("client account %s has insufficient funds", clientID)
+	}
+
+	recipientCurrentBalanceBytes, err := ctx.GetStub().GetState(recipient)
+	if err != nil {
+		fmt.Errorf("failed to read recipient account %s from world state: %v", recipient, err)
+	}
+
+	var recipientCurrentBalance int
+	// If recipient current balance doesn't yet exist, we'll create it with a current balance of 0
+	if recipientCurrentBalanceBytes == nil {
+		recipientCurrentBalance = 0
+	} else {
+		recipientCurrentBalance, _ = strconv.Atoi(string(recipientCurrentBalanceBytes)) // Error handling not needed since Itoa() was used when setting the account balance, guaranteeing it was an integer.
+	}
+
+	clientUpdatedBalance := clientCurrentBalance - amount
+	recipientUpdatedBalance := recipientCurrentBalance + amount
+
+	err = ctx.GetStub().PutState(clientID, []byte(strconv.Itoa(clientUpdatedBalance)))
+	if err != nil {
+		return err
+	}
+
+	err = ctx.GetStub().PutState(recipient, []byte(strconv.Itoa(recipientUpdatedBalance)))
+	if err != nil {
+		return err
+	}
+
+	log.Printf("client %s balance updated from %d to %d", clientID, clientCurrentBalance, clientUpdatedBalance)
+	log.Printf("recipient %s balance updated from %d to %d", recipient, recipientCurrentBalance, recipientUpdatedBalance)
+
+	return nil
+}
+
+// BalanceOf returns the balance of the given account
+func (s *SmartContract) BalanceOf(ctx contractapi.TransactionContextInterface, account string) (int, error) {
+	balanceBytes, err := ctx.GetStub().GetState(account)
+	if err != nil {
+		return 0, fmt.Errorf("failed to read from world state: %v", err)
+	}
+	if balanceBytes == nil {
+		return 0, fmt.Errorf("the account %s does not exist", account)
+	}
+
+	balance, _ := strconv.Atoi(string(balanceBytes)) // Error handling not needed since Itoa() was used when setting the account balance, guaranteeing it was an integer.
+
+	return balance, nil
+}
+
+// ClientAccountBalance returns the balance of the requesting client's account
+func (s *SmartContract) ClientAccountBalance(ctx contractapi.TransactionContextInterface) (int, error) {
+
+	// Get ID of submitting client identity
+	clientID, err := ctx.GetClientIdentity().GetID()
+	if err != nil {
+		return 0, fmt.Errorf("failed to get client id: %v", err)
+	}
+
+	balanceBytes, err := ctx.GetStub().GetState(clientID)
+	if err != nil {
+		return 0, fmt.Errorf("failed to read from world state: %v", err)
+	}
+	if balanceBytes == nil {
+		return 0, fmt.Errorf("the account %s does not exist", clientID)
+	}
+
+	balance, _ := strconv.Atoi(string(balanceBytes)) // Error handling not needed since Itoa() was used when setting the account balance, guaranteeing it was an integer.
+
+	return balance, nil
+}
+
+// ClientAccountID returns the id of the requesting client's account.
+// In this implementation, the client account ID is the clientId itself.
+// Users can use this function to get their own account id, which they can then give to others as the payment address
+func (s *SmartContract) ClientAccountID(ctx contractapi.TransactionContextInterface) (string, error) {
+
+	// Get ID of submitting client identity
+	clientAccountID, err := ctx.GetClientIdentity().GetID()
+	if err != nil {
+		return "", fmt.Errorf("failed to get client id: %v", err)
+	}
+
+	return clientAccountID, nil
+}
--- a/token-account-based/chaincode-go/go.mod
+++ b/token-account-based/chaincode-go/go.mod
@ -0,0 +1,5 @@
+module github.com/hyperledger/fabric-samples/token-account-based/chaincode-go
+
+go 1.14
+
+require github.com/hyperledger/fabric-contract-api-go v1.1.0
--- a/token-account-based/chaincode-go/go.sum
+++ b/token-account-based/chaincode-go/go.sum
@ -0,0 +1,145 @@
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--- a/token-account-based/chaincode-go/token_account_based.go
+++ b/token-account-based/chaincode-go/token_account_based.go
@ -0,0 +1,23 @@
+/*
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package main
+
+import (
+	"log"
+
+	"github.com/hyperledger/fabric-contract-api-go/contractapi"
+	"github.com/hyperledger/fabric-samples/token-account-based/chaincode-go/chaincode"
+)
+
+func main() {
+	tokenChaincode, err := contractapi.NewChaincode(&chaincode.SmartContract{})
+	if err != nil {
+		log.Panicf("Error creating token-account-based chaincode: %v", err)
+	}
+
+	if err := tokenChaincode.Start(); err != nil {
+		log.Panicf("Error starting token-account-based chaincode: %v", err)
+	}
+}