Secret Keeper Application (#745)

- implement secret keeper demo
- readme
- create unit test mock rollback attack

---------

Signed-off-by: chenchanglew <chelew@student.ethz.ch>
Signed-off-by: chenchanglew <lewchenchang@gmail.com>

samples/chaincode/secret-keeper-go/.gitignore

@@ -0,0 +1,7 @@
+ecc
+ecc-bundle
+enclave.json
+private.pem
+public.pem
+mrenclave
+details.env

samples/chaincode/secret-keeper-go/Makefile

@@ -0,0 +1,9 @@
+# Copyright 2019 Intel Corporation
+# Copyright IBM Corp. All Rights Reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+TOP = ../../..
+include $(TOP)/ecc_go/build.mk
+
+CC_NAME ?= fpc-secret-keeper-go

samples/chaincode/secret-keeper-go/README.md

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+# Secret Keeper
+
+Secret Keeper is a demo application designed to securely store sensitive information, acting as a digital vault. It's ideal for users who need to manage access to shared secrets within a team or organization.
+
+## Functions
+
+Secret Keeper provides the following functionalities:
+
+- **InitSecretKeeper**: Initializes the application with default authorization and secret values. Intended for one-time use at application setup. Note: While potential misuse is considered low-risk, it's recommended to secure access to this function.
+
+- **RevealSecret**: Allows authorized users to view the currently stored secret.
+
+- **LockSecret**: Enables authorized users to update the secret value. This action replaces the existing secret.
+
+- **AddUser**: Permits authorized users to add a new user to the authorization list, granting them access to all functions.
+
+- **RemoveUser**: Allows authorized users to remove an existing user from the authorization list, revoking their access.
+
+## Example Usage
+
+To demonstrate Secret Keeper's capabilities, you can deploy the chaincode to [the-simple-testing-network](https://github.com/hyperledger/fabric-private-chaincode/tree/main/samples/deployment/fabric-smart-client/the-simple-testing-network) and then invoke it with the [simple-cli-go](https://github.com/hyperledger/fabric-private-chaincode/tree/main/samples/application/simple-cli-go).
+
+1. Initialize Secret Keeper:
+```
+./fpcclient invoke initSecretKeeper
+```
+2. Reveal the secret as Alice:
+```
+./fpcclient query revealSecret Alice
+```
+3. Change the secret as Bob:
+```
+./fpcclient invoke lockSecret Bob NewSecret
+```
+4. Attempt to reveal the secret as Alice (now updated):
+```
+./fpcclient query revealSecret Alice
+```
+5. Remove Bob's access as Alice:
+```
+./fpcclient invoke removeUser Alice Bob
+```
+6. Attempt to reveal the secret as Bob (should fail):
+```
+./fpcclient query revealSecret Bob // (will failed) 
+```
+7. Re-add Bob to the authorization list as Alice:
+```
+./fpcclient invoke addUser Alice Bob
+```
+8. Bob can now reveal the secret successfully:
+```
+./fpcclient query revealSecret Bob // (will success)
+```

samples/chaincode/secret-keeper-go/chaincode/secret-keeper.go

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+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package chaincode
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/hyperledger/fabric-contract-api-go/contractapi"
+)
+
+const OK = "OK"
+const AUTH_LIST_KEY = "AUTH_LIST_KEY"
+const SECRET_KEY = "SECRET_KEY"
+
+type SecretKeeper struct {
+	contractapi.Contract
+}
+
+type AuthSet struct {
+	Pubkey map[string]struct{}
+}
+
+type Secret struct {
+	Value string `json:"Value"`
+}
+
+func (t *SecretKeeper) InitSecretKeeper(ctx contractapi.TransactionContextInterface) error {
+	// init authSet
+	pubkeyset := make(map[string]struct{})
+	pubkeyset["Alice"] = struct{}{}
+	pubkeyset["Bob"] = struct{}{}
+	authSet := AuthSet{
+		Pubkey: pubkeyset,
+	}
+
+	authSetJson, err := json.Marshal(authSet)
+	if err != nil {
+		return err
+	}
+
+	err = ctx.GetStub().PutState(AUTH_LIST_KEY, authSetJson)
+	if err != nil {
+		return fmt.Errorf("failed to put %s to world state. %v", AUTH_LIST_KEY, err)
+	}
+
+	// init secret
+	secret := Secret{
+		Value: "DefaultSecret",
+	}
+
+	secretJson, err := json.Marshal(secret)
+	if err != nil {
+		return err
+	}
+
+	err = ctx.GetStub().PutState(SECRET_KEY, secretJson)
+	if err != nil {
+		return fmt.Errorf("failed to put %s to world state. %v", SECRET_KEY, err)
+	}
+
+	return nil
+}
+
+func (t *SecretKeeper) AddUser(ctx contractapi.TransactionContextInterface, sig string, pubkey string) error {
+	// check if the user allow to update authSet
+	valid, err := VerifySig(ctx, sig)
+	if err != nil {
+		return err
+	}
+	if !valid {
+		return fmt.Errorf("user are not allowed to perform this action")
+	}
+
+	// update the value
+	authSet, _ := GetAuthList(ctx)
+	authSet.Pubkey[pubkey] = struct{}{}
+
+	authSetJson, err := json.Marshal(authSet)
+	if err != nil {
+		return err
+	}
+
+	err = ctx.GetStub().PutState(AUTH_LIST_KEY, authSetJson)
+	if err != nil {
+		return fmt.Errorf("failed to put %s to world state. %v", AUTH_LIST_KEY, err)
+	}
+
+	return nil
+}
+
+func (t *SecretKeeper) RemoveUser(ctx contractapi.TransactionContextInterface, sig string, pubkey string) error {
+	// check if the user allow to update authSet
+	valid, err := VerifySig(ctx, sig)
+	if err != nil {
+		return err
+	}
+	if !valid {
+		return fmt.Errorf("user are not allowed to perform this action")
+	}
+
+	// update the value
+	authSet, _ := GetAuthList(ctx)
+	delete(authSet.Pubkey, pubkey)
+
+	authSetJson, err := json.Marshal(authSet)
+	if err != nil {
+		return err
+	}
+
+	err = ctx.GetStub().PutState(AUTH_LIST_KEY, authSetJson)
+	if err != nil {
+		return fmt.Errorf("failed to put %s to world state. %v", AUTH_LIST_KEY, err)
+	}
+
+	return nil
+}
+
+func (t *SecretKeeper) LockSecret(ctx contractapi.TransactionContextInterface, sig string, value string) error {
+	// check if the user allow to update secret
+	valid, err := VerifySig(ctx, sig)
+	if err != nil {
+		return err
+	}
+	if !valid {
+		return fmt.Errorf("user are not allowed to perform this action")
+	}
+
+	// update the value
+	newSecret := Secret{
+		Value: value,
+	}
+
+	newSecretJson, err := json.Marshal(newSecret)
+	if err != nil {
+		return err
+	}
+
+	err = ctx.GetStub().PutState(SECRET_KEY, newSecretJson)
+	if err != nil {
+		return fmt.Errorf("failed to put %s to world state. %v", SECRET_KEY, err)
+	}
+
+	return nil
+}
+
+func (t *SecretKeeper) RevealSecret(ctx contractapi.TransactionContextInterface, sig string) (*Secret, error) {
+	// check if the user allow to view the secret.
+	valid, err := VerifySig(ctx, sig)
+	if err != nil {
+		return nil, err
+	}
+	if !valid {
+		return nil, fmt.Errorf("user are not allowed to perform this action")
+	}
+
+	// reveal secret
+	secretJson, err := ctx.GetStub().GetState(SECRET_KEY)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read from world state: %v", err)
+	}
+	if secretJson == nil {
+		return nil, fmt.Errorf("the asset %s does not exist", SECRET_KEY)
+	}
+	var secret Secret
+	err = json.Unmarshal(secretJson, &secret)
+	if err != nil {
+		return nil, err
+	}
+	return &secret, nil
+}
+
+func GetAuthList(ctx contractapi.TransactionContextInterface) (*AuthSet, error) {
+	authSetJson, err := ctx.GetStub().GetState(AUTH_LIST_KEY)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read from world state: %v", err)
+	}
+	if authSetJson == nil {
+		return nil, fmt.Errorf("the asset %s does not exist", AUTH_LIST_KEY)
+	}
+
+	var authSet AuthSet
+	err = json.Unmarshal(authSetJson, &authSet)
+	if err != nil {
+		return nil, err
+	}
+	return &authSet, nil
+}
+
+func VerifySig(ctx contractapi.TransactionContextInterface, sig string) (bool, error) {
+	authSet, err := GetAuthList(ctx)
+	if err != nil {
+		return false, err
+	}
+
+	if _, exist := authSet.Pubkey[sig]; exist {
+		return true, nil
+	}
+
+	return false, nil
+}