I am a newbie to Hyperledger Fabric. I came across a very confusing part of fabric.
Cryptogen is used to generate certs and keys for users and admin in an organisation.
Talking specifically about fabcar,
A very similar thing is the done by:
enrolling an admin
enrolling and registering a user identity using CA, in fabcar chaincode.
Things got more confusing when I saw CA server creating a bootstrap
'admin' identity while starting of the container itself.
So what exactly is happening?
What is the flow?
What is the difference between these admins created again and again?
I see, CA server container has a volume mounted, pointing back to the crypto-config folder which already have certs and keys generated by cryptogen.
Why are we again creating bootstrap identity on fabric-ca-server start using -b flag? We already have admin certs and keys generated for admin by cryptogen and those are already mounted on the fabric ca server container.
Why are we again enrolling an admin in fabcar chaincode, we already have certs and keys for admin, don't we(from the volumes mounted on fabric ca server container)?
Why are we both registering and enrolling a new user in fabcar chaincode, we already have certs and keys for one user(in fabcar), don't we(from the volumes mounted on fabric ca server container)?
Similar existing answers is not what I am looking for. I want an in-depth insight.
Thanks.
Okay, so after digging around for continuous 1 week I found exact answer to the question.
First, I would like to lay down exact flow and structure of fabric samples applications.
Fabcar and Commercial Paper are two different applications being
provided by fabric as a part of fabric sample.
Fabcar uses first-network and Commercial Paper uses basic-network.
Fabcar has its chaincodes in chaincode folder while Commercial Paper has its chaincodes in contract folder within the two organisations.
After chaincodes are installed by administrators (don't confuse this admin with CA admin, this is simply a developer who is managing channel) using peer chaincode install and peer chaincode instantiate the contract becomes available to all the components of the respective channels.
Now we need to have certain application that will be invoking contracts known to the channel. Both Fabcar and Commercial Paper have their different applications in their respective application folders.
Applications can interact with our channel or say underlying fabric layer through a gateway.
The Hyperledger Fabric SDK provides a gateway abstraction so that
applications can focus on application logic while delegating network
interaction to the gateway. Gateways and wallets make it
straightforward to write Hyperledger Fabric applications. Find here in the docs
Our applications require some identity to be able to use underlying fabric layer. This identity's authenticity is checked by gateway before allowing access to the network.
Fabric uses concept of keys and signed certificates to perform this authentication.
Diving into a different concept here, fabric provides two kind of certification architectures (architecture might not be the correct word),
cryptogen - generally used for developement or testing purposes to generate keys and certificates
Certificate Authority - not a new concept, used by fabric to generate certificates. Any CA server requires to have admin to allow generating certificates.
While bringing up the server itself, this bootstrap identity is created using fabric-ca-server start with a -b option with username:password parameter.
Coming back to fabric, before starting any network (basic-network or first-network) fabric asks us to generate cryto-config.
Commercial Paper uses certificates and keys generated by this previously generated crypto-config by cryptogen to generate identities for the application.
Fabcar uses CA to generate certificates and keys. Admin was registered already when we brought up our CA server container in Fabcar. We simply gave him certs and keys on enrollment. New user require both registration and enrollment (done using CA admin identity).
The private and public key are first generated locally and the public
key is then sent to the CA which returns an encoded certificate for
use by the application. These three credentials are then stored in the
wallet, allowing us to act as an administrator for the CA. Find here in the docs
So it's not by design of fabric why Fabcar used CA and why Commercial-Paper used cryptogen, it's simply by choice.
I'll end my answer, quoting exact statement from the fabric documentation.
When we created the network, an admin user literally called admin
was created as the registrar for the certificate authority (CA).
Our first step is to generate the private key, public key, and X.509
certificate for admin using the enroll.js program. This process uses
a Certificate Signing Request (CSR) — the private and public key are
first generated locally and the public key is then sent to the CA
which returns an encoded certificate for use by the application.
These three credentials are then stored in the wallet, allowing us
to act as an administrator for the CA. We will subsequently register
and enroll a new application user which will be used by our
application to interact with the blockchain. Find here in the docs
addToWallet.js is the program that Isabella is going to use to load
her identity into her wallet, and issue.js will use this identity to
create commercial paper 00001 on behalf of MagnetoCorp by invoking
papercontract. Find here in the docs
Any corrections from experts are very welcome. These are my deductions from code observation.
I don't know what fabcar does, but maybe I can clarify some Hyperledger Fabric concepts to you.
cryptogen is a development tool using for generating all the (MSP and TLS related) cryptographic stuff you need initially for your development Fabric network.
For more serious deployments, you use Fabric-CA instead. Fabric-CA is a Certification Authority that maintains a database of the identities registered for your organization and allow your registered actors to enroll their certificates. You can also update identities, revoke identities and certificates, etc.
And then you have to distinguish a CA administrator from a organization administrator. You first enroll the CA administrator, otherwise you cannot register identities. And a organization admin is simply an identity with role admin for the organization.
Normally, the enrolled CA administrator generates all the identities. After that, later, in other place, the organization administrator (or any other identity) enrolls its certificate by specifying the user and password declared during registration.
Some Theory: cryptogen is just a tool written in golang and what it does is it will create a self-signed root ca and some signed certificates(org admin, users, entities)
Now when you start CA, if you want to use the same cert and key generated by cryptogen then you will use below command
fabric-ca-server start -b myorgadmin:myorgpw -d
ELSE if you do not want to use cryptogen generated certificates then you can use below command and you should forget about cryptogen generated certificates because they no longer use and you have to generate by yourself
fabric-ca-server init -b myorgadmin:myorgpw
DIFFERENCE is init command
Bootstrap CA server credentials are in order to authenticate for future
purposes
Ex: If you want to register a new user then you need to authenticate
with credentials
In future, you can use cryptogen generated user certificates or you can register different users by authenticating CA server
I am trying to understand why hyperledger cryptogen tool creates admin user by default for organiztion, because, when I am using sdk, I have to create p/k for user and make enroll request to organization's ca, and it gives me signed cert for user or admin and with this user I can invoke some transactions or make peer to join channel (if this user is admin) or etc. So for what reason should I use default admin user, what is a purpose of default admin?
If there is no admin, then who will register and enroll users? If you are able to enroll users without default admin generated by cryptogen, then go for it! You don't need default admin in that case.
Also note that cryptogen should not be used in production. From official docs:
It would normally not be used in the operation of a production
network.
Adding some more details as to why cryptogen would not be used in production. As I understand, Its not that the tool lacks some functionality. But it wouldn't be used in production because:
Copying the secrets over to a remote server is less than ideal. This can be prevented by running cryptogen on the server. So there is a solution around this problem.
The real reason why cryptogen would not be used in production is because how would one dynamically register and enroll users? Cryptogen can be used to register a known set of users prior to launching the network, but think about how you would sign up new users? For that you need fabric-ca.
I think Fabric CA is needed when client node has to enroll for using Node.js Application. So if I use Fabric-cli when I invoke or queries chaincode, does Fabric CA need?
-> I thinking Fabric CA only useful for enrolling client node. And If client node does not exist in a network, Fabric CA can be replaced with Cryptogen Tool.
To be able to do invokes and queries you need a user context. To get the user context you either need an user created by registering and enrolling an user via the CA server or you can use an already created user by the cryptogen tool.
So point is, once the user is created, you no longer need the CA Server or crytogen tool.
In fact cryptogen tool is used to generate the certs of the entire network when the network is not created in the first place.
Also, when T-Certs will be supported in the future, for each transaction that you make, you would be required to get a T-Cert from the CA server to proceed with the transaction.
.hfc-key-store wallet used by HFC SDK uses user certificates generated by Fabric-CA to connect to Fabric platform.
Is there a way to generate these certificates without Fabric-CA?
I assume it would involve re-purposing of Org user certificates generated by cryptogen. However, I would appreciate if someone can point me to a documentation that tells how to do it.
I went through documentation on fabric-ca
http://hyperledger-fabric-ca.readthedocs.io/en/latest/users-guide.html
I have below questions
1.When will be fabric-ca come into picture in hyperperledger for user authentication or in msp certs generation or in both
Can we use some other third party CA in place of fabric-ca
What should be the things to be kept in mind if we use some third party CA.
Is there any sample to understand it more(already went through balance-transfer)
fabric-ca comes into the picture for both authentication and MSP certs generation. The /enroll API requires basic authentication, and assuming success, will issue an enrollment certificate and populate the appropriate MSP directories.
You have the following choices when it comes to using a CA with fabric:
a) Use fabric CA to function as a root CA and/or intermediate CA.
b) Start fabric CA with an intermediate signing certificate which you
get from an external CA.
c) Don't use fabric CA at all and use an external CA completely.
With a & b, the fabric CA server can function as its own user registry,
or it can talk to an LDAP server as the user registry.
3) When using a 3rd party CA (#c above), you will need to think about
how you want to do access control in chaincode. One option is based
on the OU (Organizational Units) that a user's certificate has, which
means the 3rd party CA will need to be able to restrict which OU
values are issued to which users. When using the fabric CA server
to issue certificates, you can use Attribute-Based Access Control
(ABAC) to perform access control for chaincode.
4) There is a sample which is not merged yet at https://gerrit.hyperledger.org/r/#/c/13213/.
See the README.md for a description of how to run the sample and
an overview of how it works.