How do I get and use the public/private keys of users in Hyperledger v1.0?

Question

I read that in Hyperledger v1, encryption and channels can be used to enforce privacy.

I want to try the encryption approach to accomplish this. Since all registered users have private/public keys, I plan to use the public keys of users to encrypt some data (later I plan to combine this with symmetric cryptography to make it more efficient).

In addition, I plan to use the private key of the invoker of a function to perform decryption.

How do I get the public/private keys inside the chaincode? In addition, I also plan to perform encryption/decryption in NodeJS (outside the chaincode) since I'm using the NodeJS SDK for Hyperledger v1. How do I get the public/private keys through NodeJS?

Answer 1

While using NodeSDK you simply load keys from theirs location on disk and to obtain signer (client) certificate you can use API from ChaincodeStubInterface interface which provided you while chaincode is invoked:

// GetCreator returns `SignatureHeader.Creator` (e.g. an identity)
// of the `SignedProposal`. This is the identity of the agent (or user)
// submitting the transaction.
GetCreator() ([]byte, error)

Answer 2

First of all, I think that you should know how are those keys created. There are different ways for it, but Hyperledger Fabric gives you two tools to create these keys:

• Cryptogen: this tool is used to generate the cryptographic material (x509 certs) for your network entities. These certificates are representative of identities, and they allow for sign/verify authentication to take place as our entities communicate and transact.
• Fabric CA: a component of the Fabric, ie the CA that will issue certificates for each member.

Then, once you have the keys, you should manage them. The Fabric project makes it easier thanks to the MSP . When you create a channel, you define the public keys of the peers and the keys of the issuers of those certificates. Then, Fabric manages them to verify the transactions.

The Membership service provider (MSP) offers us the possibility of abstracting from all the cryptographic mechanisms and protocols of validation, authentication verification and signature.