fabric-ca

Fabric CA

The fabric-ca is a Certificate Authority for Hyperledger Fabric v1.0 and later.

It consists of both a serve and a client component.

It provides features including:

• registration of identities;
• enrollment of identities and issuance of enrollment certificates (ECerts);
• issuance of transaction certificates (TCerts) given proof of ownership of an ECert;
• certificate renewal and revocation.

See the Fabric-CA design doc for design documentation.

Getting Started

Prerequisites

• Go 1.7+ installation or later
• GOPATH environment variable is set correctly
• In this document, FABRIC_CA refers to the $GOPATH/src/github.com/hyperledger/fabric-ca directory

Install fabric-ca

To install fabric-ca, simply type:

# go get github.com/hyperledger/fabric-ca

For fabric-ca developers, you may do as follows to clone and build:

# mkdir -p $GOPATH/src/github.com/hyperledger
# cd $GOPATH/src/github.com/hyperledger
# git clone ssh://[email protected]:29418/fabric-ca
# cd fabric-ca
# make

See the Makefile for various build targets and their descriptions.

Explore the fabric-ca CLI

The following shows the fabric-ca usage message:

# fabric-ca
fabric-ca client       - client related commands
fabric-ca server       - server related commands
fabric-ca cfssl        - all cfssl commands

For help, type "fabric-ca client", "fabric-ca server", or "fabric-ca cfssl".

The fabric-ca client and server commands are what you will use. However, since fabric-ca is built on top of CFSSL and CFSSL has its own CLI, you may issue any cfssl command with the fabric-ca cfssl command prefix.

fabric-ca server configuration options

tls_disable (Default: false) - Setting to true will disable TLS

max_enrollments (Default: 0) - Allows you to specify how many times a user can use its one time password to enroll itself. Default is 0, allows for unlimited enrollments.

Initialize the fabric-ca server

Executing the following fabric-ca command will generate a private key and self-signed x509 certificate to start the fabric-ca server in the Start the fabric-ca server section. These two PEM files will be generated and stored in the directory $FABRIC_CA_HOME: server-cert.pem and server-key.pem. They can be used as input parameters to -ca and -ca-key in the command to start the fabric-ca server.

# fabric-ca server init ../testdata/csr_dsa.json

The ../testdata/csr_dsa.json file can be customized to generate x509 certificates and keys that support both RSA and Elliptic Curve (ECDSA).

The following setting is an example of the implementation of Elliptic Curve Digital Signature Algorithm (ECDSA) with curve: secp384r1 and Signature Algorithm: ecdsa-with-SHA384:

"algo": "ecdsa"
"size": 384

The choice of algorithm and key size are based on security needs.

Elliptic Curve (ECDSA) offers the following curves and security levels:

size	ASN1 OID	Signature Algorithm
256	prime256v1	ecdsa-with-SHA256
384	secp384r1	ecdsa-with-SHA384
521	secp521r1	ecdsa-with-SHA512

Likewise, these are the secure choices for RSA modulus:

size	Modulus (bits)	Signature Algorithm
2048	2048	sha256WithRSAEncryption
4096	4096	sha512WithRSAEncryption

TLS/SSL configuration - Client & fabric-ca Server

The steps below should be followed to set up a secure connection between client and server.

1. The fabric-ca server should be started with the following options set in the fabric-ca configuration file. The tls_cert and tls_key are used to set up the TLS protocol. The mutual_tls_ca requires that client certificates be signed by the specified CA and client is required to send its certificate. The configuration file for the server should contain the following:

...
"tls_cert":"tls_certificate.pem",
"tls_key":"tls_key.pem",
"mutual_tls_ca":"CA_root_cert.pem",
...

1. On client side, a configuration file (client-config.json) should be created as een below and placed in the client home directory. The ca_certfiles option is the set of root certificate authorities that clients uses when verifying server certificates. The client option contains one or more certificate chains to present to the other side of the connection.

{
"ca_certfiles":["CA_root_cert.pem"],
"client":[{"keyfile":"client-key.pem","certfile":"client.pem"}]
}

Once all the certificates and key have been properly configured on both client and server a secure connection should be established.

TLS configuration - Database & Server

Postgres

When specifying the connection string for the Postgres database in the server configuration file, we must indicate that we wish to use a secure connection. The connection string should be set as indicated below.

"driver":"postgres",
"data_source":"host=localhost port=5432 user=Username password=Password dbname=fabric-ca sslmode=verify-full",

sslmode - Enable SSL.

• verify-full - Always SSL (verify that the certification presented by the Postgres server was signed by a trusted CA and the Postgres server host name matches the one in the certificate).

We also need to set the TLS configuration in the fabric-ca server config file. If the database server requires client authentication that a client cert and key file needs to be provided. The following should be present in the fabric-ca server config:

"tls":{
  ...
  "db_client":{
    "ca_certfiles":["CA.pem"],
    "client":[{"keyfile":"client-key.pem","certfile":"client-cert.pem"}]
  }
},

ca_certfiles - The location of the root certificate file.

certfile - Client certificate file.

keyfile - Client key file.

MySQL

When specifying the connection string for the MySQL database in the server configuration file, we must indicate that we wish to use a secure connection. The connection string should be set with the tls=custom parameter as indicated below.

...
"driver":"mysql",
"data_source":"root:rootpw@tcp(localhost:3306)/fabric-ca?parseTime=true&tls=custom",
...

In the configuration file for the fabric-ca server, we need to define the elements below to establish a secure connection between fabric-ca server and MySQL server. If the database server requires client authentication that a client cert and key file needs to be provided.

"tls":{
  ...
  "db_client":{
    "ca_certfiles":["CA.pem"],
    "client":[{"keyfile":"client-key.pem","certfile":"client-cert.pem"}]
  }
},

ca_certfiles - The location of the root certificate file.

certfile - Client certificate file.

keyfile - Client key file.

Start the fabric-ca server

Execute the following commands to start the fabric-ca server. If you would like to specify debug-level logging, set the FABRIC_CA_DEBUG environment variable to true. And if you would like to run this in the background, append the "&" character to the command.

In server-config.json, specify the following properties. They specify the file to where the CA certificate and CA key are stored.

"ca_cert":"server-cert.pem",
"ca_key":"server-key.pem",

Run the following command to start fabric-ca server:

# fabric-ca server start -config ../testdata/server-config.json

It is now listening on localhost port 8888.

You can customize your fabric-ca config file at ../testdata/server-config.json. For example, if you want to disable authentication, you can do so by setting authentication to false. This prevents the fabric-ca server from looking at the authorization header. Auhentication is added by fabric-ca since CFSSL does not perform authentication. A standard HTTP basic authentication header is required for the enroll request. All other requests to the fabric-ca server will require a JWT-like token, but this work is not yet complete.

Enroll the admin client

See the FABRIC_CA/testdata/server-config.json file and note the "admin" user with a password of "adminpw". The following command gets an ecert for the admin user.

# fabric-ca client enroll admin adminpw http://localhost:8888

The enrollment certificate is stored at $FABRIC_CA_ENROLLMENT_DIR/cert.pem by default, but a different path can be specified by setting the FABRIC_CA_CERT_FILE environment variable to an absolute path name or a path relative to the current working directory.

The enrollment key is stored at $FABRIC_CA_ENROLLMENT_DIR/key.pem by default, but a different path can be specified by setting the FABRIC_CA_KEY_FILE environment variable to an absolute path name or a path relative to the current working directory.

The default value of the FABRIC_CA_ENROLLMENT_DIR environment variable is $FABRIC_CA_HOME.

The default value of the FABRIC_CA_HOME environment variable is $HOME/fabric-ca.

Reenroll

Suppose your enrollment certificate is about to expire. You can issue the reenroll command to renew your enrollment certificate as follows. Note that this is identical to the enroll command except no username or password is required. Instead, your previously stored private key is used to authenticate to the fabric-ca server.

# fabric-ca client reenroll http://localhost:8888

The enrollment certificate and enrollment key are stored in the same location as described in the previous section for the enroll command.

You can specify a new Certificate Signing Request JSON information when issue the reenroll command

# fabric-ca client reenroll http://localhost:8888 ../testdata/csr.json

Register a new user

The user performing the register request must be currently enrolled, and also this registrar must have the proper authority to register the type of user being registered. The registrar must have been enrolled with attribute "hf.Registrar.DelegateRoles". The DelegateRoles attribute specifies the types this registrar is allowed to register.

For example, the attributes for a registrar might look like this:

"attrs": [{"name":"hf.Registrar.DelegateRoles", "value":"client,user"}]

The registrar should then create a JSON file as defined below for the user being registered.

registerrequest.json:

{
  "id": "User1",
  "type": "client",
  "group": "bank_a",
  "attrs": [{"name":"AttributeName","value":"AttributeValue"}]
}

The following command will register the user.

# fabric-ca client register ../testdata/registerrequest.json http://localhost:8888

LDAP

The fabric-ca server can be configured to read from an LDAP server.

In particular, the fabric-ca server may connect to an LDAP server to do the following:

• authenticate a user prior to enrollment, and
• retrieve a user's attribute values which is used for authorization.

In order to configure the fabric-ca server to connect to an LDAP server, add a section of the following form to your fabric-ca server's configuration file:

{
   "ldap": {
       "url": "scheme://adminDN:pass@host[:port][/base]"
       "userfilter": "filter"
   }

where:

• scheme is one of ldap or ldaps;
• adminDN is the distinquished name of the admin user;
• pass is the password of the admin user;
• host is the hostname or IP address of the LDAP server;
• port is the optional port number, where default 389 for ldap and 636 for ldaps;
• base is the optional root of the LDAP tree to use for searches;
• filter is a filter to use when searching to convert a login user name to a distinquished name. For example, a value of (uid=%s) searches for LDAP entries with the value of a uid attribute whose value is the login user name. Similarly, (email=%s) may be used to login with an email address.

The following is a sample configuration section for the default settings for the OpenLDAP server whose docker image is at https://github.com/osixia/docker-openldap.

 "ldap": {
    "url": "ldap://cn=admin,dc=example,dc=org:admin@localhost:10389/dc=example,dc=org",
    "userfilter": "(uid=%s)"
 },

See FABRIC_CA/testdata/testconfig-ldap.json for the complete configuration file with this section. Also see FABRIC_CA/scripts/run-ldap-tests for a script which starts an OpenLDAP docker image, configures it, runs the LDAP tests in FABRIC_CA/cli/server/ldap/ldap_test.go, and stops the OpenLDAP server.

• A fabric-ca client or client SDK sends an enrollment request with a basic authorization header.
• The fabric-ca server receives the enrollment request, decodes the user/pass in the authorization header, looks up the DN (Distinquished Name) associated with the user using the "userfilter" from the configuration file, and then attempts an LDAP bind with the user's password. If successful, the enrollment processing is authorized and can proceed.

• A client SDK sends a request for a batch of tcerts with one or more attributes to the fabric-ca server.
• The fabric-ca server receives the tcert request and does as follows:
  • extracts the enrollment ID from the token in the authorization header (after validating the token);
  • does an LDAP search/query to the LDAP server, requesting all of the attribute names received in the tcert request;
  • the attribute values are placed in the tcert as normal

Setting up a cluster

Set up a proxy server. Haproxy is used in this example. Below is a basic configuration file that can be used to get haproxy up and running. Change hostname and port to reflect the settings of your fabric-ca servers.

haproxy.conf

global
      maxconn 4096
      daemon

defaults
      mode http
      maxconn 2000
      timeout connect 5000
      timeout client 50000
      timeout server 50000

listen http-in
      bind *:8888
      balance roundrobin
      server server1 <hostname:port>
      server server2 <hostname:port>
      server server3 <hostname:port>

Postgres

When starting the fabric-ca server, specify the database that you would like to connect to. In your fabric-ca configuration file, the following should be present for a Postgres database:

server-config.json

...
"driver":"postgres",
"data_source":"host=localhost port=5432 user=Username password=Password dbname=fabric-ca",
...

Change "host" and "dbname" to reflect where your database is located and the database you would like to connect to. Default port is used if none is specified. Enter username and password for a user that has permission to connect to the database.

Once your proxy, fabric-ca servers, and Postgres server are all running you can have your client direct traffic to the proxy server which will load balance and direct traffic to the appropriate fabric-ca server which will read/write from the Postgres database.

MySQL

When starting up the fabric-ca servers specify the database that you would like to connect to. In your fabric-ca configuration file, the following should be present for a Postgres database:

server-config.json

...
"driver":"mysql",
"data_source":"root:rootpw@tcp(localhost:3306)/fabric-ca?parseTime=true&tls=custom",
...

Change the host to reflect where your database is located. Change "root" and "rootpw" to the username and password you would like to use to connec to the database. The database is specified after the '/', specify the database you would like to connect to. Default port is used if none is specified.

Once your proxy, fabric-ca servers, and database servers are all running you can have your clients direct traffic to the proxy server which will load balance and direct traffic to the appropriate fabric-ca server which will read/write from the database.

Run the fabric-ca tests

To run the fabric-ca test, do the following.

WARNING: You must first stop the fabric-ca server which you started above; otherwise, it will fail with a port binding error.

# cd FABRIC_CA
# make unit-tests

Appendix

Postgres SSL Configuration

Basic instructions for configuring SSL on Postgres server:

1. In postgresql.conf, uncomment SSL and set to "on" (SSL=on)
2. Place Certificate and Key files Postgress data directory.

Instructions for generating self-signed certificates for: https://www.postgresql.org/docs/9.1/static/ssl-tcp.html

Note: Self-signed certificates are for testing purposes and should not be used in a production environment

Postgres Server - Require Client Certificates

1. Place certificates of the certificate authorities (CAs) you trust in the file root.crt in the Postgres data directory
2. In postgresql.conf, set "ssl_ca_file" to point to the root cert of client (CA cert)
3. Set the clientcert parameter to 1 on the appropriate hostssl line(s) in pg_hba.conf.

For more details on configuring SSL on the Postgres server, please refer to the following Postgres documentation: https://www.postgresql.org/docs/9.4/static/libpq-ssl.html

MySQL SSL Configuration

Basic instructions for configuring SSL on MySQL server:

1. Open or create my.cnf file for the server. Add or un-comment the lines below in [mysqld] section. These should point to the key and certificates for the server, and the root CA cert.

Instruction on creating server and client side certs: http://dev.mysql.com/doc/refman/5.7/en/creating-ssl-files-using-openssl.html

[mysqld] ssl-ca=ca-cert.pem ssl-cert=server-cert.pem ssl-key=server-key.pem

Can run the following query to confirm SSL has been enabled.

mysql> SHOW GLOBAL VARIABLES LIKE 'have_%ssl';

Should see:

+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| have_openssl  | YES   |
| have_ssl      | YES   |
+---------------+-------+

1. After the server-side SSL configuration is finished, the next step is to create a user who has a privilege to access the MySQL server over SSL. For that, log in to the MySQL server, and type:

mysql> GRANT ALL PRIVILEGES ON . TO 'ssluser'@'%' IDENTIFIED BY 'password' REQUIRE SSL; mysql> FLUSH PRIVILEGES;

If you want to give a specific ip address from which the user will access the server change the '%' to the specific ip address.

MySQL Server - Require Client Certificates Options for secure connections are similar to those used on the server side.

• ssl-ca identifies the Certificate Authority (CA) certificate. This option, if used, must specify the same certificate used by the server.
• ssl-cert identifies the client public key certificate.
• ssl-key identifies the client private key.

Suppose that you want to connect using an account that has no special encryption requirements or was created using a GRANT statement that includes the REQUIRE SSL option. As a recommended set of secure-connection options, start the MySQL server with at least --ssl-cert and --ssl-key, and invoke the fabric-ca server with ca_certfiles option set in the fabric-ca server file.

To require that a client certificate also be specified, create the account using the REQUIRE X509 option. Then the client must also specify the proper client key and certificate files or the MySQL server will reject the connection. CA cert, client cert, and client key are all required for the fabric-ca server.