Fabric CA User’s Guide

Fabric CA is a Certificate Authority for Hyperledger Fabric.

It provides features such as:
1) registration of identities, or connects to LDAP as the user registry;
2) issuance of Enrollment Certificates (ECerts);
3) issuance of Transaction Certificates (TCerts), providing both anonymity and unlinkability when transacting on a Hyperledger Fabric blockchain;
4) certificate renewal and revocation.

Fabric CA consists of both a server and a client component as described later in this document.

For developers interested in contributing to Fabric CA, see the Fabric CA repository for more information.

Getting Started


  • Go 1.7+ installation or later
  • GOPATH environment variable is set correctly


To install the fabric-ca command:

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

The Fabric CA CLI

The following shows the fabric-ca CLI usage:

# 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 server and fabric-ca client commands are discussed below.

If you would like to enable debug-level logging (for server or client), set the FABRIC_CA_DEBUG environment variable to true.

Since fabric-ca is built on top of CFSSL, the fabric-ca cfssl commands are available but are not discussed in this document. See CFSSL for more information.

Fabric CA Server

This section describes the fabric-ca server.

You must initialize the Fabric CA server before starting it.

The fabric-ca server’s home directory is determined as follows:
- if the FABRIC_CA_HOME environment variable is set, use its value;
- otherwise, if the HOME environment variable is set, use $HOME/fabric-ca;
- otherwise, use `/var/hyperledger/fabric/dev/fabric-ca’.

For the remainder of this server section, we assume that you have set the FABRIC_CA_HOME environment variable to $HOME/fabric-ca/server.

Initialize the Fabric CA server as follows:

# fabric-ca server init CSR-JSON-FILE

The following is a sample CSR-JSON-FILE which you can customize as desired. The “CSR” stands for “Certificate Signing Request”.

If you are going to connect to the fabric-ca server remotely over TLS, replace “localhost” in the CSR-JSON-FILE below with the hostname where you will be running your fabric-ca server.

  "CN": "localhost",
  "key": { "algo": "ecdsa", "size": 256 },
  "names": [
        "O": "Hyperledger Fabric",
        "OU": "Fabric CA",
        "L": "Raleigh",
        "ST": "North Carolina",
        "C": "US"

All of the fields above pertain to the X.509 certificate which is generated by the fabric server init command as follows:

###### CSR fields
  • CN is the Common Name
  • keys specifies the algorithm and key size as described below
  • O is the organization name
  • OU is the organization unit
  • L is the location or city
  • ST is the state
  • C is the country

The fabric-ca server init command generates a self-signed X.509 certificate. It stores the certificate in the server-cert.pem file and the key in the server-key.pem file in the Fabric CA server’s home directory.

Algorithms and key sizes

The CSR-JSON-FILE can be customized to generate X.509 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 prime256v1 and signature algorithm ecdsa-with-SHA256:

"key": {
   "algo": "ecdsa"
   "size": 256

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

Elliptic Curve (ECDSA) offers the following key size options:

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

RSA offers the following key size options:

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

Create a file named server-config.json as shown below in your fabric-ca server’s home directory (e.g. $HOME/fabric-ca/server).

 "tls_disable": false,
 "ca_cert": "server-cert.pem",
 "ca_key": "server-key.pem",
 "user_registry": { "max_enrollments": 0 },
 "tls": {
     "tls_cert": "server-cert.pem",
     "tls_key": "server-key.pem"
 "users": {
    "admin": {
      "pass": "adminpw",
      "type": "client",
      "group": "bank_a",
      "attrs": [
         {"name":"hf.Registrar.DelegateRoles", "value": "client"}
 "groups": {
   "banks_and_institutions": {
     "banks": ["bank_a", "bank_b", "bank_c"],
     "institutions": ["institution_a"]
 "signing": {
    "default": {
       "usages": ["cert sign"],
       "expiry": "8000h",
       "ca_constraint": {"is_ca": true}

Now you may start the Fabric CA server as follows:

# fabric-ca server start -address '' -config server-config.json

To cause the fabric-ca server to listen on http rather than https, set tls_disable to true in the server-config.json file.

To limit the number of times that the same secret (or password) can be used for enrollment, set the max_enrollments in the server-config.json file to the appropriate value. If you set the value to 1, the fabric-ca server allows passwords to only be used once for a particular enrollment ID. If you set the value to 0, the fabric-ca server places no limit on the number of times that a secret can be reused for enrollment. The default value is 0.

The fabric-ca server should now be listening on port 7054.

You may skip to the Fabric CA Client section if you do not want to configure the fabric-ca server to run in a cluster or to use LDAP.

This section describes how to configure the fabric-ca server to connect to Postgres or MySQL databases. The default database is SQLite and the default database file is fabric-ca.db in the Fabric CA’s home directory.

If you don’t care about running the fabric-ca server in a cluster, you may skip this section; otherwise, you must configure either Postgres or MySQL as described below.


The following sample may be added to the server-config.json file in order to connect to a Postgres database. Be sure to customize the various values appropriately.

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

Specifying sslmode enables SSL, and a value of verify-full means to verify that the certificate presented by the postgres server was signed by a trusted CA and that the postgres server’s 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, then a client cert and key file needs to be provided. The following should be present in the fabric-ca server config:


ca_certfiles - The names of the trusted root certificate files.

certfile - Client certificate file.

keyfile - Client key file.


The following sample may be added to the server-config.json file in order to connect to a MySQL database. Be sure to customize the various values appropriately.


If connecting over TLS to the MySQL server, the tls.db_client section is also required as described in the Postgres section above.

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 are 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.

When LDAP is configured, enrollment works as follows:

  • 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.

When LDAP is configured, attribute retrieval works as follows:

  • 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

You may use any IP sprayer to load balance to a cluster of fabric-ca servers. This section provides an example of how to set up Haproxy to route to a fabric-ca server cluster. Be sure to change hostname and port to reflect the settings of your fabric-ca servers.


         maxconn 4096

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

   listen http-in
         bind *:7054
         balance roundrobin
         server server1 hostname1:port
         server server2 hostname2:port
         server server3 hostname3:port

## Fabric CA Client

This section describes how to use the fabric-ca client.

The default fabric-ca client’s home directory is $HOME/fabric-ca, but this can be changed by setting the FABRIC_CA_HOME environment variable.

You must create a file named client-config.json in the fabric-ca client’s home directory. The following is a sample client-config.json file:

  "signing": {
    "default": {
       "usages": ["cert sign"],
       "expiry": "8000h"

You must also copy the server’s certificate into the client’s home directory. In the examples in this document, the server’s certificate is at $HOME/fabric-ca/server/server-cert.pem. The file name must match the name in the client-config.json file.

#### Enroll the bootstrap user

Unless the fabric-ca server is configured to use LDAP, it must be configured with at least one pre-registered bootstrap user. In the previous server-config.json in this document, that user has an enrollment ID of admin with an enrollment secret of adminpw.

First, create a CSR (Certificate Signing Request) JSON file similar to

the following. Customize it as desired.

  "key": { "algo": "ecdsa", "size": 256 },
  "names": [
        "O": "Hyperledger Fabric",
        "OU": "Fabric CA",
        "L": "Raleigh",
        "ST": "North Carolina",
        "C": "US"

See CSR fields for a description of the fields in this file. When enrolling, the CN (Common Name) field is automatically set to the enrollment ID which is admin in this example, so it can be omitted from the csr.json file.

The following command enrolls the admin user and stores an enrollment certificate (ECert) in the fabric-ca client’s home directory.

# export FABRIC_CA_HOME=$HOME/fabric-ca/clients/admin
# fabric-ca client enroll -config client-config.json admin adminpw http://localhost:7054 csr.json

You should see a message similar to [INFO] enrollment information was successfully stored in which indicates where the certificate and key files were stored.

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.

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.

If FABRIC_CA_ENROLLMENT_DIR is not set, the value of the FABRIC_CA_HOME environment variable is used in its place.

The user performing the register request must be currently enrolled, and must also have the proper authority to register the type of user being registered.

In particular, the invoker’s identity must have been registered with the attribute “hf.Registrar.Roles”. This attribute specifies the types of identities that the registrar is allowed to register.

For example, the attributes for a registrar might be as follows, indicating that this registrar identity can register peer, application, and user identities.

"attrs": [{"name":"hf.Registrar.Roles", "value":"peer,app,user"}]

To register a new identity, you must first create a JSON file similar to the one below which defines information for the identity being registered. This is a sample of registration information for a peer.

  "id": "peer1",
  "type": "peer",
  "group": "bank_a",
  "attrs": [{"name":"SomeAttrName","value":"SomeAttrValue"}]

The id field is the enrollment ID of the identity.

The type field is the type of the identity: orderer, peer, app, or user.

The group field must be a valid group name as found in the server-config.json file.

The attrs field is optional and is not required for a peer, but is shown here as example of how you associate attributes with any identity.

Assuming you store the information above in a file named register.json, the following command uses the admin user’s credentials to register the peer1 identity.

# export FABRIC_CA_HOME=$HOME/fabric-ca/clients/admin
# fabric-ca client register -config client-config.json register.json http://localhost:7054

The output of a successful fabric-ca client register command is a password similar to One time password: gHIexUckKpHz. Make a note of your password to use in the following section to enroll a peer.

Now that you have successfully registered a peer identity, you may now enroll the peer given the enrollment ID and secret (i.e. the password from the previous section).

First, create a CSR (Certificate Signing Request) JSON file similar to the one described in the Enrolling the bootstrap user section. Name the file csr.json for the following example.

This is similar to enrolling the bootstrap user except that we also demonstrate how to use environment variables to place the key and certificate files in a specific location. The following example shows how to place them into a Hyperledger Fabric MSP (Membership Service Provider) directory structure. The MSP_DIR environment variable refers to the root directory of MSP in Hyperledger Fabric and the $MSP_DIR/signcerts and $MSP_DIR/keystore directories must exist.

Also note that you must replace <secret> with the secret which was returned from the registration in the previous section.

# export FABRIC_CA_CERT_FILE=$MSP_DIR/signcerts/peer.pem
# export FABRIC_CA_KEY_FILE=$MSP_DIR/keystore/key.pem
# fabric-ca client enroll -config client-config.json peer1 <secret> https://localhost:7054 csr.json

The peer.pem and key.pem files should now exist at the locations specified by the environment variables.

In order to revoke a certificate or user, the calling identity must have the hf.Revoker attribute.

You may revoke a specific certificate by specifying its AKI (Authority Key Identifier) and its serial number, as shown below.

fabric-ca client revoke -config client-config.json -aki xxx -serial yyy -reason "you're bad" https://localhost:7054

The following command disables a user’s identity and also revokes all of the certificates associated with the identity. All future requests received by the fabric-ca server from this identity will be rejected.

fabric-ca client revoke -config client-config.json https://localhost:7054 ENROLLMENT-ID -reason "you're really bad"

This section describes in more detail how to configure TLS for a fabric-ca client.

The following sections may be configured in the client-config.json.


The ca_certfiles option is the set of root certificates trusted by the client. This will typically just be the root fabric-ca server’s certificate found in the server’s home directory in the server-cert.pem file.

The client option is required only if mutual TLS is configured on the server.


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:


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.