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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
| 2) issuance of Enrollment Certificates (ECerts);
| 3) issuance of Transaction Certificates (TCerts), providing both
anonymity and unlinkability when transacting on a Hyperledger Fabric
| 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
Getting Started
- Go 1.7+ installation or later
- **GOPATH** environment variable is set correctly
To install the fabric-ca command:
# go get
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
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
| - otherwise, if the ``HOME`` environment variable is set, use
| - 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
Initializing the 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 |
Starting the server
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``
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 <#fabric-ca-client>`__ section if
you do not want to configure the fabric-ca server to run in a cluster or
to use LDAP.
Server database configuration
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
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
"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
Setting up a cluster of fabric-ca servers
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
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
"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 ``$HOME/fabric-ca/server/server-cert.pem``. The file name must match
the name in the *client-config.json* file.
#### Enroll the bootstrap user
Unless the fabric-ca server is configured to use LDAP, it must be
configured with at least one pre-registered bootstrap user. In the
previous server-config.json in this document, that user has an
enrollment ID of *admin* with an enrollment secret of *adminpw*.
First, create a CSR (Certificate Signing Request) JSON file similar to
the following. Customize it as desired.
"key": { "algo": "ecdsa", "size": 256 },
"names": [
"O": "Hyperledger Fabric",
"OU": "Fabric CA",
"L": "Raleigh",
"ST": "North Carolina",
"C": "US"
See `CSR fields <#csr-fields>`__ for a description of the fields in this
file. When enrolling, the CN (Common Name) field is automatically set to
the enrollment ID which is *admin* in this example, so it can be omitted
from the csr.json file.
The following command enrolls the admin user and stores an enrollment
certificate (ECert) in the fabric-ca client's home directory.
# export FABRIC_CA_HOME=$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
``$FABRIC_CA_ENROLLMENT_DIR/cert.pem`` by default, but a different path
can be specified by setting the ``FABRIC_CA_CERT_FILE`` environment
The enrollment key is stored at ``$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.
Register a new identity
The user performing the register request must be currently enrolled, and
must also have the proper authority to register the type of user being
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
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.
Enrolling a peer identity
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 <#EnrollBootstrap>`__ 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.
Revoke a certificate or user
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"
Enabling TLS for a fabric-ca client
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:
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:
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:
[mysqld] ssl-ca=ca-cert.pem ssl-cert=server-cert.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 | +---------------+-------+``
2. 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
- 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.