README ¶
Client Identity Chaincode Library
The client identity chaincode library enables you to write chaincode which makes access control decisions based on the identity of the client (i.e. the invoker of the chaincode). In particular, you may make access control decisions based on either or both of the following associated with the client:
- the client identity's MSP (Membership Service Provider) ID
- an attribute associated with the client identity
Attributes are simply name and value pairs associated with an identity.
For example, email=me@gmail.com
indicates an identity has the email
attribute with a value of me@gmail.com
.
Using the client identity chaincode library
This section describes how to use the client identity chaincode library.
All code samples below assume two things:
- The type of the
stub
variable isChaincodeStubInterface
as passed to your chaincode. - You have added the following import statement to your chaincode.
import "github.com/hyperledger/fabric/core/chaincode/lib/cid"
Getting the client's ID
The following demonstrates how to get an ID for the client which is guaranteed to be unique within the MSP:
id, err := cid.GetID(stub)
Getting the MSP ID
The following demonstrates how to get the MSP ID of the client's identity:
mspid, err := cid.GetMSPID(stub)
Getting an attribute value
The following demonstrates how to get the value of the attr1 attribute:
val, ok, err := cid.GetAttributeValue(stub, "attr1")
if err != nil {
// There was an error trying to retrieve the attribute
}
if !ok {
// The client identity does not possess the attribute
}
// Do something with the value of 'val'
Asserting an attribute value
Often all you want to do is to make an access control decision based on the value
of an attribute, i.e. to assert the value of an attribute. For example, the following
will return an error if the client does not have the myapp.admin
attribute
with a value of true
:
err := cid.AssertAttributeValue(stub, "myapp.admin", "true")
if err != nil {
// Return an error
}
This is effectively using attributes to implement role-based access control, or RBAC for short.
Getting the client's X509 certificate
The following demonstrates how to get the X509 certificate of the client, or nil if the client's identity was not based on an X509 certificate:
cert, err := cid.GetX509Certificate(stub)
Note that both cert
and err
may be nil as will be the case if the identity
is not using an X509 certificate.
Performing multiple operations more efficiently
Sometimes you may need to perform multiple operations in order to make an access decision. For example, the following demonstrates how to grant access to identities with MSP org1MSP and attr1 OR with MSP org1MSP and attr2.
// Get the client ID object
id, err := cid.New(stub)
if err != nil {
// Handle error
}
mspid, err := id.GetMSPID()
if err != nil {
// Handle error
}
switch mspid {
case "org1MSP":
err = id.AssertAttributeValue("attr1", "true")
case "org2MSP":
err = id.AssertAttributeValue("attr2", "true")
default:
err = errors.New("Wrong MSP")
}
Although it is not required, it is more efficient to make the cid.New
call
to get the ClientIdentity object if you need to perform multiple operations,
as demonstrated above.
Adding Attributes to Identities
This section describes how to add custom attributes to certificates when using Hyperledger Fabric CA as well as when using an external CA.
Managing attributes with Fabric CA
There are two methods of adding attributes to an enrollment certificate with fabric-ca:
-
When you register an identity, you can specify that an enrollment certificate issued for the identity should by default contain an attribute. This behavior can be overridden at enrollment time, but this is useful for establishing default behavior and, assuming registration occurs outside of your application, does not require any application change.
The following shows how to register user1 with two attributes: app1Admin and email. The ":ecert" suffix causes the appAdmin attribute to be inserted into user1's enrollment certificate by default. The email attribute is not added to the enrollment certificate by default.
fabric-ca-client register --id.name user1 --id.secret user1pw --id.type user --id.affiliation org1 --id.attrs 'app1Admin=true:ecert,email=user1@gmail.com'
-
When you enroll an identity, you may request that one or more attributes be added to the certificate. For each attribute requested, you may specify whether the attribute is optional or not. If it is not optional but does not exist for the identity, enrollment fails.
The following shows how to enroll user1 with the email attribute, without the app1Admin attribute and optionally with the phone attribute (if the user possesses phone attribute).
fabric-ca-client enroll -u http://user1:user1pw@localhost:7054 --enrollment.attrs "email,phone:opt"
Attribute format in a certificate
Attributes are stored inside an X509 certificate as an extension with an
ASN.1 OID (Abstract Syntax Notation Object IDentifier)
of 1.2.3.4.5.6.7.8.1
. The value of the extension is a JSON string of the
form {"attrs":{<attrName>:<attrValue}}
. The following is a sample of a
certificate which contains the attr1
attribute with a value of val1
.
See the final entry in the X509v3 extensions section. Note also that the JSON
entry could contain multiple attributes, though this sample shows only one.
Certificate:
Data:
Version: 3 (0x2)
Serial Number:
1e:49:98:e9:f4:4f:d0:03:53:bf:36:81:c0:a0:a4:31:96:4f:52:75
Signature Algorithm: ecdsa-with-SHA256
Issuer: CN=fabric-ca-server
Validity
Not Before: Sep 8 03:42:00 2017 GMT
Not After : Sep 8 03:42:00 2018 GMT
Subject: CN=MyTestUserWithAttrs
Subject Public Key Info:
Public Key Algorithm: id-ecPublicKey
EC Public Key:
pub:
04:e6:07:5a:f7:09:d5:af:38:e3:f7:a2:90:77:0e:
32:67:5b:70:a7:37:ca:b5:c9:d8:91:77:39:ae:03:
a0:36:ad:72:b3:3c:89:6d:1e:f6:1b:6d:2a:88:49:
92:6e:6e:cc:bc:81:52:fa:19:88:18:5c:d7:6e:eb:
d4:73:cc:51:79
ASN1 OID: prime256v1
X509v3 extensions:
X509v3 Key Usage: critical
Certificate Sign
X509v3 Basic Constraints: critical
CA:FALSE
X509v3 Subject Key Identifier:
D8:28:B4:C0:BC:92:4A:D3:C3:8C:54:6C:08:86:33:10:A6:8D:83:AE
X509v3 Authority Key Identifier:
keyid:C4:B3:FE:76:0D:E2:DE:3C:FC:75:FB:AE:55:86:04:F0:BB:7F:F6:01
X509v3 Subject Alternative Name:
DNS:Anils-MacBook-Pro.local
1.2.3.4.5.6.7.8.1:
{"attrs":{"attr1":"val1"}}
Signature Algorithm: ecdsa-with-SHA256
30:45:02:21:00:fb:84:a9:65:29:b2:f4:d3:bc:1a:8b:47:92:
5e:41:27:2d:26:ec:f7:cd:aa:86:46:a4:ac:da:25:be:40:1d:
c5:02:20:08:3f:49:86:58:a7:20:48:64:4c:30:1b:da:a9:a2:
f2:b4:16:28:f6:fd:e1:46:dd:6b:f2:3f:2f:37:4a:4c:72
If you want to use the client identity library to extract or assert attribute
values as described previously but you are not using Hyperledger Fabric CA,
then you must ensure that the certificates which are issued by your external CA
contain attributes of the form shown above. In particular, the certificates
must contain the 1.2.3.4.5.6.7.8.1
X509v3 extension with a JSON value
containing the attribute names and values for the identity.
Documentation ¶
Index ¶
- func AssertAttributeValue(stub ChaincodeStubInterface, attrName, attrValue string) error
- func GetAttributeValue(stub ChaincodeStubInterface, attrName string) (value string, found bool, err error)
- func GetID(stub ChaincodeStubInterface) (string, error)
- func GetMSPID(stub ChaincodeStubInterface) (string, error)
- func GetX509Certificate(stub ChaincodeStubInterface) (*x509.Certificate, error)
- type ChaincodeStubInterface
- type ClientIdentity
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func AssertAttributeValue ¶
func AssertAttributeValue(stub ChaincodeStubInterface, attrName, attrValue string) error
AssertAttributeValue checks to see if an attribute value equals the specified value
func GetAttributeValue ¶
func GetAttributeValue(stub ChaincodeStubInterface, attrName string) (value string, found bool, err error)
GetAttributeValue returns value of the specified attribute
func GetID ¶
func GetID(stub ChaincodeStubInterface) (string, error)
GetID returns the ID associated with the invoking identity. This ID is guaranteed to be unique within the MSP.
func GetMSPID ¶
func GetMSPID(stub ChaincodeStubInterface) (string, error)
GetMSPID returns the ID of the MSP associated with the identity that submitted the transaction
func GetX509Certificate ¶
func GetX509Certificate(stub ChaincodeStubInterface) (*x509.Certificate, error)
GetX509Certificate returns the X509 certificate associated with the client, or nil if it was not identified by an X509 certificate.
Types ¶
type ChaincodeStubInterface ¶
type ChaincodeStubInterface interface { // 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) }
ChaincodeStubInterface is used by deployable chaincode apps to get identity of the agent (or user) submitting the transaction.
type ClientIdentity ¶
type ClientIdentity interface { // GetID returns the ID associated with the invoking identity. This ID // is guaranteed to be unique within the MSP. GetID() (string, error) // Return the MSP ID of the client GetMSPID() (string, error) // GetAttributeValue returns the value of the client's attribute named `attrName`. // If the client possesses the attribute, `found` is true and `value` equals the // value of the attribute. // If the client does not possess the attribute, `found` is false and `value` // equals "". GetAttributeValue(attrName string) (value string, found bool, err error) // AssertAttributeValue verifies that the client has the attribute named `attrName` // with a value of `attrValue`; otherwise, an error is returned. AssertAttributeValue(attrName, attrValue string) error // GetX509Certificate returns the X509 certificate associated with the client, // or nil if it was not identified by an X509 certificate. GetX509Certificate() (*x509.Certificate, error) }
ClientIdentity represents information about the identity that submitted the transaction
func New ¶
func New(stub ChaincodeStubInterface) (ClientIdentity, error)
New returns an instance of ClientIdentity