[FAB-12155] IssuerValidator Impl

This change-set does the following:
1. Implementes the IssuerValidator interface
in the following way: The Validate  method checks if
the passed credential correspond to that of a valid
member of a Fabric channel the validator is bound to.
The Fabric channel is representetd by an MSP manager that collects
all the MSPs registered in that channel.
2. It modify the manager.Manager to use the
implementation introduced in point 1.
3. Refactor the interfaces to avoid circual package dependecy
and local interfaces proliferation

Change-Id: I0b48b17f3e6246f34be3a1c28842352649fed917
Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>
Signed-off-by: Mathias Bjoerkqvist <mbj@zurich.ibm.com>

Author: adecaro

token/identity/identity.go

@@ -0,0 +1,38 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package identity
+
+import (
+	"github.com/hyperledger/fabric/msp"
+)
+
+// IssuingValidator is used to establish if the creator can issue tokens of the passed type.
+type IssuingValidator interface {
+	// Validate returns no error if the passed creator can issue tokens of the passed type,, an error otherwise.
+	Validate(creator PublicInfo, tokenType string) error
+}
+
+// PublicInfo is used to identify token owners.
+type PublicInfo interface {
+	Public() []byte
+}
+
+// DeserializerManager returns instances of Deserializer
+type DeserializerManager interface {
+	// Deserializer returns an instance of transaction.Deserializer for the passed channel
+	// if the channel exists
+	Deserializer(channel string) (Deserializer, error)
+}
+
+// Deserializer
+type Deserializer interface {
+	// Deserialize deserializes an identity.
+	// Deserialization will fail if the identity is associated to
+	// an msp that is different from this one that is performing
+	// the deserialization.
+	DeserializeIdentity(serializedIdentity []byte) (msp.Identity, error)
+}

token/identity/identity_test.go

@@ -0,0 +1,19 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package identity_test
+
+import "github.com/hyperledger/fabric/msp"
+
+//go:generate counterfeiter -o mock/issuing_validator.go -fake-name IssuingValidator . IssuingValidator
+//go:generate counterfeiter -o mock/public_info.go -fake-name PublicInfo . PublicInfo
+//go:generate counterfeiter -o mock/deserializer_manager.go -fake-name DeserializerManager . DeserializerManager
+//go:generate counterfeiter -o mock/deserializer.go -fake-name Deserializer . Deserializer
+//go:generate counterfeiter -o mock/identity.go -fake-name Identity ./../../msp/ Identity
+
+type Identity interface {
+	msp.Identity
+}