FAB-1008: Chaincode library IF for invocation AC

This is work in progress on chaincode library interface
facilitating authentication of a client w.r.t. a list of
attributes the client claims to be in possession of.

Change-Id: I02dee9289175c94e951b7a15482485931821110b
Signed-off-by: Elli Androulaki <lli@zurich.ibm.com>

accesscontrol/api/authshim.go

@@ -0,0 +1,48 @@
+package authshim
+
+import "github.com/hyperledger/fabric/msp"
+
+/*
+Copyright IBM Corp. 2017 All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+		 http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// AttributeAuthShim is an interface based on top of the chaincode shim
+// to offer invocation access control based on identity attributes
+// TODO: Add NewAuthShimByTransientDataKey function
+// TODO: Make it later generic enough by providing as input the MSP identity
+type AttributeAuthShim interface {
+
+	// ReadAttributeValue would return the value of an attribute
+	ReadAttributeValue(attName string) ([]byte, error)
+
+	// Verify a proof of ownership of attribute atts using invocation
+	// data as the message to prove possession of attributes on
+	VerifyAttribute(atts []msp.Attribute)
+}
+
+// IdentityAuthShim is an interface based on top of the chaincode shim
+// to offer invocation access control based on identities
+// TODO: Add NewAuthShimByTransientDataKey
+// TODO: Add as setup parameter also ApplicationMSP
+type IdentityAuthShim interface {
+
+	// Verify a proof of ownership of an identity using the input
+	// message to prove possession of identity ownership on
+	VerifyIdentityOnMessage(identity msp.Identity, message string)
+
+	// Verify a proof of ownership of an identity using invocation
+	// data as the message to prove possession of attributes on
+	VerifyIdentity(identity msp.Identity)
+}