Copying shim/crypto to new a package

This change-set is the first step in the process of removing
shim/crypto and the dependencies from the ChaincodeStubInterface.

The change-set introduces a new top-level folder called
accesscontrol that has the same content of shim/crypto
plus a file containing some API.

Subsequent change-sets will remove shim/crypto and ensure
that the chaincode example can still work.

Change-Id: I8b1c701fd708e497dc6d95dbada5619979d05964
Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>

accesscontrol/api.go

@@ -0,0 +1,16 @@
+package accesscontrol
+
+// Attribute defines a name, value pair to be verified.
+type Attribute struct {
+	Name  string
+	Value []byte
+}
+
+// AttributesManager can be used to verify and read attributes.
+type AttributesManager interface {
+	ReadCertAttribute(attributeName string) ([]byte, error)
+
+	VerifyAttribute(attributeName string, attributeValue []byte) (bool, error)
+
+	VerifyAttributes(attrs ...*Attribute) (bool, error)
+}

accesscontrol/crypto/attr/attr_support.go

@@ -0,0 +1,209 @@
+/*
+Copyright IBM Corp. 2016 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.
+*/
+
+package attr
+
+import (
+	"bytes"
+	"crypto/x509"
+	"errors"
+
+	"github.com/hyperledger/fabric/accesscontrol"
+	"github.com/hyperledger/fabric/core/crypto/attributes"
+	"github.com/hyperledger/fabric/core/crypto/primitives"
+)
+
+// chaincodeHolder is the struct that hold the certificate and the metadata. An implementation is ChaincodeStub
+type chaincodeHolder interface {
+	// GetCallerCertificate returns caller certificate
+	GetCallerCertificate() ([]byte, error)
+
+	// GetCallerMetadata returns caller metadata
+	/*
+			TODO: ##attributes-keys-pending This code have be redefined to avoid use of metadata field.
+		GetCallerMetadata() ([]byte, error)
+	*/
+}
+
+//AttributesHandler is an entity can be used to both verify and read attributes.
+//		The functions declared can be used to access the attributes stored in the transaction certificates from the application layer. Can be used directly from the ChaincodeStub API but
+//		 if you need multiple access create a hanlder is better:
+// 	Multiple accesses
+// 		If multiple calls to the functions above are required, a best practice is to create an AttributesHandler instead of calling the functions multiple times, this practice will avoid creating a new AttributesHandler for each of these calls thus eliminating an unnecessary overhead.
+//    Example:
+//
+//		AttributesHandler, err := ac.NewAttributesHandlerImpl(stub)
+//		if err != nil {
+//			return false, err
+//		}
+//		AttributesHandler.VerifyAttribute(attributeName, attributeValue)
+//		... you can make other verifications and/or read attribute values by using the AttributesHandler
+type AttributesHandler interface {
+
+	//VerifyAttributes does the same as VerifyAttribute but it checks for a list of attributes and their respective values instead of a single attribute/value pair
+	// Example:
+	//    containsAttrs, error:= handler.VerifyAttributes(&ac.Attribute{"position",  "Software Engineer"}, &ac.Attribute{"company", "ACompany"})
+	VerifyAttributes(attrs ...*accesscontrol.Attribute) (bool, error)
+
+	//VerifyAttribute is used to verify if the transaction certificate has an attribute with name *attributeName* and value *attributeValue* which are the input parameters received by this function.
+	//Example:
+	//    containsAttr, error := handler.VerifyAttribute("position", "Software Engineer")
+	VerifyAttribute(attributeName string, attributeValue []byte) (bool, error)
+
+	//GetValue is used to read an specific attribute from the transaction certificate, *attributeName* is passed as input parameter to this function.
+	// Example:
+	//  attrValue,error:=handler.GetValue("position")
+	GetValue(attributeName string) ([]byte, error)
+}
+
+//AttributesHandlerImpl is an implementation of AttributesHandler interface.
+type AttributesHandlerImpl struct {
+	cert      *x509.Certificate
+	cache     map[string][]byte
+	keys      map[string][]byte
+	header    map[string]int
+	encrypted bool
+}
+
+type chaincodeHolderImpl struct {
+	Certificate []byte
+}
+
+// GetCallerCertificate returns caller certificate
+func (holderImpl *chaincodeHolderImpl) GetCallerCertificate() ([]byte, error) {
+	return holderImpl.Certificate, nil
+}
+
+//GetValueFrom returns the value of 'attributeName0' from a cert.
+func GetValueFrom(attributeName string, cert []byte) ([]byte, error) {
+	handler, err := NewAttributesHandlerImpl(&chaincodeHolderImpl{Certificate: cert})
+	if err != nil {
+		return nil, err
+	}
+	return handler.GetValue(attributeName)
+}
+
+//NewAttributesHandlerImpl creates a new AttributesHandlerImpl from a pb.ChaincodeSecurityContext object.
+func NewAttributesHandlerImpl(holder chaincodeHolder) (*AttributesHandlerImpl, error) {
+	// Getting certificate
+	certRaw, err := holder.GetCallerCertificate()
+	if err != nil {
+		return nil, err
+	}
+	if certRaw == nil {
+		return nil, errors.New("The certificate can't be nil.")
+	}
+	var tcert *x509.Certificate
+	tcert, err = primitives.DERToX509Certificate(certRaw)
+	if err != nil {
+		return nil, err
+	}
+
+	keys := make(map[string][]byte)
+
+	/*
+			TODO: ##attributes-keys-pending This code have be redefined to avoid use of metadata field.
+
+		//Getting Attributes Metadata from security context.
+		var attrsMetadata *attributespb.AttributesMetadata
+		var rawMetadata []byte
+		rawMetadata, err = holder.GetCallerMetadata()
+		if err != nil {
+			return nil, err
+		}
+
+		if rawMetadata != nil {
+			attrsMetadata, err = attributes.GetAttributesMetadata(rawMetadata)
+			if err == nil {
+				for _, entry := range attrsMetadata.Entries {
+					keys[entry.AttributeName] = entry.AttributeKey
+				}
+			}
+		}*/
+
+	cache := make(map[string][]byte)
+	return &AttributesHandlerImpl{tcert, cache, keys, nil, false}, nil
+}
+
+func (attributesHandler *AttributesHandlerImpl) readHeader() (map[string]int, bool, error) {
+	if attributesHandler.header != nil {
+		return attributesHandler.header, attributesHandler.encrypted, nil
+	}
+	header, encrypted, err := attributes.ReadAttributeHeader(attributesHandler.cert, attributesHandler.keys[attributes.HeaderAttributeName])
+	if err != nil {
+		return nil, false, err
+	}
+	attributesHandler.header = header
+	attributesHandler.encrypted = encrypted
+	return header, encrypted, nil
+}
+
+//GetValue is used to read an specific attribute from the transaction certificate, *attributeName* is passed as input parameter to this function.
+//	Example:
+//  	attrValue,error:=handler.GetValue("position")
+func (attributesHandler *AttributesHandlerImpl) GetValue(attributeName string) ([]byte, error) {
+	if attributesHandler.cache[attributeName] != nil {
+		return attributesHandler.cache[attributeName], nil
+	}
+	header, encrypted, err := attributesHandler.readHeader()
+	if err != nil {
+		return nil, err
+	}
+	value, err := attributes.ReadTCertAttributeByPosition(attributesHandler.cert, header[attributeName])
+	if err != nil {
+		return nil, errors.New("Error reading attribute value '" + err.Error() + "'")
+	}
+
+	if encrypted {
+		if attributesHandler.keys[attributeName] == nil {
+			return nil, errors.New("Cannot find decryption key for attribute")
+		}
+
+		value, err = attributes.DecryptAttributeValue(attributesHandler.keys[attributeName], value)
+		if err != nil {
+			return nil, errors.New("Error decrypting value '" + err.Error() + "'")
+		}
+	}
+	attributesHandler.cache[attributeName] = value
+	return value, nil
+}
+
+//VerifyAttribute is used to verify if the transaction certificate has an attribute with name *attributeName* and value *attributeValue* which are the input parameters received by this function.
+//	Example:
+//  	containsAttr, error := handler.VerifyAttribute("position", "Software Engineer")
+func (attributesHandler *AttributesHandlerImpl) VerifyAttribute(attributeName string, attributeValue []byte) (bool, error) {
+	valueHash, err := attributesHandler.GetValue(attributeName)
+	if err != nil {
+		return false, err
+	}
+	return bytes.Compare(valueHash, attributeValue) == 0, nil
+}
+
+//VerifyAttributes does the same as VerifyAttribute but it checks for a list of attributes and their respective values instead of a single attribute/value pair
+//	Example:
+//  	containsAttrs, error:= handler.VerifyAttributes(&ac.Attribute{"position",  "Software Engineer"}, &ac.Attribute{"company", "ACompany"})
+func (attributesHandler *AttributesHandlerImpl) VerifyAttributes(attrs ...*accesscontrol.Attribute) (bool, error) {
+	for _, attribute := range attrs {
+		val, err := attributesHandler.VerifyAttribute(attribute.Name, attribute.Value)
+		if err != nil {
+			return false, err
+		}
+		if !val {
+			return val, nil
+		}
+	}
+	return true, nil
+}