BCCSP hash.Hash support

This change-set introduces support for hash.Hash at the BCCSP level.
The BCCSP will now return instances of hash.Hash to allow streaming hashing.
This change-set comes in the context of:
https://jira.hyperledger.org/browse/FAB-354

Change-Id: I78611c6ae90c58d7ac6c00d2c44eb8c3d5cf4d73
Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>

core/crypto/bccsp/bccsp.go

@@ -16,7 +16,10 @@ limitations under the License.
 
 package bccsp
 
-import "crypto"
+import (
+	"crypto"
+	"hash"
+)
 
 // Key represents a cryptographic key
 type Key interface {
@@ -114,8 +117,13 @@ type BCCSP interface {
 	GetKey(ski []byte) (k Key, err error)
 
 	// Hash hashes messages msg using options opts.
+	// If opts is nil, the default hash function will be used.
 	Hash(msg []byte, opts HashOpts) (hash []byte, err error)
 
+	// GetHash returns and instance of hash.Hash using options opts.
+	// If opts is nil, the default hash function will be returned.
+	GetHash(opts HashOpts) (h hash.Hash, err error)
+
 	// Sign signs digest using key k.
 	// The opts argument should be appropriate for the algorithm used.
 	//

core/crypto/bccsp/bccsp_opts.go

@@ -45,6 +45,9 @@ const (
 
 	// X509Certificate Label for X509 certificate realted operation
 	X509Certificate = "X509Certificate"
+
+	// DefaultHash is the identifier for the default hash function (see primitives package)
+	DefaultHash = "DEFAULT_HASH"
 )
 
 // ECDSAKeyGenOpts contains options for ECDSA key generation.

core/crypto/bccsp/sw/impl.go

@@ -26,6 +26,8 @@ import (
 
 	"crypto/rsa"
 
+	"hash"
+
 	"github.com/hyperledger/fabric/core/crypto/bccsp"
 	"github.com/hyperledger/fabric/core/crypto/primitives"
 	"github.com/hyperledger/fabric/core/crypto/utils"
@@ -463,17 +465,32 @@ func (csp *impl) GetKey(ski []byte) (k bccsp.Key, err error) {
 // Hash hashes messages msg using options opts.
 func (csp *impl) Hash(msg []byte, opts bccsp.HashOpts) (hash []byte, err error) {
 	if opts == nil {
-		return nil, errors.New("Invalid Opts parameter. It must not be nil.")
+		return primitives.Hash(msg), nil
 	}
 
 	switch opts.Algorithm() {
-	case bccsp.SHA:
+	case bccsp.DefaultHash, bccsp.SHA:
 		return primitives.Hash(msg), nil
 	default:
 		return nil, fmt.Errorf("Algorithm not recognized [%s]", opts.Algorithm())
 	}
 }
 
+// GetHash returns and instance of hash.Hash using options opts.
+// If opts is nil then the default hash function is returned.
+func (csp *impl) GetHash(opts bccsp.HashOpts) (h hash.Hash, err error) {
+	if opts == nil {
+		return primitives.NewHash(), nil
+	}
+
+	switch opts.Algorithm() {
+	case bccsp.SHA, bccsp.DefaultHash:
+		return primitives.NewHash(), nil
+	default:
+		return nil, fmt.Errorf("Algorithm not recognized [%s]", opts.Algorithm())
+	}
+}
+
 // Sign signs digest using key k.
 // The opts argument should be appropriate for the primitive used.
 //

core/crypto/bccsp/sw/impl_test.go

@@ -1245,3 +1245,49 @@ func TestKeyImportFromX509RSAPublicKey(t *testing.T) {
 		t.Fatal("Failed verifying RSA signature. Signature not valid.")
 	}
 }
+
+func TestGetHashAndHashCompatibility(t *testing.T) {
+	csp := getBCCSP(t)
+
+	msg1 := []byte("abcd")
+	msg2 := []byte("efgh")
+	msg := []byte("abcdefgh")
+
+	digest1, err := csp.Hash(msg, &bccsp.SHAOpts{})
+	if err != nil {
+		t.Fatalf("Failed computing HASH [%s]", err)
+	}
+
+	digest2, err := csp.Hash(msg, nil)
+	if err != nil {
+		t.Fatalf("Failed computing HASH [%s]", err)
+	}
+
+	if !bytes.Equal(digest1, digest2) {
+		t.Fatalf("Different hash computed. [%x][%x]", digest1, digest2)
+	}
+
+	h, err := csp.GetHash(nil)
+	if err != nil {
+		t.Fatalf("Failed getting hash.Hash instance [%s]", err)
+	}
+	h.Write(msg1)
+	h.Write(msg2)
+	digest3 := h.Sum(nil)
+
+	h2, err := csp.GetHash(&bccsp.SHAOpts{})
+	if err != nil {
+		t.Fatalf("Failed getting SHA hash.Hash instance [%s]", err)
+	}
+	h2.Write(msg1)
+	h2.Write(msg2)
+	digest4 := h2.Sum(nil)
+
+	if !bytes.Equal(digest3, digest4) {
+		t.Fatalf("Different hash computed. [%x][%x]", digest3, digest4)
+	}
+
+	if !bytes.Equal(digest1, digest3) {
+		t.Fatalf("Different hash computed. [%x][%x]", digest1, digest3)
+	}
+}