Using hex for txid computation

This change-set removes base64 encoding from the
computation of txid to use hex which guarantees
compatibility with the node-sdk.

Change-Id: I1c59390064d0432451dadf996f33d7bd106851f6
Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>

protos/utils/proputils.go

@@ -21,9 +21,10 @@ import (
 
 	"errors"
 
-	"encoding/base64"
 	"encoding/binary"
 
+	"encoding/hex"
+
 	"github.com/golang/protobuf/proto"
 	"github.com/hyperledger/fabric/bccsp"
 	"github.com/hyperledger/fabric/bccsp/factory"
@@ -533,7 +534,7 @@ func ComputeProposalTxID(nonce, creator []byte) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return base64.StdEncoding.EncodeToString(digest), nil
+	return hex.EncodeToString(digest), nil
 }
 
 func CheckProposalTxID(txid string, nonce, creator []byte) error {

protos/utils/proputils_test.go

@@ -25,6 +25,9 @@ import (
 	"fmt"
 	"os"
 
+	"crypto/sha256"
+	"encoding/hex"
+
 	"github.com/hyperledger/fabric/common/util"
 	"github.com/hyperledger/fabric/msp"
 	mspmgmt "github.com/hyperledger/fabric/msp/mgmt"
@@ -338,6 +341,40 @@ func TestEnvelope(t *testing.T) {
 	}
 }
 
+func TestProposalTxID(t *testing.T) {
+	nonce := []byte{1}
+	creator := []byte{2}
+
+	txid, err := ComputeProposalTxID(nonce, creator)
+	assert.NotEmpty(t, txid, "TxID cannot be empty.")
+	assert.NoError(t, err, "Failed computing txID")
+	assert.Nil(t, CheckProposalTxID(txid, nonce, creator))
+	assert.Error(t, CheckProposalTxID("", nonce, creator))
+
+	txid, err = ComputeProposalTxID(nil, nil)
+	assert.NotEmpty(t, txid, "TxID cannot be empty.")
+	assert.NoError(t, err, "Failed computing txID")
+}
+
+func TestComputeProposalTxID(t *testing.T) {
+	txid, err := ComputeProposalTxID([]byte{1}, []byte{1})
+	assert.NoError(t, err, "Failed computing TxID")
+
+	// Compute the function computed by ComputeProposalTxID,
+	// namely, base64(sha256(nonce||creator))
+	hf := sha256.New()
+	hf.Write([]byte{1})
+	hf.Write([]byte{1})
+	hashOut := hf.Sum(nil)
+	txid2 := hex.EncodeToString(hashOut)
+
+	t.Logf("% x\n", hashOut)
+	t.Logf("% s\n", txid)
+	t.Logf("% s\n", txid2)
+
+	assert.Equal(t, txid, txid2)
+}
+
 var signer msp.SigningIdentity
 var signerSerialized []byte