updated (co)signed tree head structuresv0.2.0

- Added key_hash in tree head, see motivation in api.md
- Added separate types for (co)signed tree heads
- Refactored tree head HTTP APIs to be current, see api.md

5 files changed, 50 insertions, 98 deletions

diff --git a/pkg/types/ascii.go b/pkg/types/ascii.go
index f0a96ad..72abfcb 100644
--- a/pkg/types/ascii.go
+++ b/pkg/types/ascii.go
@@ -18,7 +18,7 @@ const (
 
 	// NumField* is the number of unique keys in an incoming ASCII message
 	NumFieldLeaf                    = 4
-	NumFieldSignedTreeHead          = 5
+	NumFieldSignedTreeHead          = 4
 	NumFieldConsistencyProof        = 3
 	NumFieldInclusionProof          = 3
 	NumFieldLeavesRequest           = 2
@@ -28,11 +28,11 @@ const (
 	NumFieldCosignatureRequest      = 2
 
 	// New leaf keys
-	ShardHint            = "shard_hint"
-	Checksum             = "checksum"
-	Signature            = "signature"
-	VerificationKey      = "verification_key"
-	DomainHint           = "domain_hint"
+	ShardHint       = "shard_hint"
+	Checksum        = "checksum"
+	Signature       = "signature"
+	VerificationKey = "verification_key"
+	DomainHint      = "domain_hint"
 
 	// Inclusion proof keys
 	LeafHash      = "leaf_hash"
@@ -53,8 +53,9 @@ const (
 	TreeSize  = "tree_size"
 	RootHash  = "root_hash"
 
-	// Signature and signer-identity keys
-	KeyHash   = "key_hash"
+	// Witness signature-identity keys
+	KeyHash     = "key_hash"
+	Cosignature = "cosignature"
 )
 
 // MessageASCI is a wrapper that manages ASCII key-value pairs
@@ -219,19 +220,29 @@ func (sth *SignedTreeHead) MarshalASCII(w io.Writer) error {
 	if err := writeASCII(w, RootHash, hex.EncodeToString(sth.RootHash[:])); err != nil {
 		return fmt.Errorf("writeASCII: %v", err)
 	}
-	for _, sigident := range sth.SigIdent {
-		if err := sigident.MarshalASCII(w); err != nil {
-			return fmt.Errorf("MarshalASCII: %v", err)
+	if err := writeASCII(w, Signature, hex.EncodeToString(sth.Signature[:])); err != nil {
+		return fmt.Errorf("writeASCII: %v", err)
+	}
+	return nil
+}
+
+func (cth *CosignedTreeHead) MarshalASCII(w io.Writer) error {
+	if err := cth.SignedTreeHead.MarshalASCII(w); err != nil {
+		return fmt.Errorf("writeASCII: %v", err)
+	}
+	for _, si := range cth.SigIdent {
+		if err := si.MarshalASCII(w); err != nil {
+			return fmt.Errorf("writeASCII: %v", err)
 		}
 	}
 	return nil
 }
 
 func (si *SigIdent) MarshalASCII(w io.Writer) error {
-	if err := writeASCII(w, Signature, hex.EncodeToString(si.Signature[:])); err != nil {
+	if err := writeASCII(w, KeyHash, hex.EncodeToString(si.KeyHash[:])); err != nil {
 		return fmt.Errorf("writeASCII: %v", err)
 	}
-	if err := writeASCII(w, KeyHash, hex.EncodeToString(si.KeyHash[:])); err != nil {
+	if err := writeASCII(w, Cosignature, hex.EncodeToString(si.Signature[:])); err != nil {
 		return fmt.Errorf("writeASCII: %v", err)
 	}
 	return nil
@@ -280,7 +291,6 @@ func (sth *SignedTreeHead) UnmarshalASCII(r io.Reader) error {
 		return fmt.Errorf("NewMessageASCII: %v", err)
 	}
 
-	// TreeHead
 	if sth.Timestamp, err = msg.GetUint64(Timestamp); err != nil {
 		return fmt.Errorf("GetUint64(Timestamp): %v", err)
 	}
@@ -290,30 +300,8 @@ func (sth *SignedTreeHead) UnmarshalASCII(r io.Reader) error {
 	if sth.RootHash, err = msg.GetHash(RootHash); err != nil {
 		return fmt.Errorf("GetHash(RootHash): %v", err)
 	}
-
-	// SigIdent
-	signatures := msg.GetStrings(Signature)
-	if len(signatures) == 0 {
-		return fmt.Errorf("no signer")
-	}
-	keyHashes := msg.GetStrings(KeyHash)
-	if len(signatures) != len(keyHashes) {
-		return fmt.Errorf("mismatched signature-signer count")
-	}
-	sth.SigIdent = make([]*SigIdent, 0, len(signatures))
-	for i, n := 0, len(signatures); i < n; i++ {
-		var signature [SignatureSize]byte
-		if err := decodeHex(signatures[i], signature[:]); err != nil {
-			return fmt.Errorf("decodeHex: %v", err)
-		}
-		var hash [HashSize]byte
-		if err := decodeHex(keyHashes[i], hash[:]); err != nil {
-			return fmt.Errorf("decodeHex: %v", err)
-		}
-		sth.SigIdent = append(sth.SigIdent, &SigIdent{
-			Signature: &signature,
-			KeyHash:   &hash,
-		})
+	if sth.Signature, err = msg.GetSignature(Signature); err != nil {
+		return fmt.Errorf("GetHash(RootHash): %v", err)
 	}
 	return nil
 }
@@ -401,7 +389,7 @@ func (req *CosignatureRequest) UnmarshalASCII(r io.Reader) error {
 		return fmt.Errorf("NewMessageASCII: %v", err)
 	}
 
-	if req.Signature, err = msg.GetSignature(Signature); err != nil {
+	if req.Signature, err = msg.GetSignature(Cosignature); err != nil {
 		return fmt.Errorf("GetSignature: %v", err)
 	}
 	if req.KeyHash, err = msg.GetHash(KeyHash); err != nil {
diff --git a/pkg/types/ascii_test.go b/pkg/types/ascii_test.go
index c3f9e98..fc3f486 100644
--- a/pkg/types/ascii_test.go
+++ b/pkg/types/ascii_test.go
@@ -134,26 +134,14 @@ func TestSignedTreeHeadMarshalASCII(t *testing.T) {
 			TreeSize:  456,
 			RootHash:  testBuffer32,
 		},
-		SigIdent: []*SigIdent{
-			&SigIdent{
-				Signature: testBuffer64,
-				KeyHash:   testBuffer32,
-			},
-			&SigIdent{
-				Signature: testBuffer64,
-				KeyHash:   testBuffer32,
-			},
-		},
+		Signature: testBuffer64,
 	}
 	wantBuf := bytes.NewBufferString(fmt.Sprintf(
-		"%s%s%d%s"+"%s%s%d%s"+"%s%s%x%s"+"%s%s%x%s"+"%s%s%x%s"+"%s%s%x%s"+"%s%s%x%s",
+		"%s%s%d%s"+"%s%s%d%s"+"%s%s%x%s"+"%s%s%x%s",
 		Timestamp, Delim, 123, EOL,
 		TreeSize, Delim, 456, EOL,
 		RootHash, Delim, testBuffer32[:], EOL,
 		Signature, Delim, testBuffer64[:], EOL,
-		KeyHash, Delim, testBuffer32[:], EOL,
-		Signature, Delim, testBuffer64[:], EOL,
-		KeyHash, Delim, testBuffer32[:], EOL,
 	))
 	buf := bytes.NewBuffer(nil)
 	if err := sth.MarshalASCII(buf); err != nil {
@@ -236,14 +224,11 @@ func TestSignedTreeHeadUnmarshalASCII(t *testing.T) {
 		{
 			description: "valid",
 			buf: bytes.NewBufferString(fmt.Sprintf(
-				"%s%s%d%s"+"%s%s%d%s"+"%s%s%x%s"+"%s%s%x%s"+"%s%s%x%s"+"%s%s%x%s"+"%s%s%x%s",
+				"%s%s%d%s"+"%s%s%d%s"+"%s%s%x%s"+"%s%s%x%s",
 				Timestamp, Delim, 123, EOL,
 				TreeSize, Delim, 456, EOL,
 				RootHash, Delim, testBuffer32[:], EOL,
 				Signature, Delim, testBuffer64[:], EOL,
-				KeyHash, Delim, testBuffer32[:], EOL,
-				Signature, Delim, testBuffer64[:], EOL,
-				KeyHash, Delim, testBuffer32[:], EOL,
 			)),
 			wantSth: &SignedTreeHead{
 				TreeHead: TreeHead{
@@ -251,16 +236,7 @@ func TestSignedTreeHeadUnmarshalASCII(t *testing.T) {
 					TreeSize:  456,
 					RootHash:  testBuffer32,
 				},
-				SigIdent: []*SigIdent{
-					&SigIdent{
-						Signature: testBuffer64,
-						KeyHash:   testBuffer32,
-					},
-					&SigIdent{
-						Signature: testBuffer64,
-						KeyHash:   testBuffer32,
-					},
-				},
+				Signature: testBuffer64,
 			},
 		},
 	} {
@@ -436,7 +412,7 @@ func TestCosignatureRequestUnmarshalASCII(t *testing.T) {
 			description: "valid",
 			buf: bytes.NewBufferString(fmt.Sprintf(
 				"%s%s%x%s"+"%s%s%x%s",
-				Signature, Delim, testBuffer64[:], EOL,
+				Cosignature, Delim, testBuffer64[:], EOL,
 				KeyHash, Delim, testBuffer32[:], EOL,
 			)),
 			wantReq: &CosignatureRequest{
diff --git a/pkg/types/trunnel.go b/pkg/types/trunnel.go
index 268f6f7..5350c5b 100644
--- a/pkg/types/trunnel.go
+++ b/pkg/types/trunnel.go
@@ -10,6 +10,8 @@ const (
 	MessageSize = 8 + HashSize
 	// LeafSize is the number of bytes in a Trunnel-encoded leaf
 	LeafSize = MessageSize + SignatureSize + HashSize
+	// TreeHeadSize is the number of bytes in a Trunnel-encoded tree head
+	TreeHeadSize = 8 + 8 + HashSize + HashSize
 )
 
 // Marshal returns a Trunnel-encoded message
@@ -30,10 +32,11 @@ func (l *Leaf) Marshal() []byte {
 
 // Marshal returns a Trunnel-encoded tree head
 func (th *TreeHead) Marshal() []byte {
-	buf := make([]byte, 8+8+HashSize)
+	buf := make([]byte, TreeHeadSize)
 	binary.BigEndian.PutUint64(buf[0:8], th.Timestamp)
 	binary.BigEndian.PutUint64(buf[8:16], th.TreeSize)
-	copy(buf[16:], th.RootHash[:])
+	copy(buf[16:16+HashSize], th.RootHash[:])
+	copy(buf[16+HashSize:], th.KeyHash[:])
 	return buf
 }
 
diff --git a/pkg/types/trunnel_test.go b/pkg/types/trunnel_test.go
index 297578c..a3ae1ba 100644
--- a/pkg/types/trunnel_test.go
+++ b/pkg/types/trunnel_test.go
@@ -48,16 +48,18 @@ func TestMarshalLeaf(t *testing.T) {
 }
 
 func TestMarshalTreeHead(t *testing.T) {
-	description := "valid: timestamp 16909060, tree size 72623859790382856, root hash 0x00,0x01,..."
+	description := "valid: timestamp 16909060, tree size 72623859790382856, root hash & key hash 0x00,0x01,..."
 	th := &TreeHead{
 		Timestamp: 16909060,
 		TreeSize:  72623859790382856,
 		RootHash:  testBuffer32,
+		KeyHash:   testBuffer32,
 	}
 	want := bytes.Join([][]byte{
 		[]byte{0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04},
 		[]byte{0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08},
 		testBuffer32[:],
+		testBuffer32[:],
 	}, nil)
 	if got := th.Marshal(); !bytes.Equal(got, want) {
 		t.Errorf("got tree head\n\t%v\nbut wanted\n\t%v\nin test %q\n", got, want, description)
diff --git a/pkg/types/types.go b/pkg/types/types.go
index 96e2b18..bc58c98 100644
--- a/pkg/types/types.go
+++ b/pkg/types/types.go
@@ -32,78 +32,67 @@ func (e Endpoint) Path(components ...string) string {
 	return strings.Join(append(components, string(e)), "/")
 }
 
-// Leaf is the log's Merkle tree leaf.
 type Leaf struct {
 	Message
 	SigIdent
 }
 
-// Message is composed of a shard hint and a checksum.  The submitter selects
-// these values to fit the log's shard interval and the opaque data in question.
 type Message struct {
 	ShardHint uint64
 	Checksum  *[HashSize]byte
 }
 
-// SigIdent is composed of a signature-signer pair.  The signature is computed
-// over the Trunnel-serialized leaf message.  KeyHash identifies the signer.
 type SigIdent struct {
 	Signature *[SignatureSize]byte
 	KeyHash   *[HashSize]byte
 }
 
-// SignedTreeHead is composed of a tree head and a list of signature-signer
-// pairs.  Each signature is computed over the Trunnel-serialized tree head.
 type SignedTreeHead struct {
 	TreeHead
+	Signature *[SignatureSize]byte
+}
+
+type CosignedTreeHead struct {
+	SignedTreeHead
 	SigIdent []*SigIdent
 }
 
-// TreeHead is the log's tree head.
 type TreeHead struct {
 	Timestamp uint64
 	TreeSize  uint64
 	RootHash  *[HashSize]byte
+	KeyHash   *[HashSize]byte
 }
 
-// ConsistencyProof is a consistency proof that proves the log's append-only
-// property.
 type ConsistencyProof struct {
 	NewSize uint64
 	OldSize uint64
 	Path    []*[HashSize]byte
 }
 
-// InclusionProof is an inclusion proof that proves a leaf is included in the
-// log.
 type InclusionProof struct {
 	TreeSize  uint64
 	LeafIndex uint64
 	Path      []*[HashSize]byte
 }
 
-// LeafList is a list of leaves
 type LeafList []*Leaf
 
-// ConsistencyProofRequest is a get-consistency-proof request
 type ConsistencyProofRequest struct {
 	NewSize uint64
 	OldSize uint64
 }
 
-// InclusionProofRequest is a get-proof-by-hash request
 type InclusionProofRequest struct {
 	LeafHash *[HashSize]byte
 	TreeSize uint64
 }
 
-// LeavesRequest is a get-leaves request
 type LeavesRequest struct {
 	StartSize uint64
 	EndSize   uint64
 }
 
-// LeafRequest is an add-leaf request
 type LeafRequest struct {
 	Message
 	Signature       *[SignatureSize]byte
@@ -111,7 +100,6 @@ type LeafRequest struct {
 	DomainHint      string
 }
 
-// CosignatureRequest is an add-cosignature request
 type CosignatureRequest struct {
 	SigIdent
 }
@@ -123,17 +111,12 @@ func (th *TreeHead) Sign(signer crypto.Signer) (*SignedTreeHead, error) {
 		return nil, fmt.Errorf("Sign: %v", err)
 	}
 
-	sigident := SigIdent{
-		KeyHash:   Hash(signer.Public().(ed25519.PublicKey)[:]),
+	sth := &SignedTreeHead{
+		TreeHead:  *th,
 		Signature: &[SignatureSize]byte{},
 	}
-	copy(sigident.Signature[:], sig)
-	return &SignedTreeHead{
-		TreeHead: *th,
-		SigIdent: []*SigIdent{
-			&sigident,
-		},
-	}, nil
+	copy(sth.Signature[:], sig)
+	return sth, nil
 }
 
 // Verify verifies the tree head signature using the log's signature scheme