Merge pull request #66 from qmuntal/iv

Ensure IV and Partial IV are not both present
veraison · May 20, 2022 · 2fccfc9 · 2fccfc9
2 parents cb68acd + 6042760
commit 2fccfc9
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Showing 6 changed files with 209 additions and 15 deletions.
diff --git a/headers.go b/headers.go
@@ -16,6 +16,8 @@ const (
 	HeaderLabelCritical          int64 = 2
 	HeaderLabelContentType       int64 = 3
 	HeaderLabelKeyID             int64 = 4
+	HeaderLabelIV                int64 = 5
+	HeaderLabelPartialIV         int64 = 6
 	HeaderLabelCounterSignature  int64 = 7
 	HeaderLabelCounterSignature0 int64 = 9
 	HeaderLabelX5Bag             int64 = 32
@@ -43,6 +45,9 @@ func (h ProtectedHeader) MarshalCBOR() ([]byte, error) {
 		if err = h.ensureCritical(); err != nil {
 			return nil, err
 		}
+		if err = ensureHeaderIV(h); err != nil {
+			return nil, fmt.Errorf("protected header: %w", err)
+		}
 		encoded, err = encMode.Marshal(map[interface{}]interface{}(h))
 		if err != nil {
 			return nil, err
@@ -83,6 +88,9 @@ func (h *ProtectedHeader) UnmarshalCBOR(data []byte) error {
 		if err := candidate.ensureCritical(); err != nil {
 			return err
 		}
+		if err := ensureHeaderIV(candidate); err != nil {
+			return fmt.Errorf("protected header: %w", err)
+		}
 
 		// cast to type Algorithm if `alg` presents
 		if alg, err := candidate.Algorithm(); err == nil {
@@ -170,6 +178,9 @@ func (h UnprotectedHeader) MarshalCBOR() ([]byte, error) {
 	if err := validateHeaderLabel(h); err != nil {
 		return nil, err
 	}
+	if err := ensureHeaderIV(h); err != nil {
+		return nil, fmt.Errorf("unprotected header: %w", err)
+	}
 	return encMode.Marshal(map[interface{}]interface{}(h))
 }
 
@@ -196,6 +207,9 @@ func (h *UnprotectedHeader) UnmarshalCBOR(data []byte) error {
 	if err := decMode.Unmarshal(data, &header); err != nil {
 		return err
 	}
+	if err := ensureHeaderIV(header); err != nil {
+		return fmt.Errorf("unprotected header: %w", err)
+	}
 	*h = header
 	return nil
 }
@@ -253,6 +267,23 @@ type Headers struct {
 	Unprotected UnprotectedHeader
 }
 
+// marshal encoded both headers.
+// It returns RawProtected and RawUnprotected if those are set.
+func (h *Headers) marshal() (cbor.RawMessage, cbor.RawMessage, error) {
+	if err := h.ensureIV(); err != nil {
+		return nil, nil, err
+	}
+	protected, err := h.MarshalProtected()
+	if err != nil {
+		return nil, nil, err
+	}
+	unprotected, err := h.MarshalUnprotected()
+	if err != nil {
+		return nil, nil, err
+	}
+	return protected, unprotected, nil
+}
+
 // MarshalProtected encodes the protected header.
 // RawProtected is returned if it is not set to nil.
 func (h *Headers) MarshalProtected() ([]byte, error) {
@@ -280,6 +311,9 @@ func (h *Headers) UnmarshalFromRaw() error {
 	if err := decMode.Unmarshal(h.RawUnprotected, &h.Unprotected); err != nil {
 		return fmt.Errorf("cbor: invalid unprotected header: %w", err)
 	}
+	if err := h.ensureIV(); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -331,6 +365,38 @@ func (h *Headers) ensureVerificationAlgorithm(alg Algorithm, external []byte) er
 	return err
 }
 
+// ensureIV ensures IV and Partial IV are not both present
+// in the protected and unprotected headers.
+// It does not check if they are both present within one header,
+// as it will be checked later on.
+//
+// Reference: https://datatracker.ietf.org/doc/html/rfc8152#section-3.1
+func (h *Headers) ensureIV() error {
+	if hasLabel(h.Protected, HeaderLabelIV) && hasLabel(h.Unprotected, HeaderLabelPartialIV) {
+		return errors.New("IV (protected) and PartialIV (unprotected) parameters must not both be present")
+	}
+	if hasLabel(h.Protected, HeaderLabelPartialIV) && hasLabel(h.Unprotected, HeaderLabelIV) {
+		return errors.New("IV (unprotected) and PartialIV (protected) parameters must not both be present")
+	}
+	return nil
+}
+
+// hasLabel returns true if h contains label.
+func hasLabel(h map[interface{}]interface{}, label interface{}) bool {
+	_, ok := h[label]
+	return ok
+}
+
+// ensureHeaderIV ensures IV and Partial IV are not both present in the header.
+//
+// Reference: https://datatracker.ietf.org/doc/html/rfc8152#section-3.1
+func ensureHeaderIV(h map[interface{}]interface{}) error {
+	if hasLabel(h, HeaderLabelIV) && hasLabel(h, HeaderLabelPartialIV) {
+		return errors.New("IV and PartialIV parameters must not both be present")
+	}
+	return nil
+}
+
 // validateHeaderLabel validates if all header labels are integers or strings.
 //
 //   label = int / tstr

diff --git a/headers_test.go b/headers_test.go
@@ -118,6 +118,14 @@ func TestProtectedHeader_MarshalCBOR(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "iv and partial iv present",
+			h: ProtectedHeader{
+				HeaderLabelIV:        "foo",
+				HeaderLabelPartialIV: "bar",
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -265,6 +273,13 @@ func TestProtectedHeader_UnmarshalCBOR(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "iv and partial iv present",
+			data: []byte{
+				0x4b, 0xa2, 0x5, 0x63, 0x66, 0x6f, 0x6f, 0x6, 0x63, 0x62, 0x61, 0x72,
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -517,6 +532,14 @@ func TestUnprotectedHeader_MarshalCBOR(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "iv and partial iv present",
+			h: UnprotectedHeader{
+				HeaderLabelIV:        "foo",
+				HeaderLabelPartialIV: "bar",
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -617,6 +640,13 @@ func TestUnprotectedHeader_UnmarshalCBOR(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "iv and partial iv present",
+			data: []byte{
+				0xa2, 0x5, 0x63, 0x66, 0x6f, 0x6f, 0x6, 0x63, 0x62, 0x61, 0x72,
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

diff --git a/sign.go b/sign.go
@@ -73,11 +73,7 @@ func (s *Signature) MarshalCBOR() ([]byte, error) {
 	if len(s.Signature) == 0 {
 		return nil, ErrEmptySignature
 	}
-	protected, err := s.Headers.MarshalProtected()
-	if err != nil {
-		return nil, err
-	}
-	unprotected, err := s.Headers.MarshalUnprotected()
+	protected, unprotected, err := s.Headers.marshal()
 	if err != nil {
 		return nil, err
 	}
@@ -329,11 +325,7 @@ func (m *SignMessage) MarshalCBOR() ([]byte, error) {
 	if len(m.Signatures) == 0 {
 		return nil, ErrNoSignatures
 	}
-	protected, err := m.Headers.MarshalProtected()
-	if err != nil {
-		return nil, err
-	}
-	unprotected, err := m.Headers.MarshalUnprotected()
+	protected, unprotected, err := m.Headers.marshal()
 	if err != nil {
 		return nil, err
 	}

diff --git a/sign1.go b/sign1.go
@@ -58,11 +58,7 @@ func (m *Sign1Message) MarshalCBOR() ([]byte, error) {
 	if len(m.Signature) == 0 {
 		return nil, ErrEmptySignature
 	}
-	protected, err := m.Headers.MarshalProtected()
-	if err != nil {
-		return nil, err
-	}
-	unprotected, err := m.Headers.MarshalUnprotected()
+	protected, unprotected, err := m.Headers.marshal()
 	if err != nil {
 		return nil, err
 	}

diff --git a/sign1_test.go b/sign1_test.go
@@ -130,6 +130,40 @@ func TestSign1Message_MarshalCBOR(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "protected has IV and unprotected has PartialIV error",
+			m: &Sign1Message{
+				Headers: Headers{
+					Protected: ProtectedHeader{
+						HeaderLabelAlgorithm: AlgorithmES256,
+						HeaderLabelIV:        "",
+					},
+					Unprotected: UnprotectedHeader{
+						HeaderLabelPartialIV: "",
+					},
+				},
+				Payload:   []byte("foo"),
+				Signature: []byte("bar"),
+			},
+			wantErr: true,
+		},
+		{
+			name: "protected has PartialIV and unprotected has IV error",
+			m: &Sign1Message{
+				Headers: Headers{
+					Protected: ProtectedHeader{
+						HeaderLabelAlgorithm: AlgorithmES256,
+						HeaderLabelPartialIV: "",
+					},
+					Unprotected: UnprotectedHeader{
+						HeaderLabelIV: "",
+					},
+				},
+				Payload:   []byte("foo"),
+				Signature: []byte("bar"),
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -324,6 +358,30 @@ func TestSign1Message_UnmarshalCBOR(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "protected has IV and unprotected has PartialIV",
+			data: []byte{
+				0xd2, // tag
+				0x84,
+				0x46, 0xa1, 0x5, 0x63, 0x66, 0x6f, 0x6f, // protected
+				0xa1, 0x6, 0x63, 0x62, 0x61, 0x72, // unprotected
+				0xf6,                   // payload
+				0x43, 0x62, 0x61, 0x72, // signature
+			},
+			wantErr: true,
+		},
+		{
+			name: "protected has PartialIV and unprotected has IV",
+			data: []byte{
+				0xd2, // tag
+				0x84,
+				0x46, 0xa1, 0x6, 0x63, 0x66, 0x6f, 0x6f, // protected
+				0xa1, 0x5, 0x63, 0x62, 0x61, 0x72, // unprotected
+				0xf6,                   // payload
+				0x43, 0x62, 0x61, 0x72, // signature
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

diff --git a/sign_test.go b/sign_test.go
@@ -102,6 +102,38 @@ func TestSignature_MarshalCBOR(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "protected has IV and unprotected has PartialIV error",
+			s: &Signature{
+				Headers: Headers{
+					Protected: ProtectedHeader{
+						HeaderLabelAlgorithm: AlgorithmES256,
+						HeaderLabelIV:        "",
+					},
+					Unprotected: UnprotectedHeader{
+						HeaderLabelPartialIV: "",
+					},
+				},
+				Signature: []byte("bar"),
+			},
+			wantErr: true,
+		},
+		{
+			name: "protected has PartialIV and unprotected has IV error",
+			s: &Signature{
+				Headers: Headers{
+					Protected: ProtectedHeader{
+						HeaderLabelAlgorithm: AlgorithmES256,
+						HeaderLabelPartialIV: "",
+					},
+					Unprotected: UnprotectedHeader{
+						HeaderLabelIV: "",
+					},
+				},
+				Signature: []byte("bar"),
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -227,6 +259,26 @@ func TestSignature_UnmarshalCBOR(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "protected has IV and unprotected has PartialIV",
+			data: []byte{
+				0x83,
+				0x46, 0xa1, 0x5, 0x63, 0x66, 0x6f, 0x6f, // protected
+				0xa1, 0x6, 0x63, 0x62, 0x61, 0x72, // unprotected
+				0x43, 0x62, 0x61, 0x72, // signature
+			},
+			wantErr: true,
+		},
+		{
+			name: "protected has PartialIV and unprotected has IV",
+			data: []byte{
+				0x83,
+				0x46, 0xa1, 0x6, 0x63, 0x66, 0x6f, 0x6f, // protected
+				0xa1, 0x5, 0x63, 0x62, 0x61, 0x72, // unprotected
+				0x43, 0x62, 0x61, 0x72, // signature
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {