go/prf/subtle/aes_cmac_test.go

// 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 subtle

import (
	"encoding/hex"
	"encoding/json"
	"os"
	"testing"
)

func TestVectorsRFC4493(t *testing.T) {
	// Test vectors from RFC 4493.
	key, err := hex.DecodeString("2b7e151628aed2a6abf7158809cf4f3c")
	if err != nil {
		t.Errorf("Could not decode key: %v", err)
	}
	data, err := hex.DecodeString("6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52eff69f2445df4f9b17ad2b417be66c3710")
	if err != nil {
		t.Errorf("Could not decode data: %v", err)
	}
	expected := map[int]string{
		0:  "bb1d6929e95937287fa37d129b756746",
		16: "070a16b46b4d4144f79bdd9dd04a287c",
		40: "dfa66747de9ae63030ca32611497c827",
		64: "51f0bebf7e3b9d92fc49741779363cfe",
	}
	a, err := NewAESCMACPRF(key)
	if err != nil {
		t.Errorf("Could not create cmac.AES object: %v", err)
	}
	for l, e := range expected {
		output, err := a.ComputePRF(data[:l], 16)
		if err != nil {
			t.Errorf("Error computing AES-CMAC: %v", err)
		}
		if hex.EncodeToString(output) != e {
			t.Errorf("Computation and test vector differ. Computation: %q, Test Vector %q", hex.EncodeToString(output), e)
		}
	}
}

type testdata struct {
	Algorithm        string
	GeneratorVersion string
	NumberOfTests    uint32
	TestGroups       []*testgroup
}

type testgroup struct {
	KeySize uint32
	TagSize uint32
	Type    string
	Tests   []*testcase
}

type testcase struct {
	Comment string
	Key     string
	Msg     string
	Result  string
	Tag     string
	TcID    uint32
}

func TestVectorsWycheproof(t *testing.T) {
	f, err := os.Open(os.Getenv("TEST_SRCDIR") + "/wycheproof/testvectors/aes_cmac_test.json")
	if err != nil {
		t.Fatalf("cannot open file: %s, make sure that github.com/google/wycheproof is in your gopath", err)
	}
	parser := json.NewDecoder(f)
	data := new(testdata)
	if err := parser.Decode(data); err != nil {
		t.Fatalf("cannot decode test data: %s", err)
	}

	for _, g := range data.TestGroups {
		for _, tc := range g.Tests {
			key, err := hex.DecodeString(tc.Key)
			if err != nil || uint32(len(key))*8 != g.KeySize {
				t.Errorf("Could not decode key for test case %d (%s): %v", tc.TcID, tc.Comment, err)
				continue
			}
			msg, err := hex.DecodeString(tc.Msg)
			if err != nil {
				t.Errorf("Could not decode message for test case %d (%s): %v", tc.TcID, tc.Comment, err)
				continue
			}
			aes, err := NewAESCMACPRF(key)
			valid := tc.Result == "valid"
			if valid && err != nil {
				t.Errorf("Could not create cmac.AES for test case %d (%s): %v", tc.TcID, tc.Comment, err)
				continue
			}
			if !valid && err != nil {
				continue
			}
			if g.TagSize%8 != 0 {
				t.Errorf("Requested tag size for test case %d (%s) is not a multiple of 8, but %d", tc.TcID, tc.Comment, g.TagSize)
				continue
			}
			res, err := aes.ComputePRF(msg, g.TagSize/8)
			if valid && err != nil {
				t.Errorf("Could not compute AES-CMAC for test case %d (%s): %v", tc.TcID, tc.Comment, err)
				continue
			}
			if !valid && err != nil {
				continue
			}
			if valid && hex.EncodeToString(res) != tc.Tag {
				t.Errorf("Compute AES-CMAC and expected for test case %d (%s) do not match:\nComputed: %q\nExpected: %q", tc.TcID, tc.Comment, hex.EncodeToString(res), tc.Tag)
			}
			if !valid && hex.EncodeToString(res) == tc.Tag {
				t.Errorf("Compute AES-CMAC and invalid expected for test case %d (%s) match:\nComputed: %q\nExpected: %q", tc.TcID, tc.Comment, hex.EncodeToString(res), tc.Tag)
			}
		}
	}
}

func TestValidateAESCMACPRFParams(t *testing.T) {
	if err := ValidateAESCMACPRFParams(32); err != nil {
		t.Errorf("Unexpected error validating AES CMAC PRF Params: %v", err)
	}
	if err := ValidateAESCMACPRFParams(2); err == nil {
		t.Errorf("Unexpected validation of too short key for AES CMAC PRF Params")
	}
}

func TestKeyLength(t *testing.T) {
	if _, err := NewAESCMACPRF([]byte{0x01, 0x02}); err == nil {
		t.Errorf("Expected NewAESCMACPRF to fail on short key")
	}
	if _, err := NewAESCMACPRF([]byte{
		0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
		0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10}); err != nil {
		t.Errorf("Expected NewAESCMACPRF to work on 16 byte key")
	}
	if _, err := NewAESCMACPRF([]byte{
		0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
		0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10,
		0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
		0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10}); err != nil {
		t.Errorf("Expected NewAESCMACPRF to work on 32 byte key")
	}
}

func TestAESCMACPRFOutputLength(t *testing.T) {
	prf, err := NewAESCMACPRF([]byte{
		0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
		0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10,
		0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
		0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10})
	if err != nil {
		t.Errorf("Expected NewAESCMACPRF to work on 32 byte key")
	}
	for i := 0; i <= 16; i++ {
		output, err := prf.ComputePRF([]byte{0x01, 0x02}, uint32(i))
		if err != nil {
			t.Errorf("Expected to be able to compute AES CMAC PRF with %d output length", i)
		}
		if len(output) != i {
			t.Errorf("Expected AES CMAC PRF to compute %d bytes, got %d", i, len(output))
		}
	}
	for i := 17; i < 32; i++ {
		_, err := prf.ComputePRF([]byte{0x01, 0x02}, uint32(i))
		if err == nil {
			t.Errorf("Expected to not be able to compute AES CMAC PRF with %d output length", i)
		}
	}
}