// Copyright 2020 Google LLC
//
// 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 streamingaead_test

import (
	"bytes"
	"encoding/hex"
	"fmt"
	"testing"

	"github.com/google/go-cmp/cmp"
	"google.golang.org/protobuf/proto"
	"github.com/google/tink/go/core/registry"
	"github.com/google/tink/go/internal/internalregistry"
	"github.com/google/tink/go/streamingaead/subtle"
	"github.com/google/tink/go/subtle/random"
	"github.com/google/tink/go/testutil"
	gcmhkdfpb "github.com/google/tink/go/proto/aes_gcm_hkdf_streaming_go_proto"
	commonpb "github.com/google/tink/go/proto/common_go_proto"
	tinkpb "github.com/google/tink/go/proto/tink_go_proto"
)

var aesGCMHKDFKeySizes = []uint32{16, 32}

func TestAESGCMHKDFGetPrimitiveBasic(t *testing.T) {
	keyManager, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}
	for _, keySize := range aesGCMHKDFKeySizes {
		key := testutil.NewAESGCMHKDFKey(testutil.AESGCMHKDFKeyVersion, keySize, keySize, commonpb.HashType_SHA256, 4096)
		serializedKey, err := proto.Marshal(key)
		if err != nil {
			t.Errorf("failed to marshal key: %s", err)
		}
		p, err := keyManager.Primitive(serializedKey)
		if err != nil {
			t.Errorf("unexpected error: %s", err)
		}
		if err := validatePrimitive(p, key); err != nil {
			t.Errorf("%s", err)
		}
	}
}

func TestAESGCMHKDFGetPrimitiveWithInvalidInput(t *testing.T) {
	keyManager, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}

	testKeys := genInvalidAESGCMHKDFKeys()
	for i := 0; i < len(testKeys); i++ {
		serializedKey, err := proto.Marshal(testKeys[i])
		if err != nil {
			t.Errorf("failed to marshal key: %s", err)
		}
		if _, err := keyManager.Primitive(serializedKey); err == nil {
			t.Errorf("expect an error in test case %d", i)
		}
	}

	if _, err := keyManager.Primitive(nil); err == nil {
		t.Errorf("expect an error when input is nil")
	}
	if _, err := keyManager.Primitive([]byte{}); err == nil {
		t.Errorf("expect an error when input is empty")
	}
}

func TestAESGCMHKDFNewKeyMultipleTimes(t *testing.T) {
	keyManager, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}
	format := testutil.NewAESGCMHKDFKeyFormat(32, 32, commonpb.HashType_SHA256, 4096)
	serializedFormat, err := proto.Marshal(format)
	if err != nil {
		t.Errorf("failed to marshal key: %s", err)
	}
	keys := make(map[string]struct{})
	n := 26
	for i := 0; i < n; i++ {
		key, _ := keyManager.NewKey(serializedFormat)
		serializedKey, err := proto.Marshal(key)
		if err != nil {
			t.Errorf("failed to marshal key: %s", err)
		}
		keys[string(serializedKey)] = struct{}{}

		keyData, _ := keyManager.NewKeyData(serializedFormat)
		serializedKey = keyData.Value
		keys[string(serializedKey)] = struct{}{}
	}
	if len(keys) != n*2 {
		t.Errorf("key is repeated")
	}
}

func TestAESGCMHKDFNewKeyBasic(t *testing.T) {
	keyManager, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}
	for _, keySize := range aesGCMHKDFKeySizes {
		format := testutil.NewAESGCMHKDFKeyFormat(
			keySize,
			keySize,
			commonpb.HashType_SHA256,
			4096,
		)
		serializedFormat, err := proto.Marshal(format)
		if err != nil {
			t.Errorf("failed to marshal key: %s", err)
		}
		m, err := keyManager.NewKey(serializedFormat)
		if err != nil {
			t.Errorf("unexpected error: %s", err)
		}
		key := m.(*gcmhkdfpb.AesGcmHkdfStreamingKey)
		if err := validateAESGCMHKDFKey(key, format); err != nil {
			t.Errorf("%s", err)
		}
	}
}

func TestAESGCMHKDFNewKeyWithInvalidInput(t *testing.T) {
	keyManager, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}
	// bad format
	badFormats := genInvalidAESGCMHKDFKeyFormats()
	for i := 0; i < len(badFormats); i++ {
		serializedFormat, err := proto.Marshal(badFormats[i])
		if err != nil {
			t.Errorf("failed to marshal key: %s", err)
		}
		if _, err := keyManager.NewKey(serializedFormat); err == nil {
			t.Errorf("expect an error in test case %d", i)
		}
	}
	// nil
	if _, err := keyManager.NewKey(nil); err == nil {
		t.Errorf("expect an error when input is nil")
	}
	// empty array
	if _, err := keyManager.NewKey([]byte{}); err == nil {
		t.Errorf("expect an error when input is empty")
	}
}

func TestAESGCMHKDFNewKeyDataBasic(t *testing.T) {
	keyManager, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}
	for _, keySize := range aesGCMHKDFKeySizes {
		format := testutil.NewAESGCMHKDFKeyFormat(
			keySize,
			keySize,
			commonpb.HashType_SHA256,
			4096,
		)
		serializedFormat, err := proto.Marshal(format)
		if err != nil {
			t.Errorf("failed to marshal key: %s", err)
		}
		keyData, err := keyManager.NewKeyData(serializedFormat)
		if err != nil {
			t.Errorf("unexpected error: %s", err)
		}
		if keyData.TypeUrl != testutil.AESGCMHKDFTypeURL {
			t.Errorf("incorrect type url")
		}
		if keyData.KeyMaterialType != tinkpb.KeyData_SYMMETRIC {
			t.Errorf("incorrect key material type")
		}
		key := new(gcmhkdfpb.AesGcmHkdfStreamingKey)
		if err := proto.Unmarshal(keyData.Value, key); err != nil {
			t.Errorf("incorrect key value")
		}
		if err := validateAESGCMHKDFKey(key, format); err != nil {
			t.Errorf("%s", err)
		}
	}
}

func TestAESGCMHKDFNewKeyDataWithInvalidInput(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}
	badFormats := genInvalidAESGCMHKDFKeyFormats()
	for i := 0; i < len(badFormats); i++ {
		serializedFormat, err := proto.Marshal(badFormats[i])
		if err != nil {
			t.Errorf("failed to marshal key: %s", err)
		}
		if _, err := km.NewKeyData(serializedFormat); err == nil {
			t.Errorf("expect an error in test case %d", i)
		}
	}
	// nil input
	if _, err := km.NewKeyData(nil); err == nil {
		t.Errorf("expect an error when input is nil")
	}
	// empty input
	if _, err := km.NewKeyData([]byte{}); err == nil {
		t.Errorf("expect an error when input is empty")
	}
}

func TestAESGCMHKDFDoesSupport(t *testing.T) {
	keyManager, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}
	if !keyManager.DoesSupport(testutil.AESGCMHKDFTypeURL) {
		t.Errorf("AESGCMHKDFKeyManager must support %s", testutil.AESGCMHKDFTypeURL)
	}
	if keyManager.DoesSupport("some bad type") {
		t.Errorf("AESGCMHKDFKeyManager must support only %s", testutil.AESGCMHKDFTypeURL)
	}
}

func TestAESGCMHKDFTypeURL(t *testing.T) {
	keyManager, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Errorf("cannot obtain AES-GCM-HKDF key manager: %s", err)
	}
	if keyManager.TypeURL() != testutil.AESGCMHKDFTypeURL {
		t.Errorf("incorrect key type")
	}
}

func TestAESGCMHKDFKeyMaterialType(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.AESGCMHKDFTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}
	if got, want := keyManager.KeyMaterialType(), tinkpb.KeyData_SYMMETRIC; got != want {
		t.Errorf("KeyMaterialType() = %v, want %v", got, want)
	}
}

func TestAESGCMHKDFDeriveKey(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.AESGCMHKDFTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}
	for _, keySize := range []uint32{16, 32} {
		for _, derivedKeySize := range []uint32{16, 32} {
			keyFormat := &gcmhkdfpb.AesGcmHkdfStreamingKeyFormat{
				Version: testutil.AESGCMHKDFKeyVersion,
				Params: &gcmhkdfpb.AesGcmHkdfStreamingParams{
					CiphertextSegmentSize: derivedKeySize + subtle.AESGCMHKDFNoncePrefixSizeInBytes + subtle.AESGCMHKDFTagSizeInBytes + 2,
					DerivedKeySize:        derivedKeySize,
					HkdfHashType:          commonpb.HashType_SHA256,
				},
				KeySize: keySize,
			}
			serializedKeyFormat, err := proto.Marshal(keyFormat)
			if err != nil {
				t.Fatalf("proto.Marshal(%v) err = %v, want nil", keyFormat, err)
			}
			rand := random.GetRandomBytes(keySize)
			buf := &bytes.Buffer{}
			buf.Write(rand) // never returns a non-nil error
			k, err := keyManager.DeriveKey(serializedKeyFormat, buf)
			if err != nil {
				t.Fatalf("keyManager.DeriveKey() err = %v, want nil", err)
			}
			key := k.(*gcmhkdfpb.AesGcmHkdfStreamingKey)
			if got, want := len(key.GetKeyValue()), int(keySize); got != want {
				t.Errorf("key length = %d, want %d", got, want)
			}
			if diff := cmp.Diff(key.GetKeyValue(), rand); diff != "" {
				t.Errorf("incorrect derived key: diff = %v", diff)
			}
		}
	}
}

func TestAESGCMHKDFDeriveKeyFailsWithInvalidKeyFormats(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.AESGCMHKDFTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}

	validKeyFormat := &gcmhkdfpb.AesGcmHkdfStreamingKeyFormat{
		Version: testutil.AESGCMHKDFKeyVersion,
		Params: &gcmhkdfpb.AesGcmHkdfStreamingParams{
			CiphertextSegmentSize: 16 + subtle.AESGCMHKDFNoncePrefixSizeInBytes + subtle.AESGCMHKDFTagSizeInBytes + 2,
			DerivedKeySize:        16,
			HkdfHashType:          commonpb.HashType_SHA256,
		},
		KeySize: 16,
	}
	serializedValidKeyFormat, err := proto.Marshal(validKeyFormat)
	if err != nil {
		t.Fatalf("proto.Marshal(%v) err = %v, want nil", validKeyFormat, err)
	}
	buf := bytes.NewBuffer(random.GetRandomBytes(validKeyFormat.KeySize))
	if _, err := keyManager.DeriveKey(serializedValidKeyFormat, buf); err != nil {
		t.Fatalf("keyManager.DeriveKey() err = %v, want nil", err)
	}

	for _, test := range []struct {
		name                  string
		version               uint32
		keySize               uint32
		ciphertextSegmentSize uint32
		derivedKeySize        uint32
		hkdfHashType          commonpb.HashType
	}{
		{
			name:                  "invalid version",
			version:               10,
			keySize:               validKeyFormat.KeySize,
			ciphertextSegmentSize: validKeyFormat.Params.CiphertextSegmentSize,
			derivedKeySize:        validKeyFormat.Params.DerivedKeySize,
			hkdfHashType:          validKeyFormat.Params.HkdfHashType,
		},
		{
			name:                  "invalid key size",
			version:               validKeyFormat.Version,
			keySize:               10,
			ciphertextSegmentSize: validKeyFormat.Params.CiphertextSegmentSize,
			derivedKeySize:        validKeyFormat.Params.DerivedKeySize,
			hkdfHashType:          validKeyFormat.Params.HkdfHashType,
		},
		{
			name:                  "invalid ciphertext segment size",
			version:               validKeyFormat.Version,
			keySize:               validKeyFormat.KeySize,
			ciphertextSegmentSize: 10,
			derivedKeySize:        validKeyFormat.Params.DerivedKeySize,
			hkdfHashType:          validKeyFormat.Params.HkdfHashType,
		},
		{
			name:                  "invalid ciphertext segment size",
			version:               validKeyFormat.Version,
			keySize:               validKeyFormat.KeySize,
			ciphertextSegmentSize: 2147483648,
			derivedKeySize:        validKeyFormat.Params.DerivedKeySize,
			hkdfHashType:          validKeyFormat.Params.HkdfHashType,
		},
		{
			name:                  "invalid derived key size",
			version:               validKeyFormat.Version,
			keySize:               validKeyFormat.KeySize,
			ciphertextSegmentSize: validKeyFormat.Params.CiphertextSegmentSize,
			derivedKeySize:        10,
			hkdfHashType:          validKeyFormat.Params.HkdfHashType,
		},
		{
			name:                  "invalid HKDF hash type",
			version:               validKeyFormat.Version,
			keySize:               validKeyFormat.KeySize,
			ciphertextSegmentSize: validKeyFormat.Params.CiphertextSegmentSize,
			derivedKeySize:        validKeyFormat.Params.DerivedKeySize,
			hkdfHashType:          commonpb.HashType_UNKNOWN_HASH,
		},
		{
			name:                  "invalid HKDF hash type",
			version:               validKeyFormat.Version,
			keySize:               validKeyFormat.KeySize,
			ciphertextSegmentSize: validKeyFormat.Params.CiphertextSegmentSize,
			derivedKeySize:        validKeyFormat.Params.DerivedKeySize,
			hkdfHashType:          commonpb.HashType_SHA224,
		},
		{
			name:                  "invalid HKDF hash type",
			version:               validKeyFormat.Version,
			keySize:               validKeyFormat.KeySize,
			ciphertextSegmentSize: validKeyFormat.Params.CiphertextSegmentSize,
			derivedKeySize:        validKeyFormat.Params.DerivedKeySize,
			hkdfHashType:          commonpb.HashType_SHA384,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			keyFormat, err := proto.Marshal(&gcmhkdfpb.AesGcmHkdfStreamingKeyFormat{
				Version: test.version,
				KeySize: test.keySize,
				Params: &gcmhkdfpb.AesGcmHkdfStreamingParams{
					CiphertextSegmentSize: test.ciphertextSegmentSize,
					DerivedKeySize:        test.derivedKeySize,
					HkdfHashType:          test.hkdfHashType,
				},
			})
			if err != nil {
				t.Fatalf("proto.Marshal() err = %v, want nil", err)
			}
			buf := bytes.NewBuffer(random.GetRandomBytes(test.keySize))
			if _, err := keyManager.DeriveKey(keyFormat, buf); err == nil {
				t.Errorf("keyManager.DeriveKey() err = nil, want non-nil")
			}
		})
	}
}

func TestAESGCMHKDFDeriveKeyFailsWithMalformedKeyFormats(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.AESGCMHKDFTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}
	// Proto messages start with a VarInt, which always ends with a byte with the
	// MSB unset, so 0x80 is invalid.
	invalidSerialization, err := hex.DecodeString("80")
	if err != nil {
		t.Errorf("hex.DecodeString() err = %v, want nil", err)
	}
	for _, test := range []struct {
		name      string
		keyFormat []byte
	}{
		{
			name:      "nil",
			keyFormat: nil,
		},
		{
			name:      "empty",
			keyFormat: []byte{},
		},
		{
			name:      "invalid serialization",
			keyFormat: invalidSerialization,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			buf := bytes.NewBuffer(random.GetRandomBytes(32))
			if _, err := keyManager.DeriveKey(test.keyFormat, buf); err == nil {
				t.Errorf("keyManager.DeriveKey() err = nil, want non-nil")
			}
		})
	}
}

func TestAESGCMHKDFDeriveKeyFailsWithInsufficientRandomness(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.AESGCMHKDFTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.AESGCMHKDFTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}
	keyFormat, err := proto.Marshal(&gcmhkdfpb.AesGcmHkdfStreamingKeyFormat{
		Version: testutil.AESGCMHKDFKeyVersion,
		Params: &gcmhkdfpb.AesGcmHkdfStreamingParams{
			CiphertextSegmentSize: 16 + subtle.AESGCMHKDFNoncePrefixSizeInBytes + subtle.AESGCMHKDFTagSizeInBytes + 2,
			DerivedKeySize:        16,
			HkdfHashType:          commonpb.HashType_SHA256,
		},
		KeySize: 16,
	})
	if err != nil {
		t.Fatalf("proto.Marshal(%v) err = %v, want nil", keyFormat, err)
	}
	{
		buf := bytes.NewBuffer(random.GetRandomBytes(16))
		if _, err := keyManager.DeriveKey(keyFormat, buf); err != nil {
			t.Errorf("keyManager.DeriveKey() err = %v, want nil", err)
		}
	}
	{
		insufficientBuf := bytes.NewBuffer(random.GetRandomBytes(15))
		if _, err := keyManager.DeriveKey(keyFormat, insufficientBuf); err == nil {
			t.Errorf("keyManager.DeriveKey() err = nil, want non-nil")
		}
	}
}

func genInvalidAESGCMHKDFKeys() []proto.Message {
	return []proto.Message{
		// not a AESGCMHKDFKey
		testutil.NewAESGCMHKDFKeyFormat(32, 32, commonpb.HashType_SHA256, 4096),
		// bad key size
		testutil.NewAESGCMHKDFKey(testutil.AESGCMKeyVersion, 17, 16, commonpb.HashType_SHA256, 4096),
		testutil.NewAESGCMHKDFKey(testutil.AESGCMKeyVersion, 16, 17, commonpb.HashType_SHA256, 4096),
		testutil.NewAESGCMHKDFKey(testutil.AESGCMKeyVersion, 33, 33, commonpb.HashType_SHA256, 4096),
		// bad version
		testutil.NewAESGCMHKDFKey(testutil.AESGCMKeyVersion+1, 16, 16, commonpb.HashType_SHA256, 4096),
	}
}

func genInvalidAESGCMHKDFKeyFormats() []proto.Message {
	return []proto.Message{
		// not AESGCMKeyFormat
		testutil.NewAESGCMHKDFKey(testutil.AESGCMKeyVersion, 16, 16, commonpb.HashType_SHA256, 16),
		// invalid key size
		testutil.NewAESGCMHKDFKeyFormat(17, 16, commonpb.HashType_SHA256, 4096),
		testutil.NewAESGCMHKDFKeyFormat(16, 17, commonpb.HashType_SHA256, 4096),
		testutil.NewAESGCMHKDFKeyFormat(33, 33, commonpb.HashType_SHA256, 4096),
	}
}

func validateAESGCMHKDFKey(key *gcmhkdfpb.AesGcmHkdfStreamingKey, format *gcmhkdfpb.AesGcmHkdfStreamingKeyFormat) error {
	if uint32(len(key.KeyValue)) != format.KeySize {
		return fmt.Errorf("incorrect key size")
	}
	if key.Version != testutil.AESGCMKeyVersion {
		return fmt.Errorf("incorrect key version")
	}
	if key.Params.CiphertextSegmentSize != format.Params.CiphertextSegmentSize {
		return fmt.Errorf("incorrect ciphertext segment size")
	}
	if key.Params.DerivedKeySize != format.Params.DerivedKeySize {
		return fmt.Errorf("incorrect derived key size")
	}
	if key.Params.HkdfHashType != format.Params.HkdfHashType {
		return fmt.Errorf("incorrect HKDF hash type")
	}
	// try to encrypt and decrypt
	p, err := subtle.NewAESGCMHKDF(
		key.KeyValue,
		key.Params.HkdfHashType.String(),
		int(key.Params.DerivedKeySize),
		int(key.Params.CiphertextSegmentSize),
		0,
	)
	if err != nil {
		return fmt.Errorf("invalid key")
	}
	return validatePrimitive(p, key)
}

func validatePrimitive(p interface{}, key *gcmhkdfpb.AesGcmHkdfStreamingKey) error {
	cipher := p.(*subtle.AESGCMHKDF)
	if !bytes.Equal(cipher.MainKey, key.KeyValue) {
		return fmt.Errorf("main key and primitive don't match")
	}
	return encryptDecrypt(cipher, cipher, 32, 32)
}