Include stat in Verity hash

PiperOrigin-RevId: 336395445

2 files changed, 322 insertions, 75 deletions

diff --git a/pkg/merkletree/merkletree.go b/pkg/merkletree/merkletree.go
index ccef83259..a6e698f57 100644
--- a/pkg/merkletree/merkletree.go
+++ b/pkg/merkletree/merkletree.go
@@ -123,45 +123,87 @@ func (layout Layout) blockOffset(level int, index int64) int64 {
 	return layout.levelOffset[level] + index*layout.blockSize
 }
 
+// VerityDescriptor is a struct that is serialized and hashed to get a file's
+// root hash, which contains the root hash of the raw content and the file's
+// meatadata.
+type VerityDescriptor struct {
+	Name     string
+	Mode     uint32
+	UID      uint32
+	GID      uint32
+	RootHash []byte
+}
+
+func (d *VerityDescriptor) String() string {
+	return fmt.Sprintf("Name: %s, Mode: %d, UID: %d, GID: %d, RootHash: %v", d.Name, d.Mode, d.UID, d.GID, d.RootHash)
+}
+
+// GenerateParams contains the parameters used to generate a Merkle tree.
+type GenerateParams struct {
+	// File is a reader of the file to be hashed.
+	File io.ReadSeeker
+	// Size is the size of the file.
+	Size int64
+	// Name is the name of the target file.
+	Name string
+	// Mode is the mode of the target file.
+	Mode uint32
+	// UID is the user ID of the target file.
+	UID uint32
+	// GID is the group ID of the target file.
+	GID uint32
+	// TreeReader is a reader for the Merkle tree.
+	TreeReader io.ReadSeeker
+	// TreeWriter is a writer for the Merkle tree.
+	TreeWriter io.WriteSeeker
+	// DataAndTreeInSameFile is true if data and Merkle tree are in the same
+	// file, or false if Merkle tree is a separate file from data.
+	DataAndTreeInSameFile bool
+}
+
 // Generate constructs a Merkle tree for the contents of data. The output is
 // written to treeWriter. The treeReader should be able to read the tree after
 // it has been written. That is, treeWriter and treeReader should point to the
 // same underlying data but have separate cursors.
+//
+// Generate returns a hash of descriptor. The descriptor contains the file
+// metadata and the hash from file content.
+//
 // Generate will modify the cursor for data, but always restores it to its
 // original position upon exit. The cursor for tree is modified and not
 // restored.
-func Generate(data io.ReadSeeker, dataSize int64, treeReader io.ReadSeeker, treeWriter io.WriteSeeker, dataAndTreeInSameFile bool) ([]byte, error) {
-	layout := InitLayout(dataSize, dataAndTreeInSameFile)
+func Generate(params *GenerateParams) ([]byte, error) {
+	layout := InitLayout(params.Size, params.DataAndTreeInSameFile)
 
-	numBlocks := (dataSize + layout.blockSize - 1) / layout.blockSize
+	numBlocks := (params.Size + layout.blockSize - 1) / layout.blockSize
 
 	// If the data is in the same file as the tree, zero pad the last data
 	// block.
-	bytesInLastBlock := dataSize % layout.blockSize
-	if dataAndTreeInSameFile && bytesInLastBlock != 0 {
+	bytesInLastBlock := params.Size % layout.blockSize
+	if params.DataAndTreeInSameFile && bytesInLastBlock != 0 {
 		zeroBuf := make([]byte, layout.blockSize-bytesInLastBlock)
-		if _, err := treeWriter.Seek(0, io.SeekEnd); err != nil && err != io.EOF {
+		if _, err := params.TreeWriter.Seek(0, io.SeekEnd); err != nil && err != io.EOF {
 			return nil, err
 		}
-		if _, err := treeWriter.Write(zeroBuf); err != nil {
+		if _, err := params.TreeWriter.Write(zeroBuf); err != nil {
 			return nil, err
 		}
 	}
 
 	// Store the current offset, so we can set it back once verification
 	// finishes.
-	origOffset, err := data.Seek(0, io.SeekCurrent)
+	origOffset, err := params.File.Seek(0, io.SeekCurrent)
 	if err != nil {
 		return nil, err
 	}
-	defer data.Seek(origOffset, io.SeekStart)
+	defer params.File.Seek(origOffset, io.SeekStart)
 
 	// Read from the beginning of both data and treeReader.
-	if _, err := data.Seek(0, io.SeekStart); err != nil && err != io.EOF {
+	if _, err := params.File.Seek(0, io.SeekStart); err != nil && err != io.EOF {
 		return nil, err
 	}
 
-	if _, err := treeReader.Seek(0, io.SeekStart); err != nil && err != io.EOF {
+	if _, err := params.TreeReader.Seek(0, io.SeekStart); err != nil && err != io.EOF {
 		return nil, err
 	}
 
@@ -176,11 +218,11 @@ func Generate(data io.ReadSeeker, dataSize int64, treeReader io.ReadSeeker, tree
 			if level == 0 {
 				// Read data block from the target file since level 0 includes hashes
 				// of blocks in the input data.
-				n, err = data.Read(buf)
+				n, err = params.File.Read(buf)
 			} else {
 				// Read data block from the tree file since levels higher than 0 are
 				// hashing the lower level hashes.
-				n, err = treeReader.Read(buf)
+				n, err = params.TreeReader.Read(buf)
 			}
 
 			// err is populated as long as the bytes read is smaller than the buffer
@@ -200,7 +242,7 @@ func Generate(data io.ReadSeeker, dataSize int64, treeReader io.ReadSeeker, tree
 			}
 
 			// Write the generated hash to the end of the tree file.
-			if _, err = treeWriter.Write(digest[:]); err != nil {
+			if _, err = params.TreeWriter.Write(digest[:]); err != nil {
 				return nil, err
 			}
 		}
@@ -208,45 +250,124 @@ func Generate(data io.ReadSeeker, dataSize int64, treeReader io.ReadSeeker, tree
 		// remaining of the last block. But no need to do so for root.
 		if level != layout.rootLevel() && numBlocks%layout.hashesPerBlock() != 0 {
 			zeroBuf := make([]byte, layout.blockSize-(numBlocks%layout.hashesPerBlock())*layout.digestSize)
-			if _, err := treeWriter.Write(zeroBuf[:]); err != nil {
+			if _, err := params.TreeWriter.Write(zeroBuf[:]); err != nil {
 				return nil, err
 			}
 		}
 		numBlocks = (numBlocks + layout.hashesPerBlock() - 1) / layout.hashesPerBlock()
 	}
-	return root, nil
+	descriptor := VerityDescriptor{
+		Name:     params.Name,
+		Mode:     params.Mode,
+		UID:      params.UID,
+		GID:      params.GID,
+		RootHash: root,
+	}
+	ret := sha256.Sum256([]byte(descriptor.String()))
+	return ret[:], nil
+}
+
+// VerifyParams contains the params used to verify a portion of a file against
+// a Merkle tree.
+type VerifyParams struct {
+	// Out will be filled with verified data.
+	Out io.Writer
+	// File is a handler on the file to be verified.
+	File io.ReadSeeker
+	// tree is a handler on the Merkle tree used to verify file.
+	Tree io.ReadSeeker
+	// Size is the size of the file.
+	Size int64
+	// Name is the name of the target file.
+	Name string
+	// Mode is the mode of the target file.
+	Mode uint32
+	// UID is the user ID of the target file.
+	UID uint32
+	// GID is the group ID of the target file.
+	GID uint32
+	// ReadOffset is the offset of the data range to be verified.
+	ReadOffset int64
+	// ReadSize is the size of the data range to be verified.
+	ReadSize int64
+	// ExpectedRoot is a trusted hash for the file. It is compared with the
+	// calculated root hash to verify the content.
+	ExpectedRoot []byte
+	// DataAndTreeInSameFile is true if data and Merkle tree are in the same
+	// file, or false if Merkle tree is a separate file from data.
+	DataAndTreeInSameFile bool
+}
+
+// verifyDescriptor generates a hash from descriptor, and compares it with
+// expectedRoot.
+func verifyDescriptor(descriptor VerityDescriptor, expectedRoot []byte) error {
+	h := sha256.Sum256([]byte(descriptor.String()))
+	if !bytes.Equal(h[:], expectedRoot) {
+		return fmt.Errorf("unexpected root hash")
+	}
+	return nil
+}
+
+// verifyMetadata verifies the metadata by hashing a descriptor that contains
+// the metadata and compare the generated hash with expectedRoot.
+//
+// For verifyMetadata, params.data is not needed. It only accesses params.tree
+// for the raw root hash.
+func verifyMetadata(params *VerifyParams, layout Layout) error {
+	if _, err := params.Tree.Seek(layout.blockOffset(layout.rootLevel(), 0 /* index */), io.SeekStart); err != nil {
+		return fmt.Errorf("failed to seek to root hash: %w", err)
+	}
+	root := make([]byte, layout.digestSize)
+	if _, err := params.Tree.Read(root); err != nil {
+		return fmt.Errorf("failed to read root hash: %w", err)
+	}
+	descriptor := VerityDescriptor{
+		Name:     params.Name,
+		Mode:     params.Mode,
+		UID:      params.UID,
+		GID:      params.GID,
+		RootHash: root,
+	}
+	return verifyDescriptor(descriptor, params.ExpectedRoot)
 }
 
 // Verify verifies the content read from data with offset. The content is
 // verified against tree. If content spans across multiple blocks, each block is
 // verified. Verification fails if the hash of the data does not match the tree
 // at any level, or if the final root hash does not match expectedRoot.
-// Once the data is verified, it will be written using w.
+// Once the data is verified, it will be written using params.Out.
+//
+// Verify checks for both target file content and metadata. If readSize is 0,
+// only metadata is checked.
+//
 // Verify will modify the cursor for data, but always restores it to its
 // original position upon exit. The cursor for tree is modified and not
 // restored.
-func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset int64, readSize int64, expectedRoot []byte, dataAndTreeInSameFile bool) (int64, error) {
-	if readSize <= 0 {
-		return 0, fmt.Errorf("Unexpected read size: %d", readSize)
+func Verify(params *VerifyParams) (int64, error) {
+	if params.ReadSize < 0 {
+		return 0, fmt.Errorf("unexpected read size: %d", params.ReadSize)
+	}
+	layout := InitLayout(int64(params.Size), params.DataAndTreeInSameFile)
+	if params.ReadSize == 0 {
+		return 0, verifyMetadata(params, layout)
 	}
-	layout := InitLayout(int64(dataSize), dataAndTreeInSameFile)
 
 	// Calculate the index of blocks that includes the target range in input
 	// data.
-	firstDataBlock := readOffset / layout.blockSize
-	lastDataBlock := (readOffset + readSize - 1) / layout.blockSize
+	firstDataBlock := params.ReadOffset / layout.blockSize
+	lastDataBlock := (params.ReadOffset + params.ReadSize - 1) / layout.blockSize
 
 	// Store the current offset, so we can set it back once verification
 	// finishes.
-	origOffset, err := data.Seek(0, io.SeekCurrent)
+	origOffset, err := params.File.Seek(0, io.SeekCurrent)
 	if err != nil {
-		return 0, fmt.Errorf("Find current data offset failed: %v", err)
+		return 0, fmt.Errorf("find current data offset failed: %w", err)
 	}
-	defer data.Seek(origOffset, io.SeekStart)
+	defer params.File.Seek(origOffset, io.SeekStart)
 
 	// Move to the first block that contains target data.
-	if _, err := data.Seek(firstDataBlock*layout.blockSize, io.SeekStart); err != nil {
-		return 0, fmt.Errorf("Seek to datablock start failed: %v", err)
+	if _, err := params.File.Seek(firstDataBlock*layout.blockSize, io.SeekStart); err != nil {
+		return 0, fmt.Errorf("seek to datablock start failed: %w", err)
 	}
 
 	buf := make([]byte, layout.blockSize)
@@ -255,7 +376,7 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
 	for i := firstDataBlock; i <= lastDataBlock; i++ {
 		// Read a block that includes all or part of target range in
 		// input data.
-		bytesRead, err := data.Read(buf)
+		bytesRead, err := params.File.Read(buf)
 		readErr = err
 		// If at the end of input data and all previous blocks are
 		// verified, return the verified input data and EOF.
@@ -263,7 +384,7 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
 			break
 		}
 		if readErr != nil && readErr != io.EOF {
-			return 0, fmt.Errorf("Read from data failed: %v", err)
+			return 0, fmt.Errorf("read from data failed: %w", err)
 		}
 		// If this is the end of file, zero the remaining bytes in buf,
 		// otherwise they are still from the previous block.
@@ -274,22 +395,29 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
 				buf[j] = 0
 			}
 		}
-		if err := verifyBlock(tree, layout, buf, i, expectedRoot); err != nil {
+		descriptor := VerityDescriptor{
+			Name: params.Name,
+			Mode: params.Mode,
+			UID:  params.UID,
+			GID:  params.GID,
+		}
+		if err := verifyBlock(params.Tree, descriptor, layout, buf, i, params.ExpectedRoot); err != nil {
 			return 0, err
 		}
+
 		// startOff is the beginning of the read range within the
 		// current data block. Note that for all blocks other than the
 		// first, startOff should be 0.
 		startOff := int64(0)
 		if i == firstDataBlock {
-			startOff = readOffset % layout.blockSize
+			startOff = params.ReadOffset % layout.blockSize
 		}
 		// endOff is the end of the read range within the current data
 		// block. Note that for all blocks other than the last,  endOff
 		// should be the block size.
 		endOff := layout.blockSize
 		if i == lastDataBlock {
-			endOff = (readOffset+readSize-1)%layout.blockSize + 1
+			endOff = (params.ReadOffset+params.ReadSize-1)%layout.blockSize + 1
 		}
 		// If the provided size exceeds the end of input data, we should
 		// only copy the parts in buf that's part of input data.
@@ -299,7 +427,7 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
 		if endOff > int64(bytesRead) {
 			endOff = int64(bytesRead)
 		}
-		n, err := w.Write(buf[startOff:endOff])
+		n, err := params.Out.Write(buf[startOff:endOff])
 		if err != nil {
 			return total, err
 		}
@@ -313,9 +441,11 @@ func Verify(w io.Writer, data, tree io.ReadSeeker, dataSize int64, readOffset in
 // original data. The block is verified through each level of the tree. It
 // fails if the calculated hash from block is different from any level of
 // hashes stored in tree. And the final root hash is compared with
-// expectedRoot.  verifyBlock modifies the cursor for tree. Users needs to
-// maintain the cursor if intended.
-func verifyBlock(tree io.ReadSeeker, layout Layout, dataBlock []byte, blockIndex int64, expectedRoot []byte) error {
+// expectedRoot.
+//
+// verifyBlock modifies the cursor for tree. Users needs to maintain the cursor
+// if intended.
+func verifyBlock(tree io.ReadSeeker, descriptor VerityDescriptor, layout Layout, dataBlock []byte, blockIndex int64, expectedRoot []byte) error {
 	if len(dataBlock) != int(layout.blockSize) {
 		return fmt.Errorf("incorrect block size")
 	}
@@ -352,21 +482,13 @@ func verifyBlock(tree io.ReadSeeker, layout Layout, dataBlock []byte, blockIndex
 		}
 
 		if !bytes.Equal(digest, expectedDigest) {
-			return fmt.Errorf("Verification failed")
-		}
-
-		// If this is the root layer, no need to generate next level
-		// hash.
-		if level == layout.rootLevel() {
-			break
+			return fmt.Errorf("verification failed")
 		}
 		blockIndex = blockIndex / layout.hashesPerBlock()
 	}
 
-	// Verification for the tree succeeded. Now compare the root hash in the
-	// tree with expectedRoot.
-	if !bytes.Equal(digest[:], expectedRoot) {
-		return fmt.Errorf("Verification failed")
-	}
-	return nil
+	// Verification for the tree succeeded. Now hash the descriptor with
+	// the root hash and compare it with expectedRoot.
+	descriptor.RootHash = digest
+	return verifyDescriptor(descriptor, expectedRoot)
 }
diff --git a/pkg/merkletree/merkletree_test.go b/pkg/merkletree/merkletree_test.go
index daaca759a..bb11ec844 100644
--- a/pkg/merkletree/merkletree_test.go
+++ b/pkg/merkletree/merkletree_test.go
@@ -84,6 +84,13 @@ func TestLayout(t *testing.T) {
 	}
 }
 
+const (
+	defaultName = "merkle_test"
+	defaultMode = 0644
+	defaultUID  = 0
+	defaultGID  = 0
+)
+
 // bytesReadWriter is used to read from/write to/seek in a byte array. Unlike
 // bytes.Buffer, it keeps the whole buffer during read so that it can be reused.
 type bytesReadWriter struct {
@@ -138,19 +145,19 @@ func TestGenerate(t *testing.T) {
 	}{
 		{
 			data:         bytes.Repeat([]byte{0}, usermem.PageSize),
-			expectedRoot: []byte{173, 127, 172, 178, 88, 111, 198, 233, 102, 192, 4, 215, 209, 209, 107, 2, 79, 88, 5, 255, 124, 180, 124, 122, 133, 218, 189, 139, 72, 137, 44, 167},
+			expectedRoot: []byte{64, 253, 58, 72, 192, 131, 82, 184, 193, 33, 108, 142, 43, 46, 179, 134, 244, 21, 29, 190, 14, 39, 66, 129, 6, 46, 200, 211, 30, 247, 191, 252},
 		},
 		{
 			data:         bytes.Repeat([]byte{0}, 128*usermem.PageSize+1),
-			expectedRoot: []byte{62, 93, 40, 92, 161, 241, 30, 223, 202, 99, 39, 2, 132, 113, 240, 139, 117, 99, 79, 243, 54, 18, 100, 184, 141, 121, 238, 46, 149, 202, 203, 132},
+			expectedRoot: []byte{182, 223, 218, 62, 65, 185, 160, 219, 93, 119, 186, 88, 205, 32, 122, 231, 173, 72, 78, 76, 65, 57, 177, 146, 159, 39, 44, 123, 230, 156, 97, 26},
 		},
 		{
 			data:         []byte{'a'},
-			expectedRoot: []byte{52, 75, 204, 142, 172, 129, 37, 14, 145, 137, 103, 203, 11, 162, 209, 205, 30, 169, 213, 72, 20, 28, 243, 24, 242, 2, 92, 43, 169, 59, 110, 210},
+			expectedRoot: []byte{28, 201, 8, 36, 150, 178, 111, 5, 193, 212, 129, 205, 206, 124, 211, 90, 224, 142, 81, 183, 72, 165, 243, 240, 242, 241, 76, 127, 101, 61, 63, 11},
 		},
 		{
 			data:         bytes.Repeat([]byte{'a'}, usermem.PageSize),
-			expectedRoot: []byte{201, 62, 238, 45, 13, 176, 47, 16, 172, 199, 70, 13, 149, 118, 225, 34, 220, 248, 205, 83, 196, 191, 141, 252, 174, 27, 62, 116, 235, 207, 255, 90},
+			expectedRoot: []byte{106, 58, 160, 152, 41, 68, 38, 108, 245, 74, 177, 84, 64, 193, 19, 176, 249, 86, 27, 193, 85, 164, 99, 240, 79, 104, 148, 222, 76, 46, 191, 79},
 		},
 	}
 
@@ -158,16 +165,25 @@ func TestGenerate(t *testing.T) {
 		t.Run(fmt.Sprintf("%d:%v", len(tc.data), tc.data[0]), func(t *testing.T) {
 			for _, dataAndTreeInSameFile := range []bool{false, true} {
 				var tree bytesReadWriter
-				var root []byte
-				var err error
+				params := GenerateParams{
+					Size:                  int64(len(tc.data)),
+					Name:                  defaultName,
+					Mode:                  defaultMode,
+					UID:                   defaultUID,
+					GID:                   defaultGID,
+					TreeReader:            &tree,
+					TreeWriter:            &tree,
+					DataAndTreeInSameFile: dataAndTreeInSameFile,
+				}
 				if dataAndTreeInSameFile {
 					tree.Write(tc.data)
-					root, err = Generate(&tree, int64(len(tc.data)), &tree, &tree, dataAndTreeInSameFile)
+					params.File = &tree
 				} else {
-					root, err = Generate(&bytesReadWriter{
+					params.File = &bytesReadWriter{
 						bytes: tc.data,
-					}, int64(len(tc.data)), &tree, &tree, dataAndTreeInSameFile)
+					}
 				}
+				root, err := Generate(&params)
 				if err != nil {
 					t.Fatalf("Got err: %v, want nil", err)
 				}
@@ -194,6 +210,10 @@ func TestVerify(t *testing.T) {
 		// modified byte falls in verification range, Verify should
 		// fail, otherwise Verify should still succeed.
 		modifyByte    int64
+		modifyName    bool
+		modifyMode    bool
+		modifyUID     bool
+		modifyGID     bool
 		shouldSucceed bool
 	}{
 		// Verify range start outside the data range should fail.
@@ -222,12 +242,48 @@ func TestVerify(t *testing.T) {
 			modifyByte:    0,
 			shouldSucceed: false,
 		},
-		// Invalid verify range (0 size) should fail.
+		// 0 verify size should only verify metadata.
+		{
+			dataSize:      usermem.PageSize,
+			verifyStart:   0,
+			verifySize:    0,
+			modifyByte:    0,
+			shouldSucceed: true,
+		},
+		// Modified name should fail verification.
+		{
+			dataSize:      usermem.PageSize,
+			verifyStart:   0,
+			verifySize:    0,
+			modifyByte:    0,
+			modifyName:    true,
+			shouldSucceed: false,
+		},
+		// Modified mode should fail verification.
 		{
 			dataSize:      usermem.PageSize,
 			verifyStart:   0,
 			verifySize:    0,
 			modifyByte:    0,
+			modifyMode:    true,
+			shouldSucceed: false,
+		},
+		// Modified UID should fail verification.
+		{
+			dataSize:      usermem.PageSize,
+			verifyStart:   0,
+			verifySize:    0,
+			modifyByte:    0,
+			modifyUID:     true,
+			shouldSucceed: false,
+		},
+		// Modified GID should fail verification.
+		{
+			dataSize:      usermem.PageSize,
+			verifyStart:   0,
+			verifySize:    0,
+			modifyByte:    0,
+			modifyGID:     true,
 			shouldSucceed: false,
 		},
 		// The test cases below use a block-aligned verify range.
@@ -316,16 +372,25 @@ func TestVerify(t *testing.T) {
 
 			for _, dataAndTreeInSameFile := range []bool{false, true} {
 				var tree bytesReadWriter
-				var root []byte
-				var err error
+				genParams := GenerateParams{
+					Size:                  int64(len(data)),
+					Name:                  defaultName,
+					Mode:                  defaultMode,
+					UID:                   defaultUID,
+					GID:                   defaultGID,
+					TreeReader:            &tree,
+					TreeWriter:            &tree,
+					DataAndTreeInSameFile: dataAndTreeInSameFile,
+				}
 				if dataAndTreeInSameFile {
 					tree.Write(data)
-					root, err = Generate(&tree, int64(len(data)), &tree, &tree, dataAndTreeInSameFile)
+					genParams.File = &tree
 				} else {
-					root, err = Generate(&bytesReadWriter{
+					genParams.File = &bytesReadWriter{
 						bytes: data,
-					}, int64(tc.dataSize), &tree, &tree, false /* dataAndTreeInSameFile */)
+					}
 				}
+				root, err := Generate(&genParams)
 				if err != nil {
 					t.Fatalf("Generate failed: %v", err)
 				}
@@ -333,8 +398,34 @@ func TestVerify(t *testing.T) {
 				// Flip a bit in data and checks Verify results.
 				var buf bytes.Buffer
 				data[tc.modifyByte] ^= 1
+				verifyParams := VerifyParams{
+					Out:                   &buf,
+					File:                  bytes.NewReader(data),
+					Tree:                  &tree,
+					Size:                  tc.dataSize,
+					Name:                  defaultName,
+					Mode:                  defaultMode,
+					UID:                   defaultUID,
+					GID:                   defaultGID,
+					ReadOffset:            tc.verifyStart,
+					ReadSize:              tc.verifySize,
+					ExpectedRoot:          root,
+					DataAndTreeInSameFile: dataAndTreeInSameFile,
+				}
+				if tc.modifyName {
+					verifyParams.Name = defaultName + "abc"
+				}
+				if tc.modifyMode {
+					verifyParams.Mode = defaultMode + 1
+				}
+				if tc.modifyUID {
+					verifyParams.UID = defaultUID + 1
+				}
+				if tc.modifyGID {
+					verifyParams.GID = defaultGID + 1
+				}
 				if tc.shouldSucceed {
-					n, err := Verify(&buf, bytes.NewReader(data), &tree, tc.dataSize, tc.verifyStart, tc.verifySize, root, dataAndTreeInSameFile)
+					n, err := Verify(&verifyParams)
 					if err != nil && err != io.EOF {
 						t.Errorf("Verification failed when expected to succeed: %v", err)
 					}
@@ -348,7 +439,7 @@ func TestVerify(t *testing.T) {
 						t.Errorf("Incorrect output buf from Verify")
 					}
 				} else {
-					if _, err := Verify(&buf, bytes.NewReader(data), &tree, tc.dataSize, tc.verifyStart, tc.verifySize, root, dataAndTreeInSameFile); err == nil {
+					if _, err := Verify(&verifyParams); err == nil {
 						t.Errorf("Verification succeeded when expected to fail")
 					}
 				}
@@ -368,16 +459,26 @@ func TestVerifyRandom(t *testing.T) {
 
 	for _, dataAndTreeInSameFile := range []bool{false, true} {
 		var tree bytesReadWriter
-		var root []byte
-		var err error
+		genParams := GenerateParams{
+			Size:                  int64(len(data)),
+			Name:                  defaultName,
+			Mode:                  defaultMode,
+			UID:                   defaultUID,
+			GID:                   defaultGID,
+			TreeReader:            &tree,
+			TreeWriter:            &tree,
+			DataAndTreeInSameFile: dataAndTreeInSameFile,
+		}
+
 		if dataAndTreeInSameFile {
 			tree.Write(data)
-			root, err = Generate(&tree, int64(len(data)), &tree, &tree, dataAndTreeInSameFile)
+			genParams.File = &tree
 		} else {
-			root, err = Generate(&bytesReadWriter{
+			genParams.File = &bytesReadWriter{
 				bytes: data,
-			}, int64(dataSize), &tree, &tree, dataAndTreeInSameFile)
+			}
 		}
+		root, err := Generate(&genParams)
 		if err != nil {
 			t.Fatalf("Generate failed: %v", err)
 		}
@@ -387,9 +488,24 @@ func TestVerifyRandom(t *testing.T) {
 		size := rand.Int63n(dataSize) + 1
 
 		var buf bytes.Buffer
+		verifyParams := VerifyParams{
+			Out:                   &buf,
+			File:                  bytes.NewReader(data),
+			Tree:                  &tree,
+			Size:                  dataSize,
+			Name:                  defaultName,
+			Mode:                  defaultMode,
+			UID:                   defaultUID,
+			GID:                   defaultGID,
+			ReadOffset:            start,
+			ReadSize:              size,
+			ExpectedRoot:          root,
+			DataAndTreeInSameFile: dataAndTreeInSameFile,
+		}
+
 		// Checks that the random portion of data from the original data is
 		// verified successfully.
-		n, err := Verify(&buf, bytes.NewReader(data), &tree, dataSize, start, size, root, dataAndTreeInSameFile)
+		n, err := Verify(&verifyParams)
 		if err != nil && err != io.EOF {
 			t.Errorf("Verification failed for correct data: %v", err)
 		}
@@ -406,13 +522,22 @@ func TestVerifyRandom(t *testing.T) {
 			t.Errorf("Incorrect output buf from Verify")
 		}
 
+		// Verify that modified metadata should fail verification.
 		buf.Reset()
+		verifyParams.Name = defaultName + "abc"
+		if _, err := Verify(&verifyParams); err == nil {
+			t.Error("Verify succeeded for modified metadata, expect failure")
+		}
+
 		// Flip a random bit in randPortion, and check that verification fails.
+		buf.Reset()
 		randBytePos := rand.Int63n(size)
 		data[start+randBytePos] ^= 1
+		verifyParams.File = bytes.NewReader(data)
+		verifyParams.Name = defaultName
 
-		if _, err := Verify(&buf, bytes.NewReader(data), &tree, dataSize, start, size, root, dataAndTreeInSameFile); err == nil {
-			t.Errorf("Verification succeeded for modified data")
+		if _, err := Verify(&verifyParams); err == nil {
+			t.Error("Verification succeeded for modified data, expect failure")
 		}
 	}
 }