diff --git a/metropolis/node/build/mkverity/BUILD.bazel b/metropolis/node/build/mkverity/BUILD.bazel
index d749762..8d67da3 100644
--- a/metropolis/node/build/mkverity/BUILD.bazel
+++ b/metropolis/node/build/mkverity/BUILD.bazel
@@ -1,14 +1,15 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
 
-go_library(
-    name = "go_default_library",
-    srcs = ["main.go"],
-    importpath = "source.monogon.dev/metropolis/node/build/mkverity",
-    visibility = ["//visibility:private"],
-)
-
 go_binary(
     name = "mkverity",
     embed = [":go_default_library"],
     visibility = ["//visibility:private"],
 )
+
+go_library(
+    name = "go_default_library",
+    srcs = ["mkverity.go"],
+    importpath = "source.monogon.dev/metropolis/node/build/mkverity",
+    visibility = ["//visibility:private"],
+    deps = ["//metropolis/pkg/verity:go_default_library"],
+)
diff --git a/metropolis/node/build/mkverity/main.go b/metropolis/node/build/mkverity/main.go
deleted file mode 100644
index d31e647..0000000
--- a/metropolis/node/build/mkverity/main.go
+++ /dev/null
@@ -1,390 +0,0 @@
-// Copyright 2020 The Monogon Project Authors.
-//
-// SPDX-License-Identifier: Apache-2.0
-//
-// 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.
-
-// This package implements a subset of the veritysetup tool from cryptsetup,
-// which is a userland tool to interact with dm-verity devices/images. It was
-// rewritten to provide the minimum of functionality needed for Metropolis
-// without having to package, link against and maintain the original C
-// veritysetup tool.
-//
-// dm-verity is a Linux device mapper target that allows integrity verification of
-// a read-only block device. The block device whose integrity should be checked
-// (the 'data device') must be first processed by a tool like veritysetup (or this
-// tool, mkverity) to generate a hash device and root hash.
-// The original data device, hash device and root hash are then set up as a device
-// mapper target, and any read performed from the data device through the verity
-// target will be verified for integrity by Linux using the hash device and root
-// hash.
-//
-// Internally, the hash device is a Merkle tree of all the bytes in the data
-// device, layed out as layers of 'hash blocks'. Starting with data bytes, layers
-// are built recursively, with each layer's output hash blocks becoming the next
-// layer's data input, ending with the single root hash.
-//
-// For more information about the internals, see the Linux and cryptsetup
-// upstream code:
-//
-// https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity#verity-superblock-format
-package main
-
-import (
-	"bytes"
-	"crypto/rand"
-	"crypto/sha256"
-	"encoding/binary"
-	"fmt"
-	"io"
-	"log"
-	"os"
-)
-
-// veritySuperblock represents data layout inside of a dm-verity hash block
-// device superblock. It follows a preexisting verity implementation:
-//
-// https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity#verity-superblock-format
-type veritySuperblock struct {
-	// signature is the magic signature of a verity hash device superblock,
-	// "verity\0\0".
-	signature [8]uint8
-	// version specifies a superblock format. This structure describes version
-	// '1'.
-	version uint32
-	// hashType defaults to '1' outside Chrome OS, according to scarce dm-verity
-	// documentation.
-	hashType uint32
-	// uuid contains a UUID of the hash device.
-	uuid [16]uint8
-	// algorithm stores an ASCII-encoded name of the hash function used.
-	algorithm [32]uint8
-
-	// dataBlockSize specifies a size of a single data device block, in bytes.
-	dataBlockSize uint32
-	// hashBlockSize specifies a size of a single hash device block, in bytes.
-	hashBlockSize uint32
-	// dataBlocks contains a count of blocks available on the data device.
-	dataBlocks uint64
-
-	// saltSize encodes the size of hash block salt, up to the maximum of 256 bytes.
-	saltSize uint16
-
-	// _pad1 is a zeroed space prepending the salt; unused.
-	_pad1 [6]uint8
-	// exactly saltSize bytes of salt are prepended to data blocks before hashing.
-	salt [256]uint8
-	// _pad2 is a zeroed space after the salt; unused.
-	_pad2 [168]uint8
-}
-
-// divideAndRoundup performs an integer division and returns a rounded up
-// result. Useful in calculating block counts.
-func divideAndRoundup(a, b uint64) uint64 {
-	r := a / b
-	if a%b != 0 {
-		r++
-	}
-	return r
-}
-
-// newSuperblock builds a dm-verity hash device superblock based on the size
-// of data image file reachable through dataImagePath.
-// It returns either a fully initialized veritySuperblock, or an
-// initialization error.
-func newSuperblock(dataImagePath string) (*veritySuperblock, error) {
-	// This implementation only handles SHA256-based verity hash images
-	// with a specific 4096-byte block size.
-	// Block sizes can be updated by adjusting the struct literal below.
-	// A change of a hashing algorithm would require a refactor of
-	// saltedDigest, and references to sha256.Size.
-	//
-	// Fill in the defaults (compare with veritySuperblock definition).
-	sb := veritySuperblock{
-		signature:     [8]uint8{'v', 'e', 'r', 'i', 't', 'y', 0, 0},
-		version:       1,
-		hashType:      1,
-		algorithm:     [32]uint8{'s', 'h', 'a', '2', '5', '6'},
-		saltSize:      256,
-		dataBlockSize: 4096,
-		hashBlockSize: 4096,
-	}
-
-	// Get the data image size and compute the data block count.
-	ds, err := os.Stat(dataImagePath)
-	if err != nil {
-		return nil, fmt.Errorf("while stat-ing data device: %w", err)
-	}
-	if !ds.Mode().IsRegular() {
-		return nil, fmt.Errorf("this program only accepts regular files")
-	}
-	sb.dataBlocks = divideAndRoundup(uint64(ds.Size()), uint64(sb.dataBlockSize))
-
-	// Fill in the superblock UUID and cryptographic salt.
-	if _, err := rand.Read(sb.uuid[:]); err != nil {
-		return nil, fmt.Errorf("when generating UUID: %w", err)
-	}
-	if _, err := rand.Read(sb.salt[:]); err != nil {
-		return nil, fmt.Errorf("when generating salt: %w", err)
-	}
-
-	return &sb, nil
-}
-
-// saltedDigest computes and returns a SHA256 sum of a block prepended
-// with a Superblock-defined salt.
-func (sb *veritySuperblock) saltedDigest(data []byte) (digest [sha256.Size]byte) {
-	h := sha256.New()
-	h.Write(sb.salt[:int(sb.saltSize)])
-	h.Write(data)
-	copy(digest[:], h.Sum(nil))
-	return
-}
-
-// dataBlocksPerHashBlock returns the count of hash operation outputs that
-// fit in a hash device block. This is also the amount of data device
-// blocks it takes to populate a hash device block.
-func (sb *veritySuperblock) dataBlocksPerHashBlock() uint64 {
-	return uint64(sb.hashBlockSize) / sha256.Size
-}
-
-// computeHashBlock reads at most sb.dataBlocksPerHashBlock blocks from
-// the given reader object, returning a padded hash block of length
-// defined by sb.hashBlockSize, and an error, if encountered.
-// In case a non-nil block is returned, it's guaranteed to contain at
-// least one hash. An io.EOF signals that there is no more to be read
-// from 'r'.
-func (sb *veritySuperblock) computeHashBlock(r io.Reader) ([]byte, error) {
-	// Preallocate a whole hash block.
-	hblk := bytes.NewBuffer(make([]byte, 0, sb.hashBlockSize))
-
-	// For every data block, compute a hash and place it in hblk. Continue
-	// till EOF.
-	for b := uint64(0); b < sb.dataBlocksPerHashBlock(); b++ {
-		dbuf := make([]byte, sb.dataBlockSize)
-		// Attempt to read enough data blocks to make a complete hash block.
-		n, err := io.ReadFull(r, dbuf)
-		// If any data was read, make a hash and add it to the hash buffer.
-		if n != 0 {
-			hash := sb.saltedDigest(dbuf)
-			hblk.Write(hash[:])
-		}
-		// Handle the read errors.
-		switch err {
-		case nil:
-		case io.ErrUnexpectedEOF, io.EOF:
-			// io.ReadFull returns io.ErrUnexpectedEOF after a partial read,
-			// and io.EOF if no bytes were read. In both cases it's possible
-			// to end up with a partially filled hash block.
-			if hblk.Len() != 0 {
-				// Return a zero-padded hash block if any hashes were written
-				// to it, and signal that no more blocks can be built.
-				res := hblk.Bytes()
-				return res[:cap(res)], io.EOF
-			}
-			// Return nil if the block doesn't contain any hashes.
-			return nil, io.EOF
-		default:
-			// Wrap unhandled read errors.
-			return nil, fmt.Errorf("while computing a hash block: %w", err)
-		}
-	}
-	// Return a completely filled hash block.
-	res := hblk.Bytes()
-	return res[:cap(res)], nil
-}
-
-// writeSuperblock writes a verity superblock to a given writer object.
-// It returns a write error, if encountered.
-func (sb *veritySuperblock) writeSuperblock(w io.Writer) error {
-	// Write the superblock.
-	if err := binary.Write(w, binary.LittleEndian, sb); err != nil {
-		return fmt.Errorf("while writing a header: %w", err)
-	}
-
-	// Get the padding size by substracting current offset from a hash block
-	// size.
-	co := binary.Size(sb)
-	pbc := int(sb.hashBlockSize) - co
-	if pbc <= 0 {
-		return fmt.Errorf("hash device block size smaller than dm-verity superblock")
-	}
-
-	// Write the padding bytes at the end of the block.
-	if _, err := w.Write(bytes.Repeat([]byte{0}, pbc)); err != nil {
-		return fmt.Errorf("while writing padding: %w", err)
-	}
-	return nil
-}
-
-// computeLevelZero produces the base level of a hash tree. It's the only
-// level calculated based on raw input from the data image.
-// It returns a byte slice containing one or more hash blocks, depending
-// on sb.dataBlocks and sb.hashBlockSize, or an error. The returned slice
-// length is guaranteed to be a multiple of sb.hashBlockSize if no error
-// is returned.
-// BUG(mz): Current implementation requires a 1/128th of the data image
-// size to be allocatable on the heap.
-func (sb *veritySuperblock) computeLevel(r io.Reader) ([]byte, error) {
-	// hbuf will store all the computed hash blocks.
-	var hbuf bytes.Buffer
-	// Compute one or more hash blocks, reading all data available in the
-	// 'r' reader object, and write them into hbuf.
-	for {
-		hblk, err := sb.computeHashBlock(r)
-		if err != nil && err != io.EOF {
-			return nil, fmt.Errorf("while building a hash tree level: %w", err)
-		}
-		if hblk != nil {
-			_, err := hbuf.Write(hblk)
-			if err != nil {
-				return nil, fmt.Errorf("while writing to hash block buffer: %w", err)
-			}
-		}
-		if err == io.EOF {
-			break
-		}
-	}
-	return hbuf.Bytes(), nil
-}
-
-// computeHashTree builds a complete hash tree based on the given reader
-// object. Levels are appended to resulting hashTree from bottom to top.
-// It returns a verity hash tree, a verity root hash, and an error, if
-// encountered.
-func (sb *veritySuperblock) computeHashTree(r io.Reader) ([][]byte, []byte, error) {
-	// First, hash contents of the data image. This will result in a bottom
-	// level of the hash tree.
-	var hashTree [][]byte
-	lz, err := sb.computeLevel(r)
-	if err != nil {
-		return nil, nil, fmt.Errorf("while computing the base level: %w", err)
-	}
-	hashTree = append(hashTree, lz)
-
-	// Other levels are built by hashing the hash blocks comprising a level
-	// below.
-	for {
-		// Create the next level by hashing the previous one.
-		pl := hashTree[len(hashTree)-1]
-		nl, err := sb.computeLevel(bytes.NewReader(pl))
-		if err != nil {
-			return nil, nil, fmt.Errorf("while computing a level: %w", err)
-		}
-		// Append the resulting next level to a tree.
-		hashTree = append(hashTree, nl)
-
-		if len(nl) == int(sb.hashBlockSize) {
-			// The last level to compute has a size of exactly one hash block.
-			// That's the root level. Its hash serves as a cryptographic root of
-			// trust and is returned separately.
-			rootHash := sb.saltedDigest(nl)
-			return hashTree, rootHash[:], nil
-		}
-	}
-}
-
-// writeHashTree writes a verity-formatted hash tree to the given writer
-// object. Compare with computeHashTree.
-// It returns the count of bytes written and a write error, if encountered.
-func (sb *veritySuperblock) writeHashTree(w io.Writer, treeLevels [][]byte) error {
-	// Write the hash tree levels from top to bottom.
-	for l := len(treeLevels) - 1; l >= 0; l-- {
-		level := treeLevels[l]
-		// Call w.Write until a whole level is written.
-		for len(level) != 0 {
-			n, err := w.Write(level)
-			if err != nil && err != io.ErrShortWrite {
-				return fmt.Errorf("while writing a level: %w", err)
-			}
-			level = level[n:]
-		}
-	}
-	return nil
-}
-
-// createHashImage creates a complete dm-verity hash image at
-// hashImagePath. Contents of the file at dataImagePath are accessed
-// read-only, hashed and written to the hash image in the process.
-// It returns a verity root hash and an error, if encountered.
-func createHashImage(dataImagePath, hashImagePath string) ([]byte, error) {
-	// Inspect the data image and build a verity superblock based on its size.
-	sb, err := newSuperblock(dataImagePath)
-	if err != nil {
-		return nil, fmt.Errorf("while building a superblock: %w", err)
-	}
-
-	// Open the data image for reading.
-	dataImage, err := os.Open(dataImagePath)
-	if err != nil {
-		return nil, fmt.Errorf("while opening the data image: %w", err)
-	}
-	defer dataImage.Close()
-
-	// Create an empty hash image file.
-	hashImage, err := os.OpenFile(hashImagePath, os.O_RDWR|os.O_CREATE, 0644)
-	if err != nil {
-		return nil, fmt.Errorf("while opening the hash image for writing: %w", err)
-	}
-	defer hashImage.Close()
-
-	// Write the superblock to the hash image.
-	if err = sb.writeSuperblock(hashImage); err != nil {
-		return nil, fmt.Errorf("while writing the superblock: %w", err)
-	}
-
-	// Compute a verity hash tree by hashing contents of the data image. Then,
-	// write it to the hash image.
-	treeLevels, rootHash, err := sb.computeHashTree(dataImage)
-	if err != nil {
-		return nil, fmt.Errorf("while building a hash tree: %w", err)
-	}
-	if err = sb.writeHashTree(hashImage, treeLevels); err != nil {
-		return nil, fmt.Errorf("while writing a hash tree: %w", err)
-	}
-
-	// Return a verity root hash, serving as a root of trust.
-	return rootHash, nil
-}
-
-// usage prints program usage information.
-func usage(executable string) {
-	fmt.Println("Usage: ", executable, " format <data image> <hash image>")
-}
-
-func main() {
-	// Process the command line arguments maintaining a partial
-	// compatibility with veritysetup.
-	if len(os.Args) != 4 {
-		usage(os.Args[0])
-		os.Exit(2)
-	}
-	command := os.Args[1]
-	dataImagePath := os.Args[2]
-	hashImagePath := os.Args[3]
-
-	switch command {
-	case "format":
-		rootHash, err := createHashImage(dataImagePath, hashImagePath)
-		if err != nil {
-			log.Fatal(err)
-		}
-		// The output differs from the original veritysetup utility in that hash
-		// isn't prepended by "Root hash: " string. It's left this way to
-		// facilitate machine processing.
-		fmt.Printf("%x", rootHash)
-	default:
-		usage(os.Args[0])
-		os.Exit(2)
-	}
-}
diff --git a/metropolis/node/build/mkverity/mkverity.go b/metropolis/node/build/mkverity/mkverity.go
new file mode 100644
index 0000000..272bc73
--- /dev/null
+++ b/metropolis/node/build/mkverity/mkverity.go
@@ -0,0 +1,101 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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.
+
+// This package implements a command line tool that creates dm-verity hash
+// images at a selected path, given an existing data image. The tool
+// outputs a Verity mapping table on success.
+//
+// For more information, see:
+// - source.monogon.dev/metropolis/pkg/verity
+// - https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity
+package main
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"os"
+
+	"source.monogon.dev/metropolis/pkg/verity"
+)
+
+// createHashImage creates a complete dm-verity hash image at
+// hashImagePath. Contents of the file at dataImagePath are accessed
+// read-only, hashed and written to the hash image in the process.
+// The verity superblock is written only if wsb is true.
+// It returns a string-convertible VerityMappingTable, or an error.
+func createHashImage(dataImagePath, hashImagePath string, wsb bool) (*verity.MappingTable, error) {
+	// Open the data image for reading.
+	dataImage, err := os.Open(dataImagePath)
+	if err != nil {
+		return nil, fmt.Errorf("while opening the data image: %w", err)
+	}
+	defer dataImage.Close()
+	// Create an empty hash image file.
+	hashImage, err := os.OpenFile(hashImagePath, os.O_RDWR|os.O_CREATE, 0644)
+	if err != nil {
+		return nil, fmt.Errorf("while opening the hash image for writing: %w", err)
+	}
+	defer hashImage.Close()
+
+	// Write hashImage contents. Start with initializing a verity encoder,
+	// seting hashImage as its output.
+	v, err := verity.NewEncoder(hashImage, wsb)
+	if err != nil {
+		return nil, fmt.Errorf("while initializing a verity encoder: %w", err)
+	}
+	// Hash the contents of dataImage, block by block.
+	_, err = io.Copy(v, dataImage)
+	if err != nil {
+		return nil, fmt.Errorf("while reading the data image: %w", err)
+	}
+	// The resulting hash tree won't be written until Close is called.
+	err = v.Close()
+	if err != nil {
+		return nil, fmt.Errorf("while writing the hash image: %w", err)
+	}
+
+	// Return an encoder-generated verity mapping table, containing the salt
+	// and the root hash.
+	mt, err := v.MappingTable(dataImagePath, hashImagePath)
+	if err != nil {
+		return nil, fmt.Errorf("while querying for the mapping table: %w", err)
+	}
+	return mt, nil
+}
+
+// usage prints program usage information.
+func usage(executable string) {
+	fmt.Println("Usage: ", executable, " <data image> <hash image>")
+}
+
+func main() {
+	if len(os.Args) != 3 {
+		usage(os.Args[0])
+		os.Exit(2)
+	}
+	dataImagePath := os.Args[1]
+	hashImagePath := os.Args[2]
+
+	// Attempt to build a new Verity hash Image at hashImagePath, based on
+	// the data image at dataImagePath. Include the Verity superblock.
+	mt, err := createHashImage(dataImagePath, hashImagePath, true)
+	if err != nil {
+		log.Fatal(err)
+	}
+	// Print a Device Mapper compatible mapping table.
+	fmt.Println(mt)
+}