From 76386afe5ddd642058c5bade80b682aee9ef47e9 Mon Sep 17 00:00:00 2001
From: Asra Ali <asraa@google.com>
Date: Fri, 16 Sep 2022 11:06:31 -0500
Subject: [PATCH 1/4] feat: pass logger into repo and client

Signed-off-by: Asra Ali <asraa@google.com>
---
 client/client.go                       | 27 +++++++++++---
 client/delegations.go                  |  3 +-
 pkg/deprecated/deprecated_repo_test.go | 11 +++++-
 pkg/keys/deprecated_ecdsa.go           | 28 ++++++++++++---
 pkg/keys/deprecated_ecdsa_test.go      | 21 +++++++++++
 pkg/keys/ecdsa.go                      |  2 +-
 pkg/keys/ed25519.go                    |  2 +-
 pkg/keys/keys.go                       | 13 +++++--
 pkg/keys/rsa.go                        |  2 +-
 repo.go                                | 50 +++++++++++++++++++++++---
 verify/db.go                           | 34 +++++++++++++-----
 11 files changed, 165 insertions(+), 28 deletions(-)

diff --git a/client/client.go b/client/client.go
index 17ddc980..8e226905 100644
--- a/client/client.go
+++ b/client/client.go
@@ -5,6 +5,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"io"
+	"log"
 
 	"github.com/theupdateframework/go-tuf/data"
 	"github.com/theupdateframework/go-tuf/util"
@@ -88,6 +89,10 @@ type Client struct {
 	// consistent snapshots (as specified in root.json)
 	consistentSnapshot bool
 
+	// this is an optional log writer.
+	// if nil, uses io.Discard
+	logger *log.Logger
+
 	// MaxDelegations limits by default the number of delegations visited for any
 	// target
 	MaxDelegations int
@@ -96,13 +101,26 @@ type Client struct {
 	MaxRootRotations int
 }
 
-func NewClient(local LocalStore, remote RemoteStore) *Client {
-	return &Client{
+type ClientOpts func(c *Client)
+
+func WithLogger(logger *log.Logger) ClientOpts {
+	return func(c *Client) {
+		c.logger = logger
+	}
+}
+
+func NewClient(local LocalStore, remote RemoteStore, opts ...ClientOpts) *Client {
+	client := &Client{
 		local:            local,
 		remote:           remote,
 		MaxDelegations:   defaultMaxDelegations,
 		MaxRootRotations: defaultMaxRootRotations,
+		logger:           log.New(io.Discard, "", 0),
+	}
+	for _, opt := range opts {
+		opt(client)
 	}
+	return client
 }
 
 // Init initializes a local repository from root metadata.
@@ -452,7 +470,8 @@ func (c *Client) loadAndVerifyRootMeta(rootJSON []byte, ignoreExpiredCheck bool)
 	if err := json.Unmarshal(s.Signed, root); err != nil {
 		return err
 	}
-	ndb := verify.NewDB()
+
+	ndb := verify.NewDB(verify.WithLogger(c.logger))
 	for id, k := range root.Keys {
 		if err := ndb.AddKey(id, k); err != nil {
 			return err
@@ -500,7 +519,7 @@ func (c *Client) verifyRoot(aJSON []byte, bJSON []byte) (*data.Root, error) {
 		return nil, err
 	}
 
-	ndb := verify.NewDB()
+	ndb := verify.NewDB(verify.WithLogger(c.logger))
 	for id, k := range aRoot.Keys {
 		if err := ndb.AddKey(id, k); err != nil {
 			return nil, err
diff --git a/client/delegations.go b/client/delegations.go
index de3e6647..773226c7 100644
--- a/client/delegations.go
+++ b/client/delegations.go
@@ -43,7 +43,8 @@ func (c *Client) getTargetFileMeta(target string) (data.TargetFileMeta, error) {
 		}
 
 		if targets.Delegations != nil {
-			delegationsDB, err := verify.NewDBFromDelegations(targets.Delegations)
+			delegationsDB, err := verify.NewDBFromDelegations(targets.Delegations,
+				verify.WithLogger(c.logger))
 			if err != nil {
 				return data.TargetFileMeta{}, err
 			}
diff --git a/pkg/deprecated/deprecated_repo_test.go b/pkg/deprecated/deprecated_repo_test.go
index 6d194ab5..9500219f 100644
--- a/pkg/deprecated/deprecated_repo_test.go
+++ b/pkg/deprecated/deprecated_repo_test.go
@@ -1,11 +1,14 @@
 package deprecated
 
 import (
+	"bytes"
 	"crypto"
 	"crypto/elliptic"
 	"crypto/rand"
 	"crypto/sha256"
 	"encoding/json"
+	"log"
+	"strings"
 	"testing"
 
 	"github.com/secure-systems-lab/go-securesystemslib/cjson"
@@ -34,7 +37,10 @@ func genKey(c *C, r *repo.Repo, role string) []string {
 func (rs *RepoSuite) TestDeprecatedHexEncodedKeysSucceed(c *C) {
 	files := map[string][]byte{"foo.txt": []byte("foo")}
 	local := repo.MemoryStore(make(map[string]json.RawMessage), files)
-	r, err := repo.NewRepo(local)
+	var logBytes bytes.Buffer
+	opts := repo.WithLogger(log.New(&logBytes, "", 0))
+
+	r, err := repo.NewRepoWithOpts(local, opts)
 	c.Assert(err, IsNil)
 
 	r.Init(false)
@@ -79,4 +85,7 @@ func (rs *RepoSuite) TestDeprecatedHexEncodedKeysSucceed(c *C) {
 	c.Assert(r.Snapshot(), IsNil)
 	c.Assert(r.Timestamp(), IsNil)
 	c.Assert(r.Commit(), IsNil)
+
+	// Check logs.
+	c.Assert(strings.Contains(logBytes.String(), keys.WarnDeprecatedEcdsaKey), Equals, true)
 }
diff --git a/pkg/keys/deprecated_ecdsa.go b/pkg/keys/deprecated_ecdsa.go
index 4a8f151e..d12a22bf 100644
--- a/pkg/keys/deprecated_ecdsa.go
+++ b/pkg/keys/deprecated_ecdsa.go
@@ -9,13 +9,25 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"os"
+	"log"
 
 	"github.com/theupdateframework/go-tuf/data"
 )
 
-func NewDeprecatedEcdsaVerifier() Verifier {
-	return &ecdsaVerifierWithDeprecatedSupport{}
+var (
+	WarnDeprecatedEcdsaKey = "tuf: warning using deprecated ecdsa hex-encoded keys"
+)
+
+func NewDeprecatedEcdsaVerifier(opts ...VerifierOpts) Verifier {
+	verifier := &ecdsaVerifierWithDeprecatedSupport{
+		logger: log.New(io.Discard, "", log.LstdFlags),
+	}
+	for _, opt := range opts {
+		if opt.Logger != nil {
+			verifier.logger = opt.Logger
+		}
+	}
+	return verifier
 }
 
 type ecdsaVerifierWithDeprecatedSupport struct {
@@ -23,6 +35,8 @@ type ecdsaVerifierWithDeprecatedSupport struct {
 	// This will switch based on whether this is a PEM-encoded key
 	// or a deprecated hex-encoded key.
 	Verifier
+	// This is used to write the deprecated warning to.
+	logger *log.Logger
 }
 
 func (p *ecdsaVerifierWithDeprecatedSupport) UnmarshalPublicKey(key *data.PublicKey) error {
@@ -30,7 +44,9 @@ func (p *ecdsaVerifierWithDeprecatedSupport) UnmarshalPublicKey(key *data.Public
 	pemVerifier := &EcdsaVerifier{}
 	if err := pemVerifier.UnmarshalPublicKey(key); err != nil {
 		// Try the deprecated hex-encoded verifier
-		hexVerifier := &deprecatedP256Verifier{}
+		hexVerifier := &deprecatedP256Verifier{
+			logger: p.logger,
+		}
 		if err := hexVerifier.UnmarshalPublicKey(key); err != nil {
 			return err
 		}
@@ -51,6 +67,8 @@ func (p *ecdsaVerifierWithDeprecatedSupport) UnmarshalPublicKey(key *data.Public
 type deprecatedP256Verifier struct {
 	PublicKey data.HexBytes `json:"public"`
 	key       *data.PublicKey
+	// This is used to write the deprecated warning to.
+	logger *log.Logger
 }
 
 func (p *deprecatedP256Verifier) Public() string {
@@ -98,6 +116,6 @@ func (p *deprecatedP256Verifier) UnmarshalPublicKey(key *data.PublicKey) error {
 	}
 
 	p.key = key
-	fmt.Fprintln(os.Stderr, "tuf: warning using deprecated ecdsa hex-encoded keys")
+	p.logger.Print(WarnDeprecatedEcdsaKey)
 	return nil
 }
diff --git a/pkg/keys/deprecated_ecdsa_test.go b/pkg/keys/deprecated_ecdsa_test.go
index ddfaa84d..57563b29 100644
--- a/pkg/keys/deprecated_ecdsa_test.go
+++ b/pkg/keys/deprecated_ecdsa_test.go
@@ -1,6 +1,7 @@
 package keys
 
 import (
+	"bytes"
 	"crypto"
 	"crypto/ecdsa"
 	"crypto/elliptic"
@@ -8,6 +9,8 @@ import (
 	"crypto/sha256"
 	"encoding/json"
 	"errors"
+	"log"
+	"strings"
 
 	"github.com/theupdateframework/go-tuf/data"
 	. "gopkg.in/check.v1"
@@ -127,3 +130,21 @@ func (DeprecatedECDSASuite) TestMarshalUnmarshalPublicKey(c *C) {
 
 	c.Assert(deprecatedEcdsa.MarshalPublicKey(), DeepEquals, pub)
 }
+
+func (DeprecatedECDSASuite) TestLogMessageWriter(c *C) {
+	signer, err := generatedDeprecatedSigner()
+	c.Assert(err, IsNil)
+
+	pub := signer.PublicData()
+
+	var logBytes bytes.Buffer
+	opts := WithLogger(log.New(&logBytes, "", 0))
+
+	deprecatedEcdsa := NewDeprecatedEcdsaVerifier(opts)
+	err = deprecatedEcdsa.UnmarshalPublicKey(pub)
+	c.Assert(err, IsNil)
+	c.Assert(strings.TrimSuffix(logBytes.String(), "\n"), Equals,
+		WarnDeprecatedEcdsaKey)
+
+	c.Assert(deprecatedEcdsa.MarshalPublicKey(), DeepEquals, pub)
+}
diff --git a/pkg/keys/ecdsa.go b/pkg/keys/ecdsa.go
index ee93e330..c7083e8a 100644
--- a/pkg/keys/ecdsa.go
+++ b/pkg/keys/ecdsa.go
@@ -24,7 +24,7 @@ func init() {
 	SignerMap.Store(data.KeyTypeECDSA_SHA2_P256, newEcdsaSigner)
 }
 
-func NewEcdsaVerifier() Verifier {
+func NewEcdsaVerifier(_ ...VerifierOpts) Verifier {
 	return &EcdsaVerifier{}
 }
 
diff --git a/pkg/keys/ed25519.go b/pkg/keys/ed25519.go
index 1e4c66cc..f7309b1b 100644
--- a/pkg/keys/ed25519.go
+++ b/pkg/keys/ed25519.go
@@ -23,7 +23,7 @@ func NewEd25519Signer() Signer {
 	return &ed25519Signer{}
 }
 
-func NewEd25519Verifier() Verifier {
+func NewEd25519Verifier(_ ...VerifierOpts) Verifier {
 	return &ed25519Verifier{}
 }
 
diff --git a/pkg/keys/keys.go b/pkg/keys/keys.go
index dc5f3ea2..7ac9c13e 100644
--- a/pkg/keys/keys.go
+++ b/pkg/keys/keys.go
@@ -3,6 +3,7 @@ package keys
 import (
 	"errors"
 	"fmt"
+	"log"
 	"sync"
 
 	"github.com/theupdateframework/go-tuf/data"
@@ -57,12 +58,20 @@ type Signer interface {
 	SignMessage(message []byte) ([]byte, error)
 }
 
-func GetVerifier(key *data.PublicKey) (Verifier, error) {
+type VerifierOpts struct {
+	Logger *log.Logger
+}
+
+func WithLogger(logger *log.Logger) VerifierOpts {
+	return VerifierOpts{logger}
+}
+
+func GetVerifier(key *data.PublicKey, opts ...VerifierOpts) (Verifier, error) {
 	st, ok := VerifierMap.Load(key.Type)
 	if !ok {
 		return nil, ErrInvalidKey
 	}
-	s := st.(func() Verifier)()
+	s := st.(func(opts ...VerifierOpts) Verifier)(opts...)
 	if err := s.UnmarshalPublicKey(key); err != nil {
 		return nil, fmt.Errorf("tuf: error unmarshalling key: %w", err)
 	}
diff --git a/pkg/keys/rsa.go b/pkg/keys/rsa.go
index 618f104e..3fc82cde 100644
--- a/pkg/keys/rsa.go
+++ b/pkg/keys/rsa.go
@@ -21,7 +21,7 @@ func init() {
 	SignerMap.Store(data.KeyTypeRSASSA_PSS_SHA256, newRsaSigner)
 }
 
-func newRsaVerifier() Verifier {
+func newRsaVerifier(_ ...VerifierOpts) Verifier {
 	return &rsaVerifier{}
 }
 
diff --git a/repo.go b/repo.go
index 603785f1..732dee01 100644
--- a/repo.go
+++ b/repo.go
@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"log"
 	"path"
 	"sort"
 	"strings"
@@ -48,18 +49,47 @@ type Repo struct {
 	meta           map[string]json.RawMessage
 	prefix         string
 	indent         string
+	logger         *log.Logger
+}
+
+type RepoOpts func(r *Repo)
+
+func WithLogger(logger *log.Logger) RepoOpts {
+	return func(r *Repo) {
+		r.logger = logger
+	}
+}
+
+func WithHashAlgorithms(hashAlgorithms ...string) RepoOpts {
+	return func(r *Repo) {
+		r.hashAlgorithms = hashAlgorithms
+	}
+}
+
+func WithPrefix(prefix string) RepoOpts {
+	return func(r *Repo) {
+		r.prefix = prefix
+	}
+}
+
+func WithIndex(indent string) RepoOpts {
+	return func(r *Repo) {
+		r.indent = indent
+	}
 }
 
 func NewRepo(local LocalStore, hashAlgorithms ...string) (*Repo, error) {
 	return NewRepoIndent(local, "", "", hashAlgorithms...)
 }
 
-func NewRepoIndent(local LocalStore, prefix string, indent string, hashAlgorithms ...string) (*Repo, error) {
+func NewRepoIndent(local LocalStore, prefix string, indent string,
+	hashAlgorithms ...string) (*Repo, error) {
 	r := &Repo{
 		local:          local,
 		hashAlgorithms: hashAlgorithms,
 		prefix:         prefix,
 		indent:         indent,
+		logger:         log.New(io.Discard, "", 0),
 	}
 
 	var err error
@@ -70,6 +100,17 @@ func NewRepoIndent(local LocalStore, prefix string, indent string, hashAlgorithm
 	return r, nil
 }
 
+func NewRepoWithOpts(local LocalStore, opts ...RepoOpts) (*Repo, error) {
+	r, err := NewRepo(local)
+	if err != nil {
+		return nil, err
+	}
+	for _, opt := range opts {
+		opt(r)
+	}
+	return r, nil
+}
+
 func (r *Repo) Init(consistentSnapshot bool) error {
 	t, err := r.topLevelTargets()
 	if err != nil {
@@ -96,7 +137,7 @@ func (r *Repo) Init(consistentSnapshot bool) error {
 }
 
 func (r *Repo) topLevelKeysDB() (*verify.DB, error) {
-	db := verify.NewDB()
+	db := verify.NewDB(verify.WithLogger(r.logger))
 	root, err := r.root()
 	if err != nil {
 		return nil, err
@@ -934,7 +975,7 @@ func (r *Repo) delegatorDBs(delegateeRole string) ([]*verify.DB, error) {
 			continue
 		}
 
-		db, err := verify.NewDBFromDelegations(t.Delegations)
+		db, err := verify.NewDBFromDelegations(t.Delegations, verify.WithLogger(r.logger))
 		if err != nil {
 			return nil, err
 		}
@@ -983,7 +1024,8 @@ func (r *Repo) targetDelegationForPath(path string, preferredRole string) (*data
 		}
 
 		if targetsMeta.Delegations != nil && len(targetsMeta.Delegations.Roles) > 0 {
-			db, err := verify.NewDBFromDelegations(targetsMeta.Delegations)
+			db, err := verify.NewDBFromDelegations(targetsMeta.Delegations,
+				verify.WithLogger(r.logger))
 			if err != nil {
 				return nil, nil, err
 			}
diff --git a/verify/db.go b/verify/db.go
index 04f5bf1c..acaf7b6e 100644
--- a/verify/db.go
+++ b/verify/db.go
@@ -1,6 +1,9 @@
 package verify
 
 import (
+	"io"
+	"log"
+
 	"github.com/theupdateframework/go-tuf/data"
 	"github.com/theupdateframework/go-tuf/internal/roles"
 	"github.com/theupdateframework/go-tuf/pkg/keys"
@@ -19,22 +22,33 @@ func (r *Role) ValidKey(id string) bool {
 type DB struct {
 	roles     map[string]*Role
 	verifiers map[string]keys.Verifier
+	logger    *log.Logger
+}
+
+type DBOpts func(db *DB)
+
+func WithLogger(logger *log.Logger) DBOpts {
+	return func(db *DB) {
+		db.logger = logger
+	}
 }
 
-func NewDB() *DB {
-	return &DB{
+func NewDB(opts ...DBOpts) *DB {
+	db := &DB{
 		roles:     make(map[string]*Role),
 		verifiers: make(map[string]keys.Verifier),
+		logger:    log.New(io.Discard, "", 0),
+	}
+	for _, opt := range opts {
+		opt(db)
 	}
+	return db
 }
 
 // NewDBFromDelegations returns a DB that verifies delegations
 // of a given Targets.
-func NewDBFromDelegations(d *data.Delegations) (*DB, error) {
-	db := &DB{
-		roles:     make(map[string]*Role, len(d.Roles)),
-		verifiers: make(map[string]keys.Verifier, len(d.Keys)),
-	}
+func NewDBFromDelegations(d *data.Delegations, opts ...DBOpts) (*DB, error) {
+	db := NewDB(opts...)
 	for _, r := range d.Roles {
 		if _, ok := roles.TopLevelRoles[r.Name]; ok {
 			return nil, ErrInvalidDelegatedRole
@@ -53,7 +67,11 @@ func NewDBFromDelegations(d *data.Delegations) (*DB, error) {
 }
 
 func (db *DB) AddKey(id string, k *data.PublicKey) error {
-	verifier, err := keys.GetVerifier(k)
+	opts := make([]keys.VerifierOpts, 0)
+	if db.logger != nil {
+		opts = append(opts, keys.WithLogger(db.logger))
+	}
+	verifier, err := keys.GetVerifier(k, opts...)
 	if err != nil {
 		return err // ErrInvalidKey
 	}

From 89b085e0a7738097435eda3cbfe50bde90f9907d Mon Sep 17 00:00:00 2001
From: Asra Ali <asraa@google.com>
Date: Fri, 16 Sep 2022 11:10:06 -0500
Subject: [PATCH 2/4] remove prints in repo

Signed-off-by: Asra Ali <asraa@google.com>
---
 repo.go | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/repo.go b/repo.go
index 732dee01..cb4fb976 100644
--- a/repo.go
+++ b/repo.go
@@ -132,7 +132,7 @@ func (r *Repo) Init(consistentSnapshot bool) error {
 		return err
 	}
 
-	fmt.Println("Repository initialized")
+	r.logger.Println("Repository initialized")
 	return nil
 }
 
@@ -574,7 +574,7 @@ func (r *Repo) RevokeKeyWithExpires(keyRole, id string, expires time.Time) error
 
 	err = r.setMeta("root.json", root)
 	if err == nil {
-		fmt.Println("Revoked", keyRole, "key with ID", id, "in root metadata")
+		r.logger.Println("Revoked", keyRole, "key with ID", id, "in root metadata")
 	}
 	return err
 }
@@ -824,7 +824,7 @@ func (r *Repo) Sign(roleFilename string) error {
 	r.meta[roleFilename] = b
 	err = r.local.SetMeta(roleFilename, b)
 	if err == nil {
-		fmt.Println("Signed", roleFilename, "with", numKeys, "key(s)")
+		r.logger.Println("Signed", roleFilename, "with", numKeys, "key(s)")
 	}
 	return err
 }
@@ -1265,7 +1265,7 @@ func (r *Repo) removeTargetsWithExpiresFromMeta(metaName string, paths []string,
 		for _, path := range paths {
 			path = util.NormalizeTarget(path)
 			if _, ok := t.Targets[path]; !ok {
-				fmt.Printf("[%v] The following target is not present: %v\n", metaName, path)
+				r.logger.Printf("[%v] The following target is not present: %v\n", metaName, path)
 				continue
 			}
 			removed = true
@@ -1285,17 +1285,17 @@ func (r *Repo) removeTargetsWithExpiresFromMeta(metaName string, paths []string,
 
 	err = r.setMeta(metaName, t)
 	if err == nil {
-		fmt.Printf("[%v] Removed targets:\n", metaName)
+		r.logger.Printf("[%v] Removed targets:\n", metaName)
 		for _, v := range removed_targets {
-			fmt.Println("*", v)
+			r.logger.Println("*", v)
 		}
 		if len(t.Targets) != 0 {
-			fmt.Printf("[%v] Added/staged targets:\n", metaName)
+			r.logger.Printf("[%v] Added/staged targets:\n", metaName)
 			for k := range t.Targets {
-				fmt.Println("*", k)
+				r.logger.Println("*", k)
 			}
 		} else {
-			fmt.Printf("[%v] There are no added/staged targets\n", metaName)
+			r.logger.Printf("[%v] There are no added/staged targets\n", metaName)
 		}
 	}
 	return err
@@ -1349,7 +1349,7 @@ func (r *Repo) SnapshotWithExpires(expires time.Time) error {
 	}
 	err = r.setMeta("snapshot.json", snapshot)
 	if err == nil {
-		fmt.Println("Staged snapshot.json metadata with expiration date:", snapshot.Expires)
+		r.logger.Println("Staged snapshot.json metadata with expiration date:", snapshot.Expires)
 	}
 	return err
 }
@@ -1381,7 +1381,7 @@ func (r *Repo) TimestampWithExpires(expires time.Time) error {
 
 	err = r.setMeta("timestamp.json", timestamp)
 	if err == nil {
-		fmt.Println("Staged timestamp.json metadata with expiration date:", timestamp.Expires)
+		r.logger.Println("Staged timestamp.json metadata with expiration date:", timestamp.Expires)
 	}
 	return err
 }
@@ -1547,7 +1547,7 @@ func (r *Repo) Commit() error {
 
 	err = r.local.Commit(root.ConsistentSnapshot, versions, hashes)
 	if err == nil {
-		fmt.Println("Committed successfully")
+		r.logger.Println("Committed successfully")
 	}
 	return err
 }
@@ -1555,7 +1555,7 @@ func (r *Repo) Commit() error {
 func (r *Repo) Clean() error {
 	err := r.local.Clean()
 	if err == nil {
-		fmt.Println("Removed all staged metadata and target files")
+		r.logger.Println("Removed all staged metadata and target files")
 	}
 	return err
 }

From 4780a8c798b2c8494572b2684d68843214d5ef06 Mon Sep 17 00:00:00 2001
From: Asra Ali <asraa@google.com>
Date: Mon, 19 Sep 2022 10:16:02 -0400
Subject: [PATCH 3/4] remove logger from client

Signed-off-by: Asra Ali <asraa@google.com>
---
 client/client.go                       | 27 +++-----------------
 client/delegations.go                  |  3 +--
 internal/fsutil/perm_test.go           |  2 --
 local_store.go                         | 31 +++++++++++++++++++++--
 pkg/deprecated/deprecated_repo_test.go | 11 +--------
 pkg/keys/deprecated_ecdsa.go           | 26 +++-----------------
 pkg/keys/deprecated_ecdsa_test.go      | 21 ----------------
 pkg/keys/ecdsa.go                      |  2 +-
 pkg/keys/ed25519.go                    |  2 +-
 pkg/keys/keys.go                       | 13 ++--------
 pkg/keys/rsa.go                        |  2 +-
 repo.go                                |  7 +++---
 repo_test.go                           |  9 ++++++-
 verify/db.go                           | 34 ++++++--------------------
 14 files changed, 62 insertions(+), 128 deletions(-)

diff --git a/client/client.go b/client/client.go
index 8e226905..17ddc980 100644
--- a/client/client.go
+++ b/client/client.go
@@ -5,7 +5,6 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"io"
-	"log"
 
 	"github.com/theupdateframework/go-tuf/data"
 	"github.com/theupdateframework/go-tuf/util"
@@ -89,10 +88,6 @@ type Client struct {
 	// consistent snapshots (as specified in root.json)
 	consistentSnapshot bool
 
-	// this is an optional log writer.
-	// if nil, uses io.Discard
-	logger *log.Logger
-
 	// MaxDelegations limits by default the number of delegations visited for any
 	// target
 	MaxDelegations int
@@ -101,26 +96,13 @@ type Client struct {
 	MaxRootRotations int
 }
 
-type ClientOpts func(c *Client)
-
-func WithLogger(logger *log.Logger) ClientOpts {
-	return func(c *Client) {
-		c.logger = logger
-	}
-}
-
-func NewClient(local LocalStore, remote RemoteStore, opts ...ClientOpts) *Client {
-	client := &Client{
+func NewClient(local LocalStore, remote RemoteStore) *Client {
+	return &Client{
 		local:            local,
 		remote:           remote,
 		MaxDelegations:   defaultMaxDelegations,
 		MaxRootRotations: defaultMaxRootRotations,
-		logger:           log.New(io.Discard, "", 0),
-	}
-	for _, opt := range opts {
-		opt(client)
 	}
-	return client
 }
 
 // Init initializes a local repository from root metadata.
@@ -470,8 +452,7 @@ func (c *Client) loadAndVerifyRootMeta(rootJSON []byte, ignoreExpiredCheck bool)
 	if err := json.Unmarshal(s.Signed, root); err != nil {
 		return err
 	}
-
-	ndb := verify.NewDB(verify.WithLogger(c.logger))
+	ndb := verify.NewDB()
 	for id, k := range root.Keys {
 		if err := ndb.AddKey(id, k); err != nil {
 			return err
@@ -519,7 +500,7 @@ func (c *Client) verifyRoot(aJSON []byte, bJSON []byte) (*data.Root, error) {
 		return nil, err
 	}
 
-	ndb := verify.NewDB(verify.WithLogger(c.logger))
+	ndb := verify.NewDB()
 	for id, k := range aRoot.Keys {
 		if err := ndb.AddKey(id, k); err != nil {
 			return nil, err
diff --git a/client/delegations.go b/client/delegations.go
index 773226c7..de3e6647 100644
--- a/client/delegations.go
+++ b/client/delegations.go
@@ -43,8 +43,7 @@ func (c *Client) getTargetFileMeta(target string) (data.TargetFileMeta, error) {
 		}
 
 		if targets.Delegations != nil {
-			delegationsDB, err := verify.NewDBFromDelegations(targets.Delegations,
-				verify.WithLogger(c.logger))
+			delegationsDB, err := verify.NewDBFromDelegations(targets.Delegations)
 			if err != nil {
 				return data.TargetFileMeta{}, err
 			}
diff --git a/internal/fsutil/perm_test.go b/internal/fsutil/perm_test.go
index 6061d291..f80ef94a 100644
--- a/internal/fsutil/perm_test.go
+++ b/internal/fsutil/perm_test.go
@@ -4,7 +4,6 @@
 package fsutil
 
 import (
-	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -59,7 +58,6 @@ func TestEnsureMaxPermissions(t *testing.T) {
 	assert.NoError(t, err)
 	err = EnsureMaxPermissions(fi, os.FileMode(0222))
 	assert.Error(t, err)
-	fmt.Println(err)
 
 	// Check matching due to more restrictive perms on file
 	err = os.Chmod(p, 0444)
diff --git a/local_store.go b/local_store.go
index 1b4a7f60..fee03f31 100644
--- a/local_store.go
+++ b/local_store.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"log"
 	"os"
 	"path/filepath"
 	"strings"
@@ -197,18 +198,44 @@ type persistedKeys struct {
 	Data      json.RawMessage `json:"data"`
 }
 
+type StoreOpts struct {
+	Logger   *log.Logger
+	PassFunc util.PassphraseFunc
+}
+
 func FileSystemStore(dir string, p util.PassphraseFunc) LocalStore {
 	return &fileSystemStore{
 		dir:            dir,
 		passphraseFunc: p,
+		logger:         log.New(io.Discard, "", 0),
 		signerForKeyID: make(map[string]keys.Signer),
 		keyIDsForRole:  make(map[string][]string),
 	}
 }
 
+func FileSystemStoreWithOpts(dir string, opts ...StoreOpts) LocalStore {
+	store := &fileSystemStore{
+		dir:            dir,
+		passphraseFunc: nil,
+		logger:         log.New(io.Discard, "", 0),
+		signerForKeyID: make(map[string]keys.Signer),
+		keyIDsForRole:  make(map[string][]string),
+	}
+	for _, opt := range opts {
+		if opt.Logger != nil {
+			store.logger = opt.Logger
+		}
+		if opt.PassFunc != nil {
+			store.passphraseFunc = opt.PassFunc
+		}
+	}
+	return store
+}
+
 type fileSystemStore struct {
 	dir            string
 	passphraseFunc util.PassphraseFunc
+	logger         *log.Logger
 
 	signerForKeyID map[string]keys.Signer
 	keyIDsForRole  map[string][]string
@@ -526,7 +553,7 @@ func (f *fileSystemStore) ChangePassphrase(role string) error {
 	keys, _, err := f.loadPrivateKeys(role)
 	if err != nil {
 		if os.IsNotExist(err) {
-			fmt.Printf("Failed to change passphrase. Missing keys file for %s role. \n", role)
+			f.logger.Printf("Failed to change passphrase. Missing keys file for %s role. \n", role)
 		}
 		return err
 	}
@@ -548,7 +575,7 @@ func (f *fileSystemStore) ChangePassphrase(role string) error {
 	if err := util.AtomicallyWriteFile(f.keysPath(role), append(data, '\n'), 0600); err != nil {
 		return err
 	}
-	fmt.Printf("Successfully changed passphrase for %s keys file\n", role)
+	f.logger.Printf("Successfully changed passphrase for %s keys file\n", role)
 	return nil
 }
 
diff --git a/pkg/deprecated/deprecated_repo_test.go b/pkg/deprecated/deprecated_repo_test.go
index 9500219f..6d194ab5 100644
--- a/pkg/deprecated/deprecated_repo_test.go
+++ b/pkg/deprecated/deprecated_repo_test.go
@@ -1,14 +1,11 @@
 package deprecated
 
 import (
-	"bytes"
 	"crypto"
 	"crypto/elliptic"
 	"crypto/rand"
 	"crypto/sha256"
 	"encoding/json"
-	"log"
-	"strings"
 	"testing"
 
 	"github.com/secure-systems-lab/go-securesystemslib/cjson"
@@ -37,10 +34,7 @@ func genKey(c *C, r *repo.Repo, role string) []string {
 func (rs *RepoSuite) TestDeprecatedHexEncodedKeysSucceed(c *C) {
 	files := map[string][]byte{"foo.txt": []byte("foo")}
 	local := repo.MemoryStore(make(map[string]json.RawMessage), files)
-	var logBytes bytes.Buffer
-	opts := repo.WithLogger(log.New(&logBytes, "", 0))
-
-	r, err := repo.NewRepoWithOpts(local, opts)
+	r, err := repo.NewRepo(local)
 	c.Assert(err, IsNil)
 
 	r.Init(false)
@@ -85,7 +79,4 @@ func (rs *RepoSuite) TestDeprecatedHexEncodedKeysSucceed(c *C) {
 	c.Assert(r.Snapshot(), IsNil)
 	c.Assert(r.Timestamp(), IsNil)
 	c.Assert(r.Commit(), IsNil)
-
-	// Check logs.
-	c.Assert(strings.Contains(logBytes.String(), keys.WarnDeprecatedEcdsaKey), Equals, true)
 }
diff --git a/pkg/keys/deprecated_ecdsa.go b/pkg/keys/deprecated_ecdsa.go
index d12a22bf..6d48c9d6 100644
--- a/pkg/keys/deprecated_ecdsa.go
+++ b/pkg/keys/deprecated_ecdsa.go
@@ -9,25 +9,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"log"
 
 	"github.com/theupdateframework/go-tuf/data"
 )
 
-var (
-	WarnDeprecatedEcdsaKey = "tuf: warning using deprecated ecdsa hex-encoded keys"
-)
-
-func NewDeprecatedEcdsaVerifier(opts ...VerifierOpts) Verifier {
-	verifier := &ecdsaVerifierWithDeprecatedSupport{
-		logger: log.New(io.Discard, "", log.LstdFlags),
-	}
-	for _, opt := range opts {
-		if opt.Logger != nil {
-			verifier.logger = opt.Logger
-		}
-	}
-	return verifier
+func NewDeprecatedEcdsaVerifier() Verifier {
+	return &ecdsaVerifierWithDeprecatedSupport{}
 }
 
 type ecdsaVerifierWithDeprecatedSupport struct {
@@ -35,8 +22,6 @@ type ecdsaVerifierWithDeprecatedSupport struct {
 	// This will switch based on whether this is a PEM-encoded key
 	// or a deprecated hex-encoded key.
 	Verifier
-	// This is used to write the deprecated warning to.
-	logger *log.Logger
 }
 
 func (p *ecdsaVerifierWithDeprecatedSupport) UnmarshalPublicKey(key *data.PublicKey) error {
@@ -44,9 +29,7 @@ func (p *ecdsaVerifierWithDeprecatedSupport) UnmarshalPublicKey(key *data.Public
 	pemVerifier := &EcdsaVerifier{}
 	if err := pemVerifier.UnmarshalPublicKey(key); err != nil {
 		// Try the deprecated hex-encoded verifier
-		hexVerifier := &deprecatedP256Verifier{
-			logger: p.logger,
-		}
+		hexVerifier := &deprecatedP256Verifier{}
 		if err := hexVerifier.UnmarshalPublicKey(key); err != nil {
 			return err
 		}
@@ -67,8 +50,6 @@ func (p *ecdsaVerifierWithDeprecatedSupport) UnmarshalPublicKey(key *data.Public
 type deprecatedP256Verifier struct {
 	PublicKey data.HexBytes `json:"public"`
 	key       *data.PublicKey
-	// This is used to write the deprecated warning to.
-	logger *log.Logger
 }
 
 func (p *deprecatedP256Verifier) Public() string {
@@ -116,6 +97,5 @@ func (p *deprecatedP256Verifier) UnmarshalPublicKey(key *data.PublicKey) error {
 	}
 
 	p.key = key
-	p.logger.Print(WarnDeprecatedEcdsaKey)
 	return nil
 }
diff --git a/pkg/keys/deprecated_ecdsa_test.go b/pkg/keys/deprecated_ecdsa_test.go
index 57563b29..ddfaa84d 100644
--- a/pkg/keys/deprecated_ecdsa_test.go
+++ b/pkg/keys/deprecated_ecdsa_test.go
@@ -1,7 +1,6 @@
 package keys
 
 import (
-	"bytes"
 	"crypto"
 	"crypto/ecdsa"
 	"crypto/elliptic"
@@ -9,8 +8,6 @@ import (
 	"crypto/sha256"
 	"encoding/json"
 	"errors"
-	"log"
-	"strings"
 
 	"github.com/theupdateframework/go-tuf/data"
 	. "gopkg.in/check.v1"
@@ -130,21 +127,3 @@ func (DeprecatedECDSASuite) TestMarshalUnmarshalPublicKey(c *C) {
 
 	c.Assert(deprecatedEcdsa.MarshalPublicKey(), DeepEquals, pub)
 }
-
-func (DeprecatedECDSASuite) TestLogMessageWriter(c *C) {
-	signer, err := generatedDeprecatedSigner()
-	c.Assert(err, IsNil)
-
-	pub := signer.PublicData()
-
-	var logBytes bytes.Buffer
-	opts := WithLogger(log.New(&logBytes, "", 0))
-
-	deprecatedEcdsa := NewDeprecatedEcdsaVerifier(opts)
-	err = deprecatedEcdsa.UnmarshalPublicKey(pub)
-	c.Assert(err, IsNil)
-	c.Assert(strings.TrimSuffix(logBytes.String(), "\n"), Equals,
-		WarnDeprecatedEcdsaKey)
-
-	c.Assert(deprecatedEcdsa.MarshalPublicKey(), DeepEquals, pub)
-}
diff --git a/pkg/keys/ecdsa.go b/pkg/keys/ecdsa.go
index c7083e8a..ee93e330 100644
--- a/pkg/keys/ecdsa.go
+++ b/pkg/keys/ecdsa.go
@@ -24,7 +24,7 @@ func init() {
 	SignerMap.Store(data.KeyTypeECDSA_SHA2_P256, newEcdsaSigner)
 }
 
-func NewEcdsaVerifier(_ ...VerifierOpts) Verifier {
+func NewEcdsaVerifier() Verifier {
 	return &EcdsaVerifier{}
 }
 
diff --git a/pkg/keys/ed25519.go b/pkg/keys/ed25519.go
index f7309b1b..1e4c66cc 100644
--- a/pkg/keys/ed25519.go
+++ b/pkg/keys/ed25519.go
@@ -23,7 +23,7 @@ func NewEd25519Signer() Signer {
 	return &ed25519Signer{}
 }
 
-func NewEd25519Verifier(_ ...VerifierOpts) Verifier {
+func NewEd25519Verifier() Verifier {
 	return &ed25519Verifier{}
 }
 
diff --git a/pkg/keys/keys.go b/pkg/keys/keys.go
index 7ac9c13e..dc5f3ea2 100644
--- a/pkg/keys/keys.go
+++ b/pkg/keys/keys.go
@@ -3,7 +3,6 @@ package keys
 import (
 	"errors"
 	"fmt"
-	"log"
 	"sync"
 
 	"github.com/theupdateframework/go-tuf/data"
@@ -58,20 +57,12 @@ type Signer interface {
 	SignMessage(message []byte) ([]byte, error)
 }
 
-type VerifierOpts struct {
-	Logger *log.Logger
-}
-
-func WithLogger(logger *log.Logger) VerifierOpts {
-	return VerifierOpts{logger}
-}
-
-func GetVerifier(key *data.PublicKey, opts ...VerifierOpts) (Verifier, error) {
+func GetVerifier(key *data.PublicKey) (Verifier, error) {
 	st, ok := VerifierMap.Load(key.Type)
 	if !ok {
 		return nil, ErrInvalidKey
 	}
-	s := st.(func(opts ...VerifierOpts) Verifier)(opts...)
+	s := st.(func() Verifier)()
 	if err := s.UnmarshalPublicKey(key); err != nil {
 		return nil, fmt.Errorf("tuf: error unmarshalling key: %w", err)
 	}
diff --git a/pkg/keys/rsa.go b/pkg/keys/rsa.go
index 3fc82cde..618f104e 100644
--- a/pkg/keys/rsa.go
+++ b/pkg/keys/rsa.go
@@ -21,7 +21,7 @@ func init() {
 	SignerMap.Store(data.KeyTypeRSASSA_PSS_SHA256, newRsaSigner)
 }
 
-func newRsaVerifier(_ ...VerifierOpts) Verifier {
+func newRsaVerifier() Verifier {
 	return &rsaVerifier{}
 }
 
diff --git a/repo.go b/repo.go
index cb4fb976..cce0020f 100644
--- a/repo.go
+++ b/repo.go
@@ -137,7 +137,7 @@ func (r *Repo) Init(consistentSnapshot bool) error {
 }
 
 func (r *Repo) topLevelKeysDB() (*verify.DB, error) {
-	db := verify.NewDB(verify.WithLogger(r.logger))
+	db := verify.NewDB()
 	root, err := r.root()
 	if err != nil {
 		return nil, err
@@ -975,7 +975,7 @@ func (r *Repo) delegatorDBs(delegateeRole string) ([]*verify.DB, error) {
 			continue
 		}
 
-		db, err := verify.NewDBFromDelegations(t.Delegations, verify.WithLogger(r.logger))
+		db, err := verify.NewDBFromDelegations(t.Delegations)
 		if err != nil {
 			return nil, err
 		}
@@ -1024,8 +1024,7 @@ func (r *Repo) targetDelegationForPath(path string, preferredRole string) (*data
 		}
 
 		if targetsMeta.Delegations != nil && len(targetsMeta.Delegations.Roles) > 0 {
-			db, err := verify.NewDBFromDelegations(targetsMeta.Delegations,
-				verify.WithLogger(r.logger))
+			db, err := verify.NewDBFromDelegations(targetsMeta.Delegations)
 			if err != nil {
 				return nil, nil, err
 			}
diff --git a/repo_test.go b/repo_test.go
index 2f3aebb4..d841bb59 100644
--- a/repo_test.go
+++ b/repo_test.go
@@ -9,6 +9,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"log"
 	"os"
 	"path"
 	"path/filepath"
@@ -1422,7 +1423,12 @@ func (rs *RepoSuite) TestKeyPersistence(c *C) {
 	// Test changing the passphrase
 	// 1. Create a secure store with a passphrase (create new object and temp folder so we discard any previous state)
 	tmp = newTmpDir(c)
-	store = FileSystemStore(tmp.path, testPassphraseFunc)
+	var logBytes bytes.Buffer
+	storeOpts := StoreOpts{
+		Logger:   log.New(&logBytes, "", 0),
+		PassFunc: testPassphraseFunc,
+	}
+	store = FileSystemStoreWithOpts(tmp.path, storeOpts)
 
 	// 1.5. Changing passphrase works for top-level and delegated roles.
 	r, err := NewRepo(store)
@@ -1433,6 +1439,7 @@ func (rs *RepoSuite) TestKeyPersistence(c *C) {
 
 	// 2. Test changing the passphrase when the keys file does not exist - should FAIL
 	c.Assert(store.(PassphraseChanger).ChangePassphrase("root"), NotNil)
+	c.Assert(strings.Contains(logBytes.String(), "Missing keys file"), Equals, true)
 
 	// 3. Generate a new key
 	signer, err = keys.GenerateEd25519Key()
diff --git a/verify/db.go b/verify/db.go
index acaf7b6e..04f5bf1c 100644
--- a/verify/db.go
+++ b/verify/db.go
@@ -1,9 +1,6 @@
 package verify
 
 import (
-	"io"
-	"log"
-
 	"github.com/theupdateframework/go-tuf/data"
 	"github.com/theupdateframework/go-tuf/internal/roles"
 	"github.com/theupdateframework/go-tuf/pkg/keys"
@@ -22,33 +19,22 @@ func (r *Role) ValidKey(id string) bool {
 type DB struct {
 	roles     map[string]*Role
 	verifiers map[string]keys.Verifier
-	logger    *log.Logger
-}
-
-type DBOpts func(db *DB)
-
-func WithLogger(logger *log.Logger) DBOpts {
-	return func(db *DB) {
-		db.logger = logger
-	}
 }
 
-func NewDB(opts ...DBOpts) *DB {
-	db := &DB{
+func NewDB() *DB {
+	return &DB{
 		roles:     make(map[string]*Role),
 		verifiers: make(map[string]keys.Verifier),
-		logger:    log.New(io.Discard, "", 0),
-	}
-	for _, opt := range opts {
-		opt(db)
 	}
-	return db
 }
 
 // NewDBFromDelegations returns a DB that verifies delegations
 // of a given Targets.
-func NewDBFromDelegations(d *data.Delegations, opts ...DBOpts) (*DB, error) {
-	db := NewDB(opts...)
+func NewDBFromDelegations(d *data.Delegations) (*DB, error) {
+	db := &DB{
+		roles:     make(map[string]*Role, len(d.Roles)),
+		verifiers: make(map[string]keys.Verifier, len(d.Keys)),
+	}
 	for _, r := range d.Roles {
 		if _, ok := roles.TopLevelRoles[r.Name]; ok {
 			return nil, ErrInvalidDelegatedRole
@@ -67,11 +53,7 @@ func NewDBFromDelegations(d *data.Delegations, opts ...DBOpts) (*DB, error) {
 }
 
 func (db *DB) AddKey(id string, k *data.PublicKey) error {
-	opts := make([]keys.VerifierOpts, 0)
-	if db.logger != nil {
-		opts = append(opts, keys.WithLogger(db.logger))
-	}
-	verifier, err := keys.GetVerifier(k, opts...)
+	verifier, err := keys.GetVerifier(k)
 	if err != nil {
 		return err // ErrInvalidKey
 	}

From ff7c5b69b7066f0bbce02140a5235892d5761806 Mon Sep 17 00:00:00 2001
From: Asra Ali <asraa@google.com>
Date: Mon, 19 Sep 2022 10:54:45 -0400
Subject: [PATCH 4/4] add linter rule prohibiting fmt.Print and fix cmd/

Signed-off-by: Asra Ali <asraa@google.com>
---
 .golangci.yml            | 1 +
 cmd/tuf-client/main.go   | 3 ++-
 cmd/tuf/gen_key.go       | 5 +++--
 cmd/tuf/get_threshold.go | 3 ++-
 cmd/tuf/main.go          | 8 ++++++--
 cmd/tuf/payload.go       | 3 ++-
 cmd/tuf/set_threshold.go | 3 ++-
 cmd/tuf/sign_payload.go  | 2 +-
 8 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/.golangci.yml b/.golangci.yml
index 6e8bf3c8..570c05d6 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -13,3 +13,4 @@ linters:
     - gosimple
     - unused
     - typecheck
+    - forbidigo
diff --git a/cmd/tuf-client/main.go b/cmd/tuf-client/main.go
index 15d03fad..25a32005 100644
--- a/cmd/tuf-client/main.go
+++ b/cmd/tuf-client/main.go
@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"log"
+	"os"
 
 	docopt "github.com/flynn/go-docopt"
 	tuf "github.com/theupdateframework/go-tuf/client"
@@ -32,7 +33,7 @@ See "tuf-client help <command>" for more information on a specific command.
 
 	if cmd == "help" {
 		if len(cmdArgs) == 0 { // `tuf-client help`
-			fmt.Println(usage)
+			fmt.Fprint(os.Stderr, usage)
 			return
 		} else { // `tuf-client help <command>`
 			cmd = cmdArgs[0]
diff --git a/cmd/tuf/gen_key.go b/cmd/tuf/gen_key.go
index bd4334ae..2ad77a58 100644
--- a/cmd/tuf/gen_key.go
+++ b/cmd/tuf/gen_key.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"os"
 	"time"
 
 	"github.com/flynn/go-docopt"
@@ -39,7 +40,7 @@ func cmdGenKey(args *docopt.Args, repo *tuf.Repo) error {
 		string(data.KeySchemeRSASSA_PSS_SHA256):
 		keyScheme = data.KeyScheme(t)
 	default:
-		fmt.Println("Using default key scheme", keyScheme)
+		fmt.Fprint(os.Stderr, "Using default key scheme", keyScheme)
 	}
 
 	var err error
@@ -57,7 +58,7 @@ func cmdGenKey(args *docopt.Args, repo *tuf.Repo) error {
 		return err
 	}
 	for _, id := range keyids {
-		fmt.Println("Generated", role, keyScheme, "key with ID", id)
+		fmt.Fprintf(os.Stdout, "Generated %s %s key with ID %s", role, keyScheme, id)
 	}
 	return nil
 }
diff --git a/cmd/tuf/get_threshold.go b/cmd/tuf/get_threshold.go
index e40ec26e..a0d78fdd 100644
--- a/cmd/tuf/get_threshold.go
+++ b/cmd/tuf/get_threshold.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"os"
 
 	"github.com/flynn/go-docopt"
 	"github.com/theupdateframework/go-tuf"
@@ -23,6 +24,6 @@ func cmdGetThreshold(args *docopt.Args, repo *tuf.Repo) error {
 		return err
 	}
 
-	fmt.Println("The threshold for", role, "role is", threshold)
+	fmt.Fprintf(os.Stdout, "The threshold for %s role is %d", role, threshold)
 	return nil
 }
diff --git a/cmd/tuf/main.go b/cmd/tuf/main.go
index f2b73972..6ee220b2 100644
--- a/cmd/tuf/main.go
+++ b/cmd/tuf/main.go
@@ -58,7 +58,7 @@ See "tuf help <command>" for more information on a specific command
 
 	if cmd == "help" {
 		if len(cmdArgs) == 0 { // `tuf help`
-			fmt.Println(usage)
+			fmt.Fprint(os.Stderr, usage)
 			return
 		} else { // `tuf help <command>`
 			cmd = cmdArgs[0]
@@ -115,7 +115,11 @@ func runCommand(name string, args []string, dir string, insecure bool) error {
 	if !insecure {
 		p = getPassphrase
 	}
-	repo, err := tuf.NewRepo(tuf.FileSystemStore(dir, p))
+	logger := log.New(os.Stdout, "", 0)
+	storeOpts := tuf.StoreOpts{Logger: logger, PassFunc: p}
+
+	repo, err := tuf.NewRepoWithOpts(tuf.FileSystemStoreWithOpts(dir, storeOpts),
+		tuf.WithLogger(logger))
 	if err != nil {
 		return err
 	}
diff --git a/cmd/tuf/payload.go b/cmd/tuf/payload.go
index 8cc0c2ff..3ae2c891 100644
--- a/cmd/tuf/payload.go
+++ b/cmd/tuf/payload.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"os"
 
 	"github.com/flynn/go-docopt"
 	"github.com/theupdateframework/go-tuf"
@@ -20,6 +21,6 @@ func cmdPayload(args *docopt.Args, repo *tuf.Repo) error {
 	if err != nil {
 		return err
 	}
-	fmt.Print(string(p))
+	fmt.Fprint(os.Stdout, string(p))
 	return nil
 }
diff --git a/cmd/tuf/set_threshold.go b/cmd/tuf/set_threshold.go
index 57754d24..29149ff9 100644
--- a/cmd/tuf/set_threshold.go
+++ b/cmd/tuf/set_threshold.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"os"
 	"strconv"
 
 	"github.com/flynn/go-docopt"
@@ -28,6 +29,6 @@ func cmdSetThreshold(args *docopt.Args, repo *tuf.Repo) error {
 		return err
 	}
 
-	fmt.Println("The threshold for", role, "role is now", threshold)
+	fmt.Fprintf(os.Stdout, "The threshold for %s role is now %d", role, threshold)
 	return nil
 }
diff --git a/cmd/tuf/sign_payload.go b/cmd/tuf/sign_payload.go
index 8da5642b..6772972c 100644
--- a/cmd/tuf/sign_payload.go
+++ b/cmd/tuf/sign_payload.go
@@ -36,7 +36,7 @@ func cmdSignPayload(args *docopt.Args, repo *tuf.Repo) error {
 	if err != nil {
 		return err
 	}
-	fmt.Print(string(bytes))
+	fmt.Fprint(os.Stdout, string(bytes))
 
 	fmt.Fprintln(os.Stderr, "tuf: signed with", numKeys, "key(s)")
 	return nil