Skip to content

Add and use richer interfaces for signer/subtreesigner. #264

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
AlCutter merged 1 commit into from
Jul 10, 2026
Merged

Add and use richer interfaces for signer/subtreesigner. #264

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
85 changes: 44 additions & 41 deletions note/note_cosigv1.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,6 @@ const (
timestampSize = 8
)


// GenerateMLDSAKey generates a named signer and verifier key pair. The signer key skey is private and must be kept secret.
func GenerateMLDSAKey(name string) (skey string, vkey string, err error) {
if !isValidName(name) {
Expand All @@ -59,7 +58,7 @@ func GenerateMLDSAKey(name string) (skey string, vkey string, err error) {
}

// NewMLDSASigner returns a signer for MLDSA cosignature v1.
func NewMLDSASigner(skey string) (*SubtreeSigner, error) {
func NewMLDSASigner(skey string) (SubtreeSigner, error) {
priv1, skey, _ := strings.Cut(skey, "+")
priv2, skey, _ := strings.Cut(skey, "+")
name, skey, _ := strings.Cut(skey, "+")
Expand All @@ -77,8 +76,8 @@ func NewMLDSASigner(skey string) (*SubtreeSigner, error) {

// newMLDSASigner returns a signer for MLDSA cosignature v1, with the provided
// name and key bytes in the format: algo || private key.
func newMLDSASigner(name string, keyBytes []byte) (*SubtreeSigner, error) {
s := &SubtreeSigner{name: name}
func newMLDSASigner(name string, keyBytes []byte) (*subtreeSigner, error) {
s := &subtreeSigner{name: name}
if len(keyBytes) != mldsa.PrivateKeySize {
return nil, errSignerID
}
Expand Down Expand Up @@ -112,7 +111,7 @@ func newMLDSASigner(name string, keyBytes []byte) (*SubtreeSigner, error) {
sig = append(sig, sB...)
return sig, nil
}
s.verifier = &SubtreeVerifier{
s.verifier = &subtreeVerifier{
name: name,
keyHash: s.hash,
verifyNote: func(msg, sig []byte) bool { return verifyMLDSACosigV1(pubKey, name)(msg, sig) },
Expand All @@ -125,7 +124,7 @@ func newMLDSASigner(name string, keyBytes []byte) (*SubtreeSigner, error) {
}

// NewMLDSAVerifier constructs a verifier for MLDSA cosignature v1.
func NewMLDSAVerifier(vkey string) (*SubtreeVerifier, error) {
func NewMLDSAVerifier(vkey string) (SubtreeVerifier, error) {
name, vkey, _ := strings.Cut(vkey, "+")
hash16, key64, _ := strings.Cut(vkey, "+")
keyBytes, err := base64.StdEncoding.DecodeString(key64)
Expand All @@ -137,7 +136,7 @@ func NewMLDSAVerifier(vkey string) (*SubtreeVerifier, error) {
return nil, errVerifierID
}

v := &SubtreeVerifier{
v := &subtreeVerifier{
name: name,
keyHash: keyHashMLDSA(name, keyBytes),
}
Expand All @@ -162,7 +161,7 @@ func NewMLDSAVerifier(vkey string) (*SubtreeVerifier, error) {
// - an ML-DSA-44 cosignature/v1 encoded signer key (algo ID 0x06)
//
// See https://c2sp.org/tlog-cosignature for more details.
func NewSignerForCosignatureV1(skey string) (*Signer, error) {
func NewSignerForCosignatureV1(skey string) (Signer, error) {
priv1, skey, _ := strings.Cut(skey, "+")
priv2, skey, _ := strings.Cut(skey, "+")
name, skey, _ := strings.Cut(skey, "+")
Expand All @@ -172,7 +171,7 @@ func NewSignerForCosignatureV1(skey string) (*Signer, error) {
return nil, errSignerID
}

s := &Signer{name: name}
s := &signer{name: name}

alg, key := key[0], key[1:]
switch alg {
Expand Down Expand Up @@ -434,72 +433,76 @@ var (
)

// Signer is a note.Signer which also provides access to the corresponding Verifier.
type Signer struct {
type Signer interface {
note.Signer
Verifier() note.Verifier
}

// signer is a concrete implementation of the extended Signer interface above.
type signer struct {
name string
hash uint32
sign func([]byte) ([]byte, error)
verify func(msg, sig []byte) bool
}

func (s *Signer) Name() string { return s.name }
func (s *Signer) KeyHash() uint32 { return s.hash }
func (s *Signer) Sign(msg []byte) ([]byte, error) { return s.sign(msg) }
func (s *signer) Name() string { return s.name }
func (s *signer) KeyHash() uint32 { return s.hash }
func (s *signer) Sign(msg []byte) ([]byte, error) { return s.sign(msg) }

func (s *Signer) Verifier() *Verifier {
return &Verifier{
func (s *signer) Verifier() note.Verifier {
return &verifier{
name: s.name,
keyHash: s.hash,
v: s.verify,
}
}

// Verifier is a note.Verifier.
type Verifier struct {
name string
keyHash uint32
v func([]byte, []byte) bool
// SubtreeSigner is a note.Signer that can additionally produce subtree signatures, and
// provide access to a similarly capable verifier.
type SubtreeSigner interface {
note.Signer
SignSubtree(timestamp uint64, logOrigin string, start, end uint64, root []byte) ([]byte, error)
Verifier() SubtreeVerifier
}

func (v *Verifier) Name() string { return v.name }
func (v *Verifier) KeyHash() uint32 { return v.keyHash }
func (v *Verifier) Verify(msg, sig []byte) bool { return v.v(msg, sig) }

// SubtreeSigner is a signer that can produce both note and subtree signatures.
type SubtreeSigner struct {
// subtreeSigner is a concrete implementation of the extended SubtreeSigner interface above.
type subtreeSigner struct {

@roger2hk roger2hk Jul 10, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
type subtreeSigner struct {
// subtreeSigner is a concrete implementation of the extended SubtreeSigner interface above.
type subtreeSigner struct {

name string
hash uint32
signNote func([]byte) ([]byte, error)
signSubtree func(timestamp uint64, logOrigin string, start, end uint64, root []byte) ([]byte, error)
verifier *SubtreeVerifier
verifier *subtreeVerifier
}

func (s *SubtreeSigner) Name() string { return s.name }
func (s *SubtreeSigner) KeyHash() uint32 { return s.hash }
func (s *SubtreeSigner) Sign(msg []byte) ([]byte, error) { return s.signNote(msg) }
func (s *SubtreeSigner) SignSubtree(timestamp uint64, logOrigin string, start, end uint64, root []byte) ([]byte, error) {
func (s *subtreeSigner) Name() string { return s.name }
func (s *subtreeSigner) KeyHash() uint32 { return s.hash }
func (s *subtreeSigner) Sign(msg []byte) ([]byte, error) { return s.signNote(msg) }
func (s *subtreeSigner) SignSubtree(timestamp uint64, logOrigin string, start, end uint64, root []byte) ([]byte, error) {
return s.signSubtree(timestamp, logOrigin, start, end, root)
}
func (s *subtreeSigner) Verifier() SubtreeVerifier { return s.verifier }

func (s *SubtreeSigner) Verifier() *SubtreeVerifier {
return s.verifier
// SubtreeVerifier is a verifier that supports the verification of subtree signatures.
type SubtreeVerifier interface {
note.Verifier
VerifySubtree(timestamp uint64, logOrigin string, start, end uint64, hash []byte, sig []byte) bool
}

// SubtreeVerifier is a verifier that supports the verification of subtree signatures.
//
// This struct implements the note.Verifier interface to facilitate cosigning operations
// subtreeVerifier implements the note.Verifier interface to facilitate cosigning operations
// against tree roots represented as checkpoints, but it can also be used to verify
// arbitrary subtree roots using the VerifySubtree method.
type SubtreeVerifier struct {
type subtreeVerifier struct {
name string
keyHash uint32
verifyNote func([]byte, []byte) bool
verifySubtree func(timestamp uint64, logOrigin string, start, end uint64, hash []byte, sig []byte) bool
}

func (v *SubtreeVerifier) Name() string { return v.name }
func (v *SubtreeVerifier) KeyHash() uint32 { return v.keyHash }
func (v *SubtreeVerifier) Verify(msg, sig []byte) bool { return v.verifyNote(msg, sig) }
func (v *SubtreeVerifier) VerifySubtree(timestamp uint64, logOrigin string, start, end uint64, hash []byte, sig []byte) bool {
func (v *subtreeVerifier) Name() string { return v.name }
func (v *subtreeVerifier) KeyHash() uint32 { return v.keyHash }
func (v *subtreeVerifier) Verify(msg, sig []byte) bool { return v.verifyNote(msg, sig) }
func (v *subtreeVerifier) VerifySubtree(timestamp uint64, logOrigin string, start, end uint64, hash []byte, sig []byte) bool {
return v.verifySubtree(timestamp, logOrigin, start, end, hash, sig)
}

Expand Down
Loading