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//
// Copyright 2021 The Sigstore Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package dsse
import (
"context"
"crypto"
"encoding/json"
"errors"
"io"
"github.com/secure-systems-lab/go-securesystemslib/dsse"
"github.com/sigstore/sigstore/pkg/signature"
)
type wrappedMultiSigner struct {
sLAdapters []dsse.Signer
payloadType string
}
// WrapMultiSigner returns a signature.Signer that uses the DSSE encoding format
func WrapMultiSigner(payloadType string, sL ...signature.Signer) signature.Signer {
signerAdapterL := make([]dsse.Signer, 0, len(sL))
for _, s := range sL {
pub, err := s.PublicKey()
if err != nil {
return nil
}
keyID, err := dsse.SHA256KeyID(pub)
if err != nil {
keyID = ""
}
signerAdapter := &SignerAdapter{
SignatureSigner: s,
Pub: s.PublicKey,
PubKeyID: keyID, // We do not want to limit verification to a specific key.
}
signerAdapterL = append(signerAdapterL, signerAdapter)
}
return &wrappedMultiSigner{
sLAdapters: signerAdapterL,
payloadType: payloadType,
}
}
// PublicKey returns the public key associated with the signer
func (wL *wrappedMultiSigner) PublicKey(_ ...signature.PublicKeyOption) (crypto.PublicKey, error) {
return nil, errors.New("not supported for multi signatures")
}
// SignMessage signs the provided stream in the reader using the DSSE encoding format
func (wL *wrappedMultiSigner) SignMessage(r io.Reader, _ ...signature.SignOption) ([]byte, error) {
p, err := io.ReadAll(r)
if err != nil {
return nil, err
}
envSigner, err := dsse.NewEnvelopeSigner(wL.sLAdapters...)
if err != nil {
return nil, err
}
env, err := envSigner.SignPayload(context.Background(), wL.payloadType, p)
if err != nil {
return nil, err
}
return json.Marshal(env)
}
type wrappedMultiVerifier struct {
vLAdapters []dsse.Verifier
threshold int
payloadType string
}
// WrapMultiVerifier returns a signature.Verifier that uses the DSSE encoding format
func WrapMultiVerifier(payloadType string, threshold int, vL ...signature.Verifier) signature.Verifier {
verifierAdapterL := make([]dsse.Verifier, 0, len(vL))
for _, v := range vL {
pub, err := v.PublicKey()
if err != nil {
return nil
}
keyID, err := dsse.SHA256KeyID(pub)
if err != nil {
keyID = ""
}
verifierAdapter := &VerifierAdapter{
SignatureVerifier: v,
Pub: v.PublicKey,
PubKeyID: keyID, // We do not want to limit verification to a specific key.
}
verifierAdapterL = append(verifierAdapterL, verifierAdapter)
}
return &wrappedMultiVerifier{
vLAdapters: verifierAdapterL,
payloadType: payloadType,
threshold: threshold,
}
}
// PublicKey returns the public key associated with the signer
func (wL *wrappedMultiVerifier) PublicKey(_ ...signature.PublicKeyOption) (crypto.PublicKey, error) {
return nil, errors.New("not supported for multi signatures")
}
// VerifySignature verifies the signature specified in an DSSE envelope
func (wL *wrappedMultiVerifier) VerifySignature(s, _ io.Reader, _ ...signature.VerifyOption) error {
sig, err := io.ReadAll(s)
if err != nil {
return err
}
env := dsse.Envelope{}
if err := json.Unmarshal(sig, &env); err != nil {
return err
}
envVerifier, err := dsse.NewMultiEnvelopeVerifier(wL.threshold, wL.vLAdapters...)
if err != nil {
return err
}
_, err = envVerifier.Verify(context.Background(), &env)
return err
}
// WrapMultiSignerVerifier returns a signature.SignerVerifier that uses the DSSE encoding format
func WrapMultiSignerVerifier(payloadType string, threshold int, svL ...signature.SignerVerifier) signature.SignerVerifier {
signerL := make([]signature.Signer, 0, len(svL))
verifierL := make([]signature.Verifier, 0, len(svL))
for _, sv := range svL {
signerL = append(signerL, sv)
verifierL = append(verifierL, sv)
}
sL := WrapMultiSigner(payloadType, signerL...)
vL := WrapMultiVerifier(payloadType, threshold, verifierL...)
return &wrappedMultiSignerVerifier{
signer: sL,
verifier: vL,
}
}
type wrappedMultiSignerVerifier struct {
signer signature.Signer
verifier signature.Verifier
}
// PublicKey returns the public key associated with the verifier
func (w *wrappedMultiSignerVerifier) PublicKey(opts ...signature.PublicKeyOption) (crypto.PublicKey, error) {
return w.signer.PublicKey(opts...)
}
// VerifySignature verifies the signature specified in an DSSE envelope
func (w *wrappedMultiSignerVerifier) VerifySignature(s, r io.Reader, opts ...signature.VerifyOption) error {
return w.verifier.VerifySignature(s, r, opts...)
}
// SignMessage signs the provided stream in the reader using the DSSE encoding format
func (w *wrappedMultiSignerVerifier) SignMessage(r io.Reader, opts ...signature.SignOption) ([]byte, error) {
return w.signer.SignMessage(r, opts...)
}
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