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Fix signing and verification with ed25519 keys with bundles and Rekor #4414

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6 changes: 5 additions & 1 deletion cmd/cosign/cli/attest/attest.go
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ import (
"github.com/sigstore/rekor/pkg/generated/client"
"github.com/sigstore/rekor/pkg/generated/models"
"github.com/sigstore/sigstore-go/pkg/sign"
"github.com/sigstore/sigstore/pkg/signature"
"github.com/sigstore/sigstore/pkg/signature/dsse"
signatureoptions "github.com/sigstore/sigstore/pkg/signature/options"
)
Expand Down Expand Up @@ -164,11 +165,14 @@ func (c *AttestCommand) Exec(ctx context.Context, imageRef string) error {
var err error

if c.Sk || c.Slot != "" || c.KeyRef != "" || c.CertPath != "" {
// Set no load options so that Ed25519 is preferred over Ed25519ph, required for signing DSSEs
var signOpts []signature.LoadOption
c.KeyOpts.DefaultLoadOptions = &signOpts
sv, _, err = cosign_sign.SignerFromKeyOpts(ctx, c.CertPath, c.CertChainPath, c.KeyOpts)
if err != nil {
return fmt.Errorf("getting signer: %w", err)
}
keypair, err = key.NewSignerVerifierKeypair(sv, c.DefaultLoadOptions)
keypair, err = key.NewSignerVerifierKeypair(sv, &signOpts)
if err != nil {
return fmt.Errorf("creating signerverifier keypair: %w", err)
}
Expand Down
5 changes: 4 additions & 1 deletion cmd/cosign/cli/attest/attest_blob.go
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Expand Up @@ -165,11 +165,14 @@ func (c *AttestBlobCommand) Exec(ctx context.Context, artifactPath string) error
var err error

if c.Sk || c.Slot != "" || c.KeyRef != "" || c.CertPath != "" {
// Set no load options so that Ed25519 is preferred over Ed25519ph, required for signing DSSEs
var signOpts []signature.LoadOption
c.KeyOpts.DefaultLoadOptions = &signOpts
sv, _, err = cosign_sign.SignerFromKeyOpts(ctx, c.CertPath, c.CertChainPath, c.KeyOpts)
if err != nil {
return fmt.Errorf("getting signer: %w", err)
}
keypair, err = key.NewSignerVerifierKeypair(sv, c.DefaultLoadOptions)
keypair, err = key.NewSignerVerifierKeypair(sv, &signOpts)
if err != nil {
return fmt.Errorf("creating signerverifier keypair: %w", err)
}
Expand Down
5 changes: 4 additions & 1 deletion cmd/cosign/cli/sign/sign.go
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Expand Up @@ -256,11 +256,14 @@ func signDigestBundle(ctx context.Context, digest name.Digest, ko options.KeyOpt
var err error

if ko.Sk || ko.Slot != "" || ko.KeyRef != "" || signOpts.Cert != "" {
// Set no load options so that Ed25519 is preferred over Ed25519ph, required for signing DSSEs
var signLoadOpts []signature.LoadOption
ko.DefaultLoadOptions = &signLoadOpts
sv, _, err = SignerFromKeyOpts(ctx, signOpts.Cert, signOpts.CertChain, ko)
if err != nil {
return fmt.Errorf("getting signer: %w", err)
}
keypair, err = key.NewSignerVerifierKeypair(sv, ko.DefaultLoadOptions)
keypair, err = key.NewSignerVerifierKeypair(sv, &signLoadOpts)
if err != nil {
return fmt.Errorf("creating signerverifier keypair: %w", err)
}
Expand Down
1 change: 1 addition & 0 deletions cmd/cosign/cli/sign/sign_blob.go
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,7 @@ func SignBlobCmd(ro *options.RootOptions, ko options.KeyOpts, payloadPath string
var err error

if ko.Sk || ko.Slot != "" || ko.KeyRef != "" {
// Default load options prefer Ed25519ph over Ed25519, required for blobs with hashedrekord
sv, _, err = SignerFromKeyOpts(ctx, "", "", ko)
if err != nil {
return nil, fmt.Errorf("getting signer: %w", err)
Expand Down
4 changes: 3 additions & 1 deletion cmd/cosign/cli/verify/verify.go
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Expand Up @@ -240,7 +240,9 @@ func (c *VerifyCommand) Exec(ctx context.Context, images []string) (err error) {
var pubKey signature.Verifier
switch {
case keyRef != "":
pubKey, err = sigs.PublicKeyFromKeyRefWithHashAlgo(ctx, keyRef, c.HashAlgorithm)
// Set no load options so that Ed25519 is preferred over Ed25519ph, required for verifying DSSEs
var signOpts []signature.LoadOption
pubKey, err = sigs.PublicKeyFromKeyRefWithHashAlgo(ctx, keyRef, c.HashAlgorithm, &signOpts)
if err != nil {
return fmt.Errorf("loading public key: %w", err)
}
Expand Down
5 changes: 4 additions & 1 deletion cmd/cosign/cli/verify/verify_attestation.go
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Expand Up @@ -40,6 +40,7 @@ import (
"github.com/sigstore/cosign/v2/pkg/policy"
sigs "github.com/sigstore/cosign/v2/pkg/signature"
"github.com/sigstore/sigstore-go/pkg/root"
"github.com/sigstore/sigstore/pkg/signature"
)

// VerifyAttestationCommand verifies a signature on a supplied container image
Expand Down Expand Up @@ -210,7 +211,9 @@ func (c *VerifyAttestationCommand) Exec(ctx context.Context, images []string) (e
// Keys are optional!
switch {
case keyRef != "":
co.SigVerifier, err = sigs.PublicKeyFromKeyRefWithHashAlgo(ctx, keyRef, c.HashAlgorithm)
// Set no load options so that Ed25519 is preferred over Ed25519ph, required for verifying DSSEs
var signOpts []signature.LoadOption
co.SigVerifier, err = sigs.PublicKeyFromKeyRefWithHashAlgo(ctx, keyRef, c.HashAlgorithm, &signOpts)
if err != nil {
return fmt.Errorf("loading public key: %w", err)
}
Expand Down
12 changes: 10 additions & 2 deletions cmd/cosign/cli/verify/verify_blob.go
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@ import (
sgverify "github.com/sigstore/sigstore-go/pkg/verify"

"github.com/sigstore/sigstore/pkg/cryptoutils"
"github.com/sigstore/sigstore/pkg/signature"
)

func isb64(data []byte) bool {
Expand Down Expand Up @@ -117,12 +118,19 @@ func (c *VerifyBlobCmd) Exec(ctx context.Context, blobRef string) error {
NewBundleFormat: c.KeyOpts.NewBundleFormat && checkNewBundle(c.BundlePath),
}

if !c.IgnoreTlog {
// To maintain backwards compatibility with older cosign versions,
// we do not use ed25519ph for ed25519 keys when the signatures are not
// uploaded to the Tlog.
c.DefaultLoadOptions = &[]signature.LoadOption{}
}

// Keys are optional!
var cert *x509.Certificate
opts := make([]static.Option, 0)
switch {
case c.KeyRef != "":
co.SigVerifier, err = sigs.PublicKeyFromKeyRefWithHashAlgo(ctx, c.KeyRef, c.HashAlgorithm)
co.SigVerifier, err = sigs.PublicKeyFromKeyRefWithHashAlgo(ctx, c.KeyRef, c.HashAlgorithm, c.DefaultLoadOptions)
if err != nil {
return fmt.Errorf("loading public key: %w", err)
}
Expand Down Expand Up @@ -265,7 +273,7 @@ func (c *VerifyBlobCmd) Exec(ctx context.Context, blobRef string) error {
bundleCert, err := loadCertFromPEM(certBytes)
if err != nil {
// check if cert is actually a public key
co.SigVerifier, err = sigs.LoadPublicKeyRaw(certBytes, crypto.SHA256)
co.SigVerifier, err = sigs.LoadPublicKeyRaw(certBytes, crypto.SHA256, c.DefaultLoadOptions)
if err != nil {
return fmt.Errorf("loading verifier from bundle: %w", err)
}
Expand Down
9 changes: 7 additions & 2 deletions cmd/cosign/cli/verify/verify_blob_attestation.go
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@ import (
"github.com/sigstore/sigstore-go/pkg/root"
sgverify "github.com/sigstore/sigstore-go/pkg/verify"
"github.com/sigstore/sigstore/pkg/cryptoutils"
"github.com/sigstore/sigstore/pkg/signature"
)

// VerifyBlobAttestationCommand verifies an attestation on a supplied blob
Expand Down Expand Up @@ -127,12 +128,16 @@ func (c *VerifyBlobAttestationCommand) Exec(ctx context.Context, artifactPath st
NewBundleFormat: c.NewBundleFormat && checkNewBundle(c.BundlePath),
}

// Set no load options so that Ed25519 is preferred over Ed25519ph, required for verifying DSSEs
var signOpts []signature.LoadOption
c.DefaultLoadOptions = &signOpts

// Keys are optional!
var cert *x509.Certificate
opts := make([]static.Option, 0)
switch {
case c.KeyRef != "":
co.SigVerifier, err = sigs.PublicKeyFromKeyRefWithHashAlgo(ctx, c.KeyRef, c.HashAlgorithm)
co.SigVerifier, err = sigs.PublicKeyFromKeyRefWithHashAlgo(ctx, c.KeyRef, c.HashAlgorithm, c.DefaultLoadOptions)
if err != nil {
return fmt.Errorf("loading public key: %w", err)
}
Expand Down Expand Up @@ -329,7 +334,7 @@ func (c *VerifyBlobAttestationCommand) Exec(ctx context.Context, artifactPath st
bundleCert, err := loadCertFromPEM(certBytes)
if err != nil {
// check if cert is actually a public key
co.SigVerifier, err = sigs.LoadPublicKeyRaw(certBytes, crypto.SHA256)
co.SigVerifier, err = sigs.LoadPublicKeyRaw(certBytes, crypto.SHA256, c.DefaultLoadOptions)
if err != nil {
return fmt.Errorf("loading verifier from bundle: %w", err)
}
Expand Down
17 changes: 12 additions & 5 deletions internal/key/svkeypair.go
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Original file line number Diff line number Diff line change
Expand Up @@ -125,13 +125,20 @@ func (k *SignerVerifierKeypair) GetPublicKeyPem() (string, error) {

// SignData signs the given data with the SignerVerifier.
func (k *SignerVerifierKeypair) SignData(ctx context.Context, data []byte) ([]byte, []byte, error) {
h := k.sigAlg.GetHashType().New()
h.Write(data)
digest := h.Sum(nil)
sOpts := []signature.SignOption{signatureoptions.WithContext(ctx), signatureoptions.WithDigest(digest)}
sOpts := []signature.SignOption{signatureoptions.WithContext(ctx)}

hf := k.sigAlg.GetHashType()
dataToSign := data
// RSA, ECDSA, and Ed25519ph sign a digest, while pure Ed25519's interface takes data and hashes during signing
if hf != crypto.Hash(0) {
hasher := hf.New()
hasher.Write(data)
dataToSign = hasher.Sum(nil)
sOpts = append(sOpts, signatureoptions.WithDigest(dataToSign))
}
sig, err := k.sv.SignMessage(bytes.NewReader(data), sOpts...)
if err != nil {
return nil, nil, err
}
return sig, digest, nil
return sig, dataToSign, nil
}
23 changes: 21 additions & 2 deletions internal/key/svkeypair_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ import (
protocommon "github.com/sigstore/protobuf-specs/gen/pb-go/common/v1"
"github.com/sigstore/sigstore/pkg/cryptoutils"
"github.com/sigstore/sigstore/pkg/signature"
"github.com/sigstore/sigstore/pkg/signature/options"
)

// mockSignerVerifier is a mock implementation of signature.SignerVerifier for testing.
Expand Down Expand Up @@ -61,7 +62,7 @@ func (m *mockSignerVerifier) VerifySignature(_, _ io.Reader, _ ...signature.Veri
return errors.New("not implemented")
}

func TestNewKMSKeypair(t *testing.T) {
func TestNewSignerVerifierKeypair(t *testing.T) {
ecdsaPriv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
t.Fatalf("failed to generate ecdsa key: %v", err)
Expand All @@ -78,6 +79,7 @@ func TestNewKMSKeypair(t *testing.T) {
testCases := []struct {
name string
sv signature.SignerVerifier
prehash bool
expectErr bool
errMsg string
}{
Expand All @@ -102,6 +104,14 @@ func TestNewKMSKeypair(t *testing.T) {
},
expectErr: false,
},
{
name: "ED25519ph key",
sv: &mockSignerVerifier{
pubKey: ed25519Priv.Public(),
},
prehash: true,
expectErr: false,
},
{
name: "Unsupported key type",
sv: &mockSignerVerifier{
Expand All @@ -122,7 +132,11 @@ func TestNewKMSKeypair(t *testing.T) {

for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
kp, err := NewSignerVerifierKeypair(tc.sv, nil)
var loadOpts []signature.LoadOption
if tc.prehash {
loadOpts = []signature.LoadOption{options.WithED25519ph()}
}
kp, err := NewSignerVerifierKeypair(tc.sv, &loadOpts)
if tc.expectErr {
if err == nil {
t.Errorf("expected an error, but got none")
Expand All @@ -137,6 +151,11 @@ func TestNewKMSKeypair(t *testing.T) {
t.Error("expected a keypair, but got nil")
}
}
if !tc.expectErr {
if _, _, err := kp.SignData(context.Background(), []byte("data")); err != nil {
t.Errorf("unexpected error: %v", err)
}
}
})
}
}
Expand Down
7 changes: 6 additions & 1 deletion pkg/cosign/bundle/sign.go
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@ import (
"github.com/sigstore/sigstore-go/pkg/root"
"github.com/sigstore/sigstore-go/pkg/sign"
"github.com/sigstore/sigstore/pkg/signature"
"github.com/sigstore/sigstore/pkg/signature/options"
"google.golang.org/protobuf/encoding/protojson"
)

Expand Down Expand Up @@ -63,7 +64,11 @@ func SignData(ctx context.Context, content sign.Content, keypair sign.Keypair, i
if err != nil {
log.Fatal(err)
}
verifier, err := signature.LoadDefaultVerifier(pubKey)
var verifierOpts []signature.LoadOption
if _, ok := content.(*sign.PlainData); ok {
verifierOpts = append(verifierOpts, options.WithED25519ph())
}
verifier, err := signature.LoadDefaultVerifier(pubKey, verifierOpts...)
if err != nil {
log.Fatal(err)
}
Expand Down
25 changes: 15 additions & 10 deletions pkg/signature/keys.go
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Original file line number Diff line number Diff line change
Expand Up @@ -31,16 +31,17 @@ import (
"github.com/sigstore/sigstore/pkg/signature"

"github.com/sigstore/sigstore/pkg/signature/kms"
"github.com/sigstore/sigstore/pkg/signature/options"
)

// LoadPublicKey is a wrapper for VerifierForKeyRef, hardcoding SHA256 as the hash algorithm
func LoadPublicKey(ctx context.Context, keyRef string) (verifier signature.Verifier, err error) {
return VerifierForKeyRef(ctx, keyRef, crypto.SHA256)
return VerifierForKeyRef(ctx, keyRef, crypto.SHA256, nil)
}

// VerifierForKeyRef parses the given keyRef, loads the key and returns an appropriate
// verifier using the provided hash algorithm
func VerifierForKeyRef(ctx context.Context, keyRef string, hashAlgorithm crypto.Hash) (verifier signature.Verifier, err error) {
func VerifierForKeyRef(ctx context.Context, keyRef string, hashAlgorithm crypto.Hash, defaultLoadOptions *[]signature.LoadOption) (verifier signature.Verifier, err error) {
// The key could be plaintext, in a file, at a URL, or in KMS.
var perr *kms.ProviderNotFoundError
kmsKey, err := kms.Get(ctx, keyRef, hashAlgorithm)
Expand Down Expand Up @@ -69,7 +70,9 @@ func VerifierForKeyRef(ctx context.Context, keyRef string, hashAlgorithm crypto.
return nil, fmt.Errorf("pem to public key: %w", err)
}

return signature.LoadVerifier(pubKey, hashAlgorithm)
opts := *cosign.GetDefaultLoadOptions(defaultLoadOptions)
opts = append(opts, options.WithHash(hashAlgorithm))
return signature.LoadVerifierWithOpts(pubKey, opts...)
}

func loadKey(keyPath string, pf cosign.PassFunc, defaultLoadOptions *[]signature.LoadOption) (signature.SignerVerifier, error) {
Expand All @@ -88,12 +91,14 @@ func loadKey(keyPath string, pf cosign.PassFunc, defaultLoadOptions *[]signature
}

// LoadPublicKeyRaw loads a verifier from a PEM-encoded public key
func LoadPublicKeyRaw(raw []byte, hashAlgorithm crypto.Hash) (signature.Verifier, error) {
func LoadPublicKeyRaw(raw []byte, hashAlgorithm crypto.Hash, defaultLoadOptions *[]signature.LoadOption) (signature.Verifier, error) {
pub, err := cryptoutils.UnmarshalPEMToPublicKey(raw)
if err != nil {
return nil, err
}
return signature.LoadVerifier(pub, hashAlgorithm)
opts := *cosign.GetDefaultLoadOptions(defaultLoadOptions)
opts = append(opts, options.WithHash(hashAlgorithm))
return signature.LoadVerifierWithOpts(pub, opts...)
}

func SignerFromKeyRef(ctx context.Context, keyRef string, pf cosign.PassFunc) (signature.Signer, error) {
Expand Down Expand Up @@ -169,18 +174,18 @@ func SignerVerifierFromKeyRef(ctx context.Context, keyRef string, pf cosign.Pass
}

func PublicKeyFromKeyRef(ctx context.Context, keyRef string) (signature.Verifier, error) {
return PublicKeyFromKeyRefWithHashAlgo(ctx, keyRef, crypto.SHA256)
return PublicKeyFromKeyRefWithHashAlgo(ctx, keyRef, crypto.SHA256, nil)
}

func PublicKeyFromKeyRefWithHashAlgo(ctx context.Context, keyRef string, hashAlgorithm crypto.Hash) (signature.Verifier, error) {
func PublicKeyFromKeyRefWithHashAlgo(ctx context.Context, keyRef string, hashAlgorithm crypto.Hash, defaultLoadOptions *[]signature.LoadOption) (signature.Verifier, error) {
if strings.HasPrefix(keyRef, kubernetes.KeyReference) {
s, err := kubernetes.GetKeyPairSecret(ctx, keyRef)
if err != nil {
return nil, err
}

if len(s.Data) > 0 {
return LoadPublicKeyRaw(s.Data["cosign.pub"], hashAlgorithm)
return LoadPublicKeyRaw(s.Data["cosign.pub"], hashAlgorithm, defaultLoadOptions)
}
}

Expand Down Expand Up @@ -219,11 +224,11 @@ func PublicKeyFromKeyRefWithHashAlgo(ctx context.Context, keyRef string, hashAlg
}

if len(pubKey) > 0 {
return LoadPublicKeyRaw([]byte(pubKey), hashAlgorithm)
return LoadPublicKeyRaw([]byte(pubKey), hashAlgorithm, defaultLoadOptions)
}
}

return VerifierForKeyRef(ctx, keyRef, hashAlgorithm)
return VerifierForKeyRef(ctx, keyRef, hashAlgorithm, defaultLoadOptions)
}

func PublicKeyPem(key signature.PublicKeyProvider, pkOpts ...signature.PublicKeyOption) ([]byte, error) {
Expand Down
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