signature: add OpenPGP signing mechanism based on Sequoia

go.mod

@@ -127,6 +127,7 @@ require (
 	github.com/syndtr/gocapability v0.0.0-20200815063812-42c35b437635 // indirect
 	github.com/tchap/go-patricia/v2 v2.3.1 // indirect
 	github.com/titanous/rocacheck v0.0.0-20171023193734-afe73141d399 // indirect
+	github.com/ueno/podman-sequoia/go v0.0.0-20240917014836-c53d571fb375 // indirect
 	github.com/xeipuuv/gojsonpointer v0.0.0-20190905194746-02993c407bfb // indirect
 	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
 	go.mongodb.org/mongo-driver v1.14.0 // indirect

go.sum

@@ -335,6 +335,8 @@ github.com/tchap/go-patricia/v2 v2.3.1 h1:6rQp39lgIYZ+MHmdEq4xzuk1t7OdC35z/xm0BG
 github.com/tchap/go-patricia/v2 v2.3.1/go.mod h1:VZRHKAb53DLaG+nA9EaYYiaEx6YztwDlLElMsnSHD4k=
 github.com/titanous/rocacheck v0.0.0-20171023193734-afe73141d399 h1:e/5i7d4oYZ+C1wj2THlRK+oAhjeS/TRQwMfkIuet3w0=
 github.com/titanous/rocacheck v0.0.0-20171023193734-afe73141d399/go.mod h1:LdwHTNJT99C5fTAzDz0ud328OgXz+gierycbcIx2fRs=
+github.com/ueno/podman-sequoia/go v0.0.0-20240917014836-c53d571fb375 h1:k6F/0KdIf86gLWN2WWJkA9Dz+yD24y7k+QZlLKUOHEU=
+github.com/ueno/podman-sequoia/go v0.0.0-20240917014836-c53d571fb375/go.mod h1:rL7oFaeDd+3z0KyQI+GTz3ZE0ZvO4mT2+zMAXxZiPvM=
 github.com/ulikunitz/xz v0.5.12 h1:37Nm15o69RwBkXM0J6A5OlE67RZTfzUxTj8fB3dfcsc=
 github.com/ulikunitz/xz v0.5.12/go.mod h1:nbz6k7qbPmH4IRqmfOplQw/tblSgqTqBwxkY0oWt/14=
 github.com/vbatts/tar-split v0.11.5 h1:3bHCTIheBm1qFTcgh9oPu+nNBtX+XJIupG/vacinCts=

signature/mechanism_gpgme.go

@@ -1,5 +1,5 @@
-//go:build !containers_image_openpgp
-// +build !containers_image_openpgp
+//go:build !containers_image_openpgp && !containers_image_sequoia
+// +build !containers_image_openpgp,!containers_image_sequoia
 
 package signature
 

signature/mechanism_gpgme_test.go

@@ -1,5 +1,5 @@
-//go:build !containers_image_openpgp
-// +build !containers_image_openpgp
+//go:build !containers_image_openpgp && !containers_image_sequoia
+// +build !containers_image_openpgp,!containers_image_sequoia
 
 package signature
 

signature/mechanism_sequoia.go

@@ -0,0 +1,131 @@
+//go:build containers_image_sequoia
+// +build containers_image_sequoia
+
+package signature
+
+import (
+	"github.com/containers/storage/pkg/homedir"
+	"github.com/ueno/podman-sequoia/go/sequoia"
+	"os"
+	"path"
+)
+
+// A GPG/OpenPGP signing mechanism, implemented using Sequoia.
+type sequoiaSigningMechanism struct {
+	inner *sequoia.SigningMechanism
+}
+
+// newGPGSigningMechanismInDirectory returns a new GPG/OpenPGP signing mechanism, using optionalDir if not empty.
+// The caller must call .Close() on the returned SigningMechanism.
+func newGPGSigningMechanismInDirectory(optionalDir string) (signingMechanismWithPassphrase, error) {
+	// For compatibility reasons, we allow both sequoiaHome and
+	// gpgHome to be the same directory as designated by
+	// optionalDir or GNUPGHOME.
+	envHome := os.Getenv("GNUPGHOME")
+
+	gpgHome := optionalDir
+	if gpgHome == "" {
+		gpgHome = envHome
+		if gpgHome == "" {
+			gpgHome = path.Join(homedir.Get(), ".gnupg")
+		}
+	}
+
+	sequoiaHome := optionalDir
+	if sequoiaHome == "" {
+		sequoiaHome = envHome
+		if sequoiaHome == "" {
+			dataHome, err := homedir.GetDataHome()
+			if err != nil {
+				return nil, err
+			}
+			sequoiaHome = path.Join(dataHome, "sequoia")
+		}
+	}
+
+	mech, err := sequoia.NewMechanismFromDirectory(sequoiaHome)
+	if err != nil {
+		return nil, err
+	}
+
+	// Migrate GnuPG keyrings if exist.
+	for _, keyring := range []string{"pubring.gpg", "secring.gpg"} {
+		blob, err := os.ReadFile(path.Join(gpgHome, keyring))
+		if err != nil {
+			if !os.IsNotExist(err) {
+				return nil, err
+			}
+		} else if _, err := mech.ImportKeys(blob); err != nil {
+			return nil, err
+		}
+	}
+
+	return &sequoiaSigningMechanism{
+		inner: mech,
+	}, nil
+}
+
+// newEphemeralGPGSigningMechanism returns a new GPG/OpenPGP signing mechanism which
+// recognizes _only_ public keys from the supplied blobs, and returns the identities
+// of these keys.
+// The caller must call .Close() on the returned SigningMechanism.
+func newEphemeralGPGSigningMechanism(blobs [][]byte) (signingMechanismWithPassphrase, []string, error) {
+	mech, err := sequoia.NewEphemeralMechanism()
+	if err != nil {
+		return nil, nil, err
+	}
+	keyIdentities := []string{}
+	for _, blob := range blobs {
+		ki, err := mech.ImportKeys(blob)
+		if err != nil {
+			return nil, nil, err
+		}
+		keyIdentities = append(keyIdentities, ki...)
+	}
+
+	return &sequoiaSigningMechanism{
+		inner: mech,
+	}, keyIdentities, nil
+}
+
+func (m *sequoiaSigningMechanism) Close() error {
+	return m.inner.Close()
+}
+
+// SupportsSigning returns nil if the mechanism supports signing, or a SigningNotSupportedError.
+func (m *sequoiaSigningMechanism) SupportsSigning() error {
+	return m.inner.SupportsSigning()
+}
+
+// Sign creates a (non-detached) signature of input using keyIdentity and passphrase.
+// Fails with a SigningNotSupportedError if the mechanism does not support signing.
+func (m *sequoiaSigningMechanism) SignWithPassphrase(input []byte, keyIdentity string, passphrase string) ([]byte, error) {
+	return m.inner.SignWithPassphrase(input, keyIdentity, passphrase)
+}
+
+// Sign creates a (non-detached) signature of input using keyIdentity.
+// Fails with a SigningNotSupportedError if the mechanism does not support signing.
+func (m *sequoiaSigningMechanism) Sign(input []byte, keyIdentity string) ([]byte, error) {
+	return m.inner.Sign(input, keyIdentity)
+}
+
+// Verify parses unverifiedSignature and returns the content and the signer's identity
+func (m *sequoiaSigningMechanism) Verify(unverifiedSignature []byte) (contents []byte, keyIdentity string, err error) {
+	return m.inner.Verify(unverifiedSignature)
+}
+
+// UntrustedSignatureContents returns UNTRUSTED contents of the signature WITHOUT ANY VERIFICATION,
+// along with a short identifier of the key used for signing.
+// WARNING: The short key identifier (which corresponds to "Key ID" for OpenPGP keys)
+// is NOT the same as a "key identity" used in other calls to this interface, and
+// the values may have no recognizable relationship if the public key is not available.
+func (m *sequoiaSigningMechanism) UntrustedSignatureContents(untrustedSignature []byte) (untrustedContents []byte, shortKeyIdentifier string, err error) {
+	return gpgUntrustedSignatureContents(untrustedSignature)
+}
+
+func init() {
+	err := sequoia.Init()
+	if err != nil {
+		panic("sequoia cannot be loaded: " + err.Error())
+	}
+}

signature/mechanism_test.go

@@ -1,6 +1,6 @@
 package signature
 
-// These tests are expected to pass unmodified for _both_ mechanism_gpgme.go and mechanism_openpgp.go.
+// These tests are expected to pass unmodified for _all_ mechanism_sequoia.go, mechanism_gpgme.go, and mechanism_openpgp.go.
 
 import (
 	"bytes"