go/common/crypto/signature/signers/remote: Initial import

.changelog/2686.feature.md

@@ -0,0 +1,5 @@
+go/common/crypto/signature/signers/remote: Add experimental remote signer
+
+This commit adds an experimental remote signer, reference remote signer
+implementation, and allows the node to be ran with a non-file based signer
+backend.

go/.gitignore

@@ -5,4 +5,5 @@ oasis-node/oasis-node
 oasis-node/integrationrunner/integrationrunner.test
 oasis-test-runner/oasis-test-runner
 oasis-net-runner/oasis-net-runner
+oasis-remote-signer/oasis-remote-signer
 storage/mkvs/urkel/interop/urkel-test-helpers

go/Makefile

@@ -10,7 +10,7 @@ all: build
 
 # Build.
 # List of Go binaries to build.
-go-binaries := oasis-node oasis-test-runner oasis-net-runner extra/stats
+go-binaries := oasis-node oasis-test-runner oasis-net-runner oasis-remote-signer extra/stats
 # List of test helpers to build.
 test-helpers := urkel
 # List of test vectors to generate.

go/common/crypto/signature/signer.go

@@ -36,10 +36,19 @@ var (
 	errUnregisteredContext = errors.New("signature: unregistered context")
 	errNoChainContext      = errors.New("signature: chain domain separation context not set")
 
-	registeredContexts sync.Map
+	registeredContexts        sync.Map
+	allowUnregisteredContexts bool
 
 	chainContextLock sync.RWMutex
 	chainContext     Context
+
+	// SignerRoles is the list of all supported signer roles.
+	SignerRoles = []SignerRole{
+		SignerEntity,
+		SignerNode,
+		SignerP2P,
+		SignerConsensus,
+	}
 )
 
 type contextOptions struct {
@@ -111,6 +120,13 @@ func UnsafeResetChainContext() {
 	chainContext = Context("")
 }
 
+// UnsafeAllowUnregisteredContexts bypasses the context registration check.
+//
+// This function is only for the benefit of implementing a remote signer.
+func UnsafeAllowUnregisteredContexts() {
+	allowUnregisteredContexts = true
+}
+
 // SetChainContext configures the chain domain separation context that is
 // used with any contexts constructed using the WithChainSeparation option.
 func SetChainContext(rawContext string) {
@@ -137,10 +153,12 @@ const (
 	SignerNode
 	SignerP2P
 	SignerConsensus
+
+	// If you add to this, also add the new roles to SignerRoles.
 )
 
 // SignerFactoryCtor is an SignerFactory constructor.
-type SignerFactoryCtor func(interface{}, ...SignerRole) SignerFactory
+type SignerFactoryCtor func(interface{}, ...SignerRole) (SignerFactory, error)
 
 // SignerFactory is the opaque factory interface for Signers.
 type SignerFactory interface {
@@ -187,6 +205,17 @@ type UnsafeSigner interface {
 
 // PrepareSignerContext prepares a context for use during signing by a Signer.
 func PrepareSignerContext(context Context) ([]byte, error) {
+	// The remote signer implementation uses the raw context, and
+	// registration is dealt with client side.  Just check that the
+	// length is sensible, even though the client should be sending
+	// something sane.
+	if allowUnregisteredContexts {
+		if cLen := len(context); cLen == 0 || cLen > ed25519.ContextMaxSize {
+			return nil, errMalformedContext
+		}
+		return []byte(context), nil
+	}
+
 	// Ensure that the context is registered for use.
 	rawOpts, isRegistered := registeredContexts.Load(context)
 	if !isRegistered {

go/common/crypto/signature/signers/file/file_signer.go

@@ -47,16 +47,16 @@ var (
 
 // NewFactory creates a new factory with the specified roles, with the
 // specified dataDir.
-func NewFactory(config interface{}, roles ...signature.SignerRole) signature.SignerFactory {
+func NewFactory(config interface{}, roles ...signature.SignerRole) (signature.SignerFactory, error) {
 	dataDir, ok := config.(string)
 	if !ok {
-		panic("invalid file signer configuration provided")
+		return nil, errors.New("signature/signer/file: invalid file signer configuration provided")
 	}
 
 	return &Factory{
 		roles:   append([]signature.SignerRole{}, roles...),
 		dataDir: dataDir,
-	}
+	}, nil
 }
 
 // Factory is a PEM file backed SignerFactory.

go/common/crypto/signature/signers/file/file_signer_test.go

@@ -22,7 +22,8 @@ func TestFileSigner(t *testing.T) {
 	defer os.RemoveAll(tmpDir)
 
 	rolePEMFiles[signature.SignerUnknown] = "unit_test.pem"
-	factory := NewFactory(tmpDir, signature.SignerUnknown)
+	factory, err := NewFactory(tmpDir, signature.SignerUnknown)
+	require.NoError(err, "NewFactory()")
 
 	// Missing, no generate.
 	_, err = factory.Load(signature.SignerUnknown)

go/common/crypto/signature/signers/ledger/ledger_signer.go

@@ -49,16 +49,16 @@ type FactoryConfig struct {
 }
 
 // NewFactory creates a new factory with the specified roles.
-func NewFactory(config interface{}, roles ...signature.SignerRole) signature.SignerFactory {
+func NewFactory(config interface{}, roles ...signature.SignerRole) (signature.SignerFactory, error) {
 	ledgerConfig, ok := config.(*FactoryConfig)
 	if !ok {
-		panic("invalid Ledger signer configuration provided")
+		return nil, fmt.Errorf("invalid Ledger signer configuration provided")
 	}
 	return &Factory{
 		roles:   append([]signature.SignerRole{}, roles...),
 		address: ledgerConfig.Address,
 		index:   ledgerConfig.Index,
-	}
+	}, nil
 }
 
 // EnsureRole ensures that the SignatureFactory is configured for the given