Initial project snapshot

agents/rap-node-agent/internal/authority/authority.go

@@ -0,0 +1,110 @@
+package authority
+
+import (
+	"crypto/ed25519"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+)
+
+const (
+	AuthoritySchemaVersion = "rap.cluster_authority.v1"
+	SignatureSchemaVersion = "rap.cluster_authority.signature.v1"
+	AlgorithmEd25519       = "ed25519"
+)
+
+var (
+	ErrInvalidKey       = errors.New("invalid cluster authority key")
+	ErrInvalidSignature = errors.New("invalid cluster authority signature")
+	ErrInvalidPayload   = errors.New("invalid cluster authority payload")
+)
+
+type Signature struct {
+	SchemaVersion  string `json:"schema_version"`
+	Algorithm      string `json:"algorithm"`
+	KeyFingerprint string `json:"key_fingerprint"`
+	Signature      string `json:"signature"`
+}
+
+func VerifyRaw(publicKeyB64 string, payload json.RawMessage, signature Signature) error {
+	if signature.SchemaVersion != SignatureSchemaVersion {
+		return fmt.Errorf("%w: schema_version must be %s", ErrInvalidSignature, SignatureSchemaVersion)
+	}
+	if signature.Algorithm != AlgorithmEd25519 {
+		return fmt.Errorf("%w: algorithm must be %s", ErrInvalidSignature, AlgorithmEd25519)
+	}
+	publicKey, err := decodePublicKey(publicKeyB64)
+	if err != nil {
+		return err
+	}
+	if signature.KeyFingerprint != Fingerprint(publicKey) {
+		return fmt.Errorf("%w: key fingerprint mismatch", ErrInvalidSignature)
+	}
+	canonical, err := CanonicalJSON(payload)
+	if err != nil {
+		return err
+	}
+	decodedSignature, err := decodeBase64(strings.TrimSpace(signature.Signature))
+	if err != nil || len(decodedSignature) != ed25519.SignatureSize {
+		return fmt.Errorf("%w: signature must be base64 ed25519 signature", ErrInvalidSignature)
+	}
+	if !ed25519.Verify(publicKey, canonical, decodedSignature) {
+		return ErrInvalidSignature
+	}
+	return nil
+}
+
+func Fingerprint(publicKey ed25519.PublicKey) string {
+	sum := sha256.Sum256(publicKey)
+	return "rap-ca-ed25519-" + hex.EncodeToString(sum[:16])
+}
+
+func HashRaw(raw json.RawMessage) (string, error) {
+	canonical, err := CanonicalJSON(raw)
+	if err != nil {
+		return "", err
+	}
+	sum := sha256.Sum256(canonical)
+	return hex.EncodeToString(sum[:]), nil
+}
+
+func CanonicalJSON(raw json.RawMessage) ([]byte, error) {
+	if len(raw) == 0 {
+		return nil, fmt.Errorf("%w: empty payload", ErrInvalidPayload)
+	}
+	var value any
+	if err := json.Unmarshal(raw, &value); err != nil {
+		return nil, fmt.Errorf("%w: invalid json: %v", ErrInvalidPayload, err)
+	}
+	canonical, err := json.Marshal(value)
+	if err != nil {
+		return nil, fmt.Errorf("%w: canonical json: %v", ErrInvalidPayload, err)
+	}
+	return canonical, nil
+}
+
+func decodePublicKey(value string) (ed25519.PublicKey, error) {
+	decoded, err := decodeBase64(strings.TrimSpace(value))
+	if err != nil {
+		return nil, fmt.Errorf("%w: public key must be base64 encoded", ErrInvalidKey)
+	}
+	if len(decoded) != ed25519.PublicKeySize {
+		return nil, fmt.Errorf("%w: public key must decode to %d bytes", ErrInvalidKey, ed25519.PublicKeySize)
+	}
+	return ed25519.PublicKey(decoded), nil
+}
+
+func decodeBase64(value string) ([]byte, error) {
+	if value == "" {
+		return nil, errors.New("empty base64 value")
+	}
+	decoded, err := base64.StdEncoding.DecodeString(value)
+	if err == nil {
+		return decoded, nil
+	}
+	return base64.RawStdEncoding.DecodeString(value)
+}

agents/rap-node-agent/internal/authority/authority_test.go

@@ -0,0 +1,52 @@
+package authority
+
+import (
+	"crypto/ed25519"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"testing"
+)
+
+func TestVerifyRawAcceptsSignedPayload(t *testing.T) {
+	publicKey, privateKey, err := ed25519.GenerateKey(nil)
+	if err != nil {
+		t.Fatalf("GenerateKey: %v", err)
+	}
+	payload := json.RawMessage(`{"cluster_id":"cluster-1","schema_version":"test.v1"}`)
+	canonical, err := CanonicalJSON(payload)
+	if err != nil {
+		t.Fatalf("CanonicalJSON: %v", err)
+	}
+	signature := Signature{
+		SchemaVersion:  SignatureSchemaVersion,
+		Algorithm:      AlgorithmEd25519,
+		KeyFingerprint: Fingerprint(publicKey),
+		Signature:      base64.StdEncoding.EncodeToString(ed25519.Sign(privateKey, canonical)),
+	}
+	if err := VerifyRaw(base64.StdEncoding.EncodeToString(publicKey), payload, signature); err != nil {
+		t.Fatalf("VerifyRaw: %v", err)
+	}
+}
+
+func TestVerifyRawRejectsTamperedPayload(t *testing.T) {
+	publicKey, privateKey, err := ed25519.GenerateKey(nil)
+	if err != nil {
+		t.Fatalf("GenerateKey: %v", err)
+	}
+	payload := json.RawMessage(`{"cluster_id":"cluster-1","schema_version":"test.v1"}`)
+	canonical, err := CanonicalJSON(payload)
+	if err != nil {
+		t.Fatalf("CanonicalJSON: %v", err)
+	}
+	signature := Signature{
+		SchemaVersion:  SignatureSchemaVersion,
+		Algorithm:      AlgorithmEd25519,
+		KeyFingerprint: Fingerprint(publicKey),
+		Signature:      base64.StdEncoding.EncodeToString(ed25519.Sign(privateKey, canonical)),
+	}
+	tampered := json.RawMessage(`{"cluster_id":"cluster-2","schema_version":"test.v1"}`)
+	if err := VerifyRaw(base64.StdEncoding.EncodeToString(publicKey), tampered, signature); !errors.Is(err, ErrInvalidSignature) {
+		t.Fatalf("err = %v, want ErrInvalidSignature", err)
+	}
+}