refactor: Decompose archive func

internal/encryption/decrypt.go

@@ -46,7 +46,7 @@ func Decrypt(
 	case config.NoneKey:
 		return io.NopCloser(src), nil
 	default:
-		return nil, config.ErrUnsupportedEncryptionFormat
+		return nil, config.ErrEncryptionFormatUnsupported
 	}
 }
 
@@ -136,6 +136,6 @@ func DecryptString(
 	case config.NoneKey:
 		return src, nil
 	default:
-		return "", config.ErrUnsupportedEncryptionFormat
+		return "", config.ErrEncryptionFormatUnsupported
 	}
 }

internal/encryption/encrypt.go

@@ -0,0 +1,127 @@
+package encryption
+
+import (
+	"archive/tar"
+	"bytes"
+	"encoding/base64"
+	"encoding/json"
+	"io"
+
+	"filippo.io/age"
+	"github.com/pojntfx/stfs/internal/noop"
+	"github.com/pojntfx/stfs/internal/pax"
+	"github.com/pojntfx/stfs/pkg/config"
+	"golang.org/x/crypto/openpgp"
+)
+
+func Encrypt(
+	dst io.Writer,
+	encryptionFormat string,
+	recipient interface{},
+) (io.WriteCloser, error) {
+	switch encryptionFormat {
+	case config.EncryptionFormatAgeKey:
+		recipient, ok := recipient.(*age.X25519Recipient)
+		if !ok {
+			return nil, config.ErrRecipientUnparsable
+		}
+
+		return age.Encrypt(dst, recipient)
+	case config.EncryptionFormatPGPKey:
+		recipient, ok := recipient.(openpgp.EntityList)
+		if !ok {
+			return nil, config.ErrRecipientUnparsable
+		}
+
+		return openpgp.Encrypt(dst, recipient, nil, nil, nil)
+	case config.NoneKey:
+		return noop.AddClose(dst), nil
+	default:
+		return nil, config.ErrEncryptionFormatUnsupported
+	}
+}
+
+func EncryptHeader(
+	hdr *tar.Header,
+	encryptionFormat string,
+	recipient interface{},
+) error {
+	if encryptionFormat == config.NoneKey {
+		return nil
+	}
+
+	newHdr := &tar.Header{
+		Format:     tar.FormatPAX,
+		Size:       hdr.Size,
+		PAXRecords: map[string]string{},
+	}
+
+	wrappedHeader, err := json.Marshal(hdr)
+	if err != nil {
+		return err
+	}
+
+	newHdr.PAXRecords[pax.STFSRecordEmbeddedHeader], err = EncryptString(string(wrappedHeader), encryptionFormat, recipient)
+	if err != nil {
+		return err
+	}
+
+	*hdr = *newHdr
+
+	return nil
+}
+
+func EncryptString(
+	src string,
+	encryptionFormat string,
+	recipient interface{},
+) (string, error) {
+	switch encryptionFormat {
+	case config.EncryptionFormatAgeKey:
+		recipient, ok := recipient.(*age.X25519Recipient)
+		if !ok {
+			return "", config.ErrRecipientUnparsable
+		}
+
+		out := &bytes.Buffer{}
+		w, err := age.Encrypt(out, recipient)
+		if err != nil {
+			return "", err
+		}
+
+		if _, err := io.WriteString(w, src); err != nil {
+			return "", err
+		}
+
+		if err := w.Close(); err != nil {
+			return "", err
+		}
+
+		return base64.StdEncoding.EncodeToString(out.Bytes()), nil
+	case config.EncryptionFormatPGPKey:
+		recipient, ok := recipient.(openpgp.EntityList)
+		if !ok {
+			return "", config.ErrRecipientUnparsable
+		}
+
+		out := &bytes.Buffer{}
+		w, err := openpgp.Encrypt(out, recipient, nil, nil, nil)
+		if err != nil {
+			return "", err
+		}
+
+		if _, err := io.WriteString(w, src); err != nil {
+			return "", err
+		}
+
+		if err := w.Close(); err != nil {
+			return "", err
+		}
+
+		return base64.StdEncoding.EncodeToString(out.Bytes()), nil
+	case config.NoneKey:
+		return src, nil
+	default:
+		return "", config.ErrEncryptionFormatUnsupported
+	}
+}