feat: protect postbox message content

src/govoplan_postbox/backend/db/models.py

@@ -11,6 +11,7 @@ from sqlalchemy import (
     Index,
     Integer,
     JSON,
+    LargeBinary,
     String,
     Text,
     UniqueConstraint,
@@ -145,6 +146,9 @@ class PostboxTemplateRevision(Base, TimestampMixin):
         default="plaintext_v1",
         nullable=False,
     )
+    encryption_vault_id: Mapped[str | None] = mapped_column(
+        String(255), nullable=True
+    )
     history_policy: Mapped[dict[str, Any]] = mapped_column(
         JSON,
         default=dict,
@@ -420,6 +424,9 @@ class PostboxMessage(Base, TimestampMixin):
     )
     subject: Mapped[str] = mapped_column(String(1000), nullable=False)
     body_text: Mapped[str | None] = mapped_column(Text, nullable=True)
+    body_ciphertext: Mapped[bytes | None] = mapped_column(
+        LargeBinary, nullable=True
+    )
     status: Mapped[str] = mapped_column(
         String(30),
         default="delivered",
@@ -473,6 +480,12 @@ class PostboxMessage(Base, TimestampMixin):
         String(1000),
         nullable=True,
     )
+    encryption_envelope_id: Mapped[str | None] = mapped_column(
+        String(255), nullable=True, index=True
+    )
+    encryption_resource_id: Mapped[str | None] = mapped_column(
+        String(36), nullable=True, index=True
+    )
     signed_manifest_ref: Mapped[str | None] = mapped_column(
         String(1000),
         nullable=True,