diff --git a/app/database.py b/app/database.py
index 42436a3..0c25ce4 100644
--- a/app/database.py
+++ b/app/database.py
@@ -58,7 +58,7 @@ CREATE TABLE IF NOT EXISTS raw_packets (
     timestamp INTEGER NOT NULL,
     data BLOB NOT NULL,
     message_id INTEGER,
-    payload_hash TEXT,
+    payload_hash BLOB,
     FOREIGN KEY (message_id) REFERENCES messages(id)
 );
 
diff --git a/app/migrations.py b/app/migrations.py
index 6fa0240..27b08e8 100644
--- a/app/migrations.py
+++ b/app/migrations.py
@@ -226,6 +226,13 @@ async def run_migrations(conn: aiosqlite.Connection) -> int:
         await set_version(conn, 27)
         applied += 1
 
+    # Migration 28: Convert payload_hash from 64-char hex TEXT to 32-byte BLOB
+    if version < 28:
+        logger.info("Applying migration 28: convert payload_hash from TEXT to BLOB")
+        await _migrate_028_payload_hash_text_to_blob(conn)
+        await set_version(conn, 28)
+        applied += 1
+
     if applied > 0:
         logger.info(
             "Applied %d migration(s), schema now at version %d", applied, await get_version(conn)
@@ -1682,3 +1689,104 @@ async def _migrate_027_backfill_first_seen_from_advert_paths(conn: aiosqlite.Con
 
     await conn.commit()
     logger.debug("Backfilled first_seen from contact_advert_paths")
+
+
+async def _migrate_028_payload_hash_text_to_blob(conn: aiosqlite.Connection) -> None:
+    """
+    Convert payload_hash from 64-char hex TEXT to 32-byte BLOB.
+
+    Halves storage for both the column data and its UNIQUE index.
+    Uses Python bytes.fromhex() for the conversion since SQLite's unhex()
+    requires 3.41.0+ which may not be available on all deployments.
+    """
+    # Guard: skip if raw_packets table doesn't exist
+    cursor = await conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table' AND name='raw_packets'"
+    )
+    if not await cursor.fetchone():
+        logger.debug("raw_packets table does not exist, skipping payload_hash conversion")
+        await conn.commit()
+        return
+
+    # Check column types — skip if payload_hash doesn't exist or is already BLOB
+    cursor = await conn.execute("PRAGMA table_info(raw_packets)")
+    cols = {row[1]: row[2] for row in await cursor.fetchall()}
+    if "payload_hash" not in cols:
+        logger.debug("payload_hash column does not exist, skipping conversion")
+        await conn.commit()
+        return
+    if cols["payload_hash"].upper() == "BLOB":
+        logger.debug("payload_hash is already BLOB, skipping conversion")
+        await conn.commit()
+        return
+
+    logger.info("Rebuilding raw_packets to convert payload_hash TEXT → BLOB...")
+
+    # Create new table with BLOB type
+    await conn.execute("""
+        CREATE TABLE raw_packets_new (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            timestamp INTEGER NOT NULL,
+            data BLOB NOT NULL,
+            message_id INTEGER,
+            payload_hash BLOB,
+            FOREIGN KEY (message_id) REFERENCES messages(id)
+        )
+    """)
+
+    # Batch-convert rows: read TEXT hashes, convert to bytes, insert into new table
+    batch_size = 5000
+    cursor = await conn.execute(
+        "SELECT id, timestamp, data, message_id, payload_hash FROM raw_packets ORDER BY id"
+    )
+
+    total = 0
+    while True:
+        rows = await cursor.fetchmany(batch_size)
+        if not rows:
+            break
+
+        batch: list[tuple[int, int, bytes, int | None, bytes | None]] = []
+        for row in rows:
+            rid, ts, data, mid, ph = row[0], row[1], row[2], row[3], row[4]
+            if ph is not None and isinstance(ph, str):
+                try:
+                    ph = bytes.fromhex(ph)
+                except ValueError:
+                    # Not a valid hex string — hash the value to produce a valid BLOB
+                    ph = sha256(ph.encode()).digest()
+            batch.append((rid, ts, data, mid, ph))
+
+        await conn.executemany(
+            "INSERT INTO raw_packets_new (id, timestamp, data, message_id, payload_hash) "
+            "VALUES (?, ?, ?, ?, ?)",
+            batch,
+        )
+        total += len(batch)
+
+        if total % 50000 == 0:
+            logger.info("Converted %d rows...", total)
+
+    # Preserve autoincrement sequence
+    cursor = await conn.execute("SELECT seq FROM sqlite_sequence WHERE name = 'raw_packets'")
+    seq_row = await cursor.fetchone()
+    if seq_row is not None:
+        await conn.execute(
+            "INSERT OR REPLACE INTO sqlite_sequence (name, seq) VALUES ('raw_packets_new', ?)",
+            (seq_row[0],),
+        )
+
+    await conn.execute("DROP TABLE raw_packets")
+    await conn.execute("ALTER TABLE raw_packets_new RENAME TO raw_packets")
+
+    # Clean up the sqlite_sequence entry for the old temp name
+    await conn.execute("DELETE FROM sqlite_sequence WHERE name = 'raw_packets_new'")
+
+    # Recreate indexes
+    await conn.execute(
+        "CREATE UNIQUE INDEX idx_raw_packets_payload_hash ON raw_packets(payload_hash)"
+    )
+    await conn.execute("CREATE INDEX idx_raw_packets_message_id ON raw_packets(message_id)")
+
+    await conn.commit()
+    logger.info("Converted %d payload_hash values from TEXT to BLOB", total)
diff --git a/app/repository.py b/app/repository.py
index e4511b4..170c5dd 100644
--- a/app/repository.py
+++ b/app/repository.py
@@ -935,10 +935,10 @@ class RawPacketRepository:
         # Compute payload hash for deduplication
         payload = extract_payload(data)
         if payload:
-            payload_hash = sha256(payload).hexdigest()
+            payload_hash = sha256(payload).digest()
         else:
             # For malformed packets, hash the full data
-            payload_hash = sha256(data).hexdigest()
+            payload_hash = sha256(data).digest()
 
         # Check if this payload already exists
         cursor = await db.conn.execute(
@@ -950,7 +950,7 @@ class RawPacketRepository:
             # Duplicate - return existing packet ID
             logger.debug(
                 "Duplicate payload detected (hash=%s..., existing_id=%d)",
-                payload_hash[:12],
+                payload_hash.hex()[:12],
                 existing["id"],
             )
             return (existing["id"], False)
@@ -970,7 +970,7 @@ class RawPacketRepository:
             # close together. Query again to get the existing ID.
             logger.debug(
                 "Duplicate packet detected via race condition (payload_hash=%s), dropping",
-                payload_hash[:16],
+                payload_hash.hex()[:16],
             )
             cursor = await db.conn.execute(
                 "SELECT id FROM raw_packets WHERE payload_hash = ?", (payload_hash,)
diff --git a/tests/test_migrations.py b/tests/test_migrations.py
index 7b1cd9a..95c9fa1 100644
--- a/tests/test_migrations.py
+++ b/tests/test_migrations.py
@@ -100,8 +100,8 @@ class TestMigration001:
             # Run migrations
             applied = await run_migrations(conn)
 
-            assert applied == 27  # All migrations run
-            assert await get_version(conn) == 27
+            assert applied == 28  # All migrations run
+            assert await get_version(conn) == 28
 
             # Verify columns exist by inserting and selecting
             await conn.execute(
@@ -183,9 +183,9 @@ class TestMigration001:
             applied1 = await run_migrations(conn)
             applied2 = await run_migrations(conn)
 
-            assert applied1 == 27  # All migrations run
+            assert applied1 == 28  # All migrations run
             assert applied2 == 0  # No migrations on second run
-            assert await get_version(conn) == 27
+            assert await get_version(conn) == 28
         finally:
             await conn.close()
 
@@ -246,8 +246,8 @@ class TestMigration001:
             applied = await run_migrations(conn)
 
             # All migrations applied (version incremented) but no error
-            assert applied == 27
-            assert await get_version(conn) == 27
+            assert applied == 28
+            assert await get_version(conn) == 28
         finally:
             await conn.close()
 
@@ -376,8 +376,8 @@ class TestMigration013:
 
             # Run migration 13 (plus 14-27 which also run)
             applied = await run_migrations(conn)
-            assert applied == 15
-            assert await get_version(conn) == 27
+            assert applied == 16
+            assert await get_version(conn) == 28
 
             # Verify bots array was created with migrated data
             cursor = await conn.execute("SELECT bots FROM app_settings WHERE id = 1")
@@ -497,7 +497,7 @@ class TestMigration018:
             assert await cursor.fetchone() is not None
 
             await run_migrations(conn)
-            assert await get_version(conn) == 27
+            assert await get_version(conn) == 28
 
             # Verify autoindex is gone
             cursor = await conn.execute(
@@ -516,7 +516,11 @@ class TestMigration018:
             assert rows[0]["timestamp"] == 1000
             assert bytes(rows[0]["data"]) == b"\x01\x02\x03"
             assert rows[0]["message_id"] is None
-            assert rows[0]["payload_hash"] == "hash_a"
+            # payload_hash was converted from TEXT to BLOB by migration 28;
+            # "hash_a" is not valid hex so gets sha256-hashed
+            from hashlib import sha256
+
+            assert bytes(rows[0]["payload_hash"]) == sha256(b"hash_a").digest()
             assert rows[1]["message_id"] == 42
 
             # Verify payload_hash unique index still works
@@ -571,8 +575,8 @@ class TestMigration018:
             await conn.commit()
 
             applied = await run_migrations(conn)
-            assert applied == 10  # Migrations 18-27 run (18+19 skip internally)
-            assert await get_version(conn) == 27
+            assert applied == 11  # Migrations 18-28 run (18+19 skip internally)
+            assert await get_version(conn) == 28
         finally:
             await conn.close()
 
@@ -644,7 +648,7 @@ class TestMigration019:
             assert await cursor.fetchone() is not None
 
             await run_migrations(conn)
-            assert await get_version(conn) == 27
+            assert await get_version(conn) == 28
 
             # Verify autoindex is gone
             cursor = await conn.execute(
@@ -710,8 +714,8 @@ class TestMigration020:
             assert (await cursor.fetchone())[0] == "delete"
 
             applied = await run_migrations(conn)
-            assert applied == 8  # Migrations 20-27
-            assert await get_version(conn) == 27
+            assert applied == 9  # Migrations 20-28
+            assert await get_version(conn) == 28
 
             # Verify WAL mode
             cursor = await conn.execute("PRAGMA journal_mode")
@@ -741,7 +745,7 @@ class TestMigration020:
             await set_version(conn, 20)
 
             applied = await run_migrations(conn)
-            assert applied == 7  # Migrations 21-27 still run
+            assert applied == 8  # Migrations 21-28 still run
 
             # Still WAL + INCREMENTAL
             cursor = await conn.execute("PRAGMA journal_mode")
@@ -750,3 +754,131 @@ class TestMigration020:
             assert (await cursor.fetchone())[0] == 2
         finally:
             await conn.close()
+
+
+class TestMigration028:
+    """Test migration 028: convert payload_hash from TEXT to BLOB."""
+
+    @pytest.mark.asyncio
+    async def test_migration_converts_hex_text_to_blob(self):
+        """Migration converts 64-char hex TEXT payload_hash values to 32-byte BLOBs."""
+        from hashlib import sha256
+
+        conn = await aiosqlite.connect(":memory:")
+        conn.row_factory = aiosqlite.Row
+        try:
+            await set_version(conn, 27)
+
+            # Create raw_packets with TEXT payload_hash (pre-migration schema)
+            await conn.execute("""
+                CREATE TABLE raw_packets (
+                    id INTEGER PRIMARY KEY AUTOINCREMENT,
+                    timestamp INTEGER NOT NULL,
+                    data BLOB NOT NULL,
+                    message_id INTEGER,
+                    payload_hash TEXT
+                )
+            """)
+            await conn.execute(
+                "CREATE UNIQUE INDEX idx_raw_packets_payload_hash ON raw_packets(payload_hash)"
+            )
+            await conn.execute("CREATE INDEX idx_raw_packets_message_id ON raw_packets(message_id)")
+
+            # Insert rows with hex TEXT hashes (as produced by .hexdigest())
+            hash_a = sha256(b"packet_a").hexdigest()
+            hash_b = sha256(b"packet_b").hexdigest()
+            await conn.execute(
+                "INSERT INTO raw_packets (timestamp, data, payload_hash) VALUES (?, ?, ?)",
+                (1000, b"\x01\x02", hash_a),
+            )
+            await conn.execute(
+                "INSERT INTO raw_packets (timestamp, data, message_id, payload_hash) VALUES (?, ?, ?, ?)",
+                (2000, b"\x03\x04", 42, hash_b),
+            )
+            # Row with NULL payload_hash
+            await conn.execute(
+                "INSERT INTO raw_packets (timestamp, data) VALUES (?, ?)",
+                (3000, b"\x05\x06"),
+            )
+            await conn.commit()
+
+            applied = await run_migrations(conn)
+            assert applied == 1
+            assert await get_version(conn) == 28
+
+            # Verify payload_hash column is now BLOB
+            cursor = await conn.execute("PRAGMA table_info(raw_packets)")
+            cols = {row[1]: row[2] for row in await cursor.fetchall()}
+            assert cols["payload_hash"] == "BLOB"
+
+            # Verify data is preserved and converted correctly
+            cursor = await conn.execute(
+                "SELECT id, timestamp, data, message_id, payload_hash FROM raw_packets ORDER BY id"
+            )
+            rows = await cursor.fetchall()
+            assert len(rows) == 3
+
+            assert rows[0]["timestamp"] == 1000
+            assert bytes(rows[0]["data"]) == b"\x01\x02"
+            assert bytes(rows[0]["payload_hash"]) == sha256(b"packet_a").digest()
+            assert rows[0]["message_id"] is None
+
+            assert rows[1]["timestamp"] == 2000
+            assert bytes(rows[1]["payload_hash"]) == sha256(b"packet_b").digest()
+            assert rows[1]["message_id"] == 42
+
+            assert rows[2]["payload_hash"] is None
+
+            # Verify unique index works
+            cursor = await conn.execute(
+                "SELECT name FROM sqlite_master WHERE name='idx_raw_packets_payload_hash'"
+            )
+            assert await cursor.fetchone() is not None
+
+            # Verify message_id index exists
+            cursor = await conn.execute(
+                "SELECT name FROM sqlite_master WHERE name='idx_raw_packets_message_id'"
+            )
+            assert await cursor.fetchone() is not None
+        finally:
+            await conn.close()
+
+    @pytest.mark.asyncio
+    async def test_migration_skips_when_already_blob(self):
+        """Migration is a no-op when payload_hash is already BLOB (fresh install)."""
+        conn = await aiosqlite.connect(":memory:")
+        conn.row_factory = aiosqlite.Row
+        try:
+            await set_version(conn, 27)
+
+            # Create raw_packets with BLOB payload_hash (new schema)
+            await conn.execute("""
+                CREATE TABLE raw_packets (
+                    id INTEGER PRIMARY KEY AUTOINCREMENT,
+                    timestamp INTEGER NOT NULL,
+                    data BLOB NOT NULL,
+                    message_id INTEGER,
+                    payload_hash BLOB
+                )
+            """)
+            await conn.execute(
+                "CREATE UNIQUE INDEX idx_raw_packets_payload_hash ON raw_packets(payload_hash)"
+            )
+
+            # Insert a row with a BLOB hash
+            await conn.execute(
+                "INSERT INTO raw_packets (timestamp, data, payload_hash) VALUES (?, ?, ?)",
+                (1000, b"\x01", b"\xab" * 32),
+            )
+            await conn.commit()
+
+            applied = await run_migrations(conn)
+            assert applied == 1  # Version still bumped
+            assert await get_version(conn) == 28
+
+            # Verify data unchanged
+            cursor = await conn.execute("SELECT payload_hash FROM raw_packets")
+            row = await cursor.fetchone()
+            assert bytes(row["payload_hash"]) == b"\xab" * 32
+        finally:
+            await conn.close()
diff --git a/tests/test_statistics.py b/tests/test_statistics.py
index 243f108..cdb2ba1 100644
--- a/tests/test_statistics.py
+++ b/tests/test_statistics.py
@@ -137,15 +137,15 @@ class TestStatisticsCounts:
         # 2 decrypted packets (linked to message), 1 undecrypted
         await conn.execute(
             "INSERT INTO raw_packets (timestamp, data, message_id, payload_hash) VALUES (?, ?, ?, ?)",
-            (now, b"\x01", msg_id, "hash1"),
+            (now, b"\x01", msg_id, b"\x01" * 32),
         )
         await conn.execute(
             "INSERT INTO raw_packets (timestamp, data, message_id, payload_hash) VALUES (?, ?, ?, ?)",
-            (now, b"\x02", msg_id, "hash2"),
+            (now, b"\x02", msg_id, b"\x02" * 32),
         )
         await conn.execute(
             "INSERT INTO raw_packets (timestamp, data, payload_hash) VALUES (?, ?, ?)",
-            (now, b"\x03", "hash3"),
+            (now, b"\x03", b"\x03" * 32),
         )
         await conn.commit()