feat(privacy): strip EXIF/XMP/IPTC from image uploads by default (#109)

Metadata was only dropped as a side effect of opt-in compression, so a
phone photo carried its GPS fix, camera model and timestamp into the room
and the media store. utils/stripImageMetadata.ts now removes it at the
container level, without touching pixels: JPEG drops APP1/APP13/COM
(writing back a minimal EXIF holding only Orientation when it isn't 1,
so sideways-stored photos still display upright), PNG drops eXIf and the
text chunks XMP lives in, WebP drops EXIF/XMP and clears the VP8X flags.
Other types pass through.

Applied before encryption on every composer path (attach, paste, drop,
share target) and to user/room avatar picks; GIF upload is excluded.
Setting → General → Privacy "Remove Photo Metadata Before Sending",
default on. The upload card says "Photo metadata removed".

Unit tests on generated fixtures with a GPS IFD (JPEG orientation 6,
JPEG + comment, PNG with eXIf + XMP, WebP with EXIF); verified end to
end: the bytes stored by Synapse decode fine and carry only Orientation.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/components/upload-card/UploadCardRenderer.tsx

@@ -382,6 +382,14 @@ export function UploadCardRenderer({
             />
           )}
           <CompressionCheckbox fileItem={fileItem} metadata={metadata} setMetadata={setMetadata} />
+          {metadata.metadataStripped && (
+            <Box alignItems="Center" gap="100" style={{ marginTop: config.space.S100 }}>
+              <Icon size="50" src={Icons.Shield} style={{ color: color.Success.Main }} />
+              <Text size="T200" priority="300">
+                Photo metadata removed (location, camera, time)
+              </Text>
+            </Box>
+          )}
           {upload.status === UploadStatus.Idle && !fileSizeExceeded && (
             <UploadCardProgress sentBytes={0} totalBytes={file.size} />
           )}

src/app/features/common-settings/general/RoomProfile.tsx

@@ -43,7 +43,10 @@ import { sendStateEvent } from '../../../utils/room';
 import { CompactUploadCardRenderer } from '../../../components/upload-card';
 import { useObjectURL } from '../../../hooks/useObjectURL';
 import { createUploadAtom, UploadSuccess } from '../../../state/upload';
+import { stripImageMetadata as stripImageMetadata_ } from '../../../utils/stripImageMetadata';
 import { useFilePicker } from '../../../hooks/useFilePicker';
+import { useSetting } from '../../../state/hooks/settings';
+import { settingsAtom } from '../../../state/settings';
 import { AsyncStatus, useAsyncCallback } from '../../../hooks/useAsyncCallback';
 import { useAlive } from '../../../hooks/useAlive';
 import { RoomPermissionsAPI } from '../../../hooks/useRoomPermissions';
@@ -138,7 +141,19 @@ export function RoomProfileEdit({
     return undefined;
   }, [imageFile]);
 
-  const pickFile = useFilePicker(setImageFile, false);
+  // [Gitea #109] Avatars go through the same metadata strip as messages.
+  const [stripImageMetadata] = useSetting(settingsAtom, 'stripImageMetadata');
+  const pickFile = useFilePicker(
+    useCallback(
+      (file: File) => {
+        (stripImageMetadata ? stripImageMetadata_(file) : Promise.resolve({ file })).then((r) =>
+          setImageFile(r.file),
+        );
+      },
+      [stripImageMetadata],
+    ),
+    false,
+  );
 
   const handleRemoveUpload = useCallback(() => {
     setImageFile(undefined);

src/app/features/room/RoomInput.tsx

@@ -279,6 +279,7 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
     const [gifPickerEnabled] = useSetting(settingsAtom, 'gifPickerEnabled');
     // [Gitea #103] Privacy: drop tracking params from links on paste and on send.
     const [stripTracking] = useSetting(settingsAtom, 'stripTrackingParams');
+    const [stripImageMetadata] = useSetting(settingsAtom, 'stripImageMetadata');
     const showGif = (composerToolbarButtons?.showGif ?? true) && gifPickerEnabled;
     const showLocation = composerToolbarButtons?.showLocation ?? true;
     const showPoll = composerToolbarButtons?.showPoll ?? true;
@@ -377,10 +378,10 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
         setUploadBoard(true);
         setSelectedFiles({
           type: 'PUT',
-          item: await filesToUploadItems(room, files),
+          item: await filesToUploadItems(room, files, stripImageMetadata),
         });
       },
-      [setSelectedFiles, room],
+      [setSelectedFiles, room, stripImageMetadata],
     );
     const pickFile = useFilePicker(handleFiles, true);
     const handleFilePaste = useFilePasteHandler(handleFiles);

src/app/features/settings/account/Profile.tsx

@@ -47,6 +47,7 @@ import { UserAvatar } from '../../../components/user-avatar';
 import { useMediaAuthentication } from '../../../hooks/useMediaAuthentication';
 import { nameInitials } from '../../../utils/common';
 import { AsyncStatus, useAsyncCallback } from '../../../hooks/useAsyncCallback';
+import { stripImageMetadata as stripImageMetadata_ } from '../../../utils/stripImageMetadata';
 import { useFilePicker } from '../../../hooks/useFilePicker';
 import { useObjectURL } from '../../../hooks/useObjectURL';
 import { stopPropagation } from '../../../utils/keyboard';
@@ -89,7 +90,19 @@ function ProfileAvatar({ profile, userId }: ProfileProps) {
     return undefined;
   }, [imageFile]);
 
-  const pickFile = useFilePicker(setImageFile, false);
+  // [Gitea #109] Avatars go through the same metadata strip as messages.
+  const [stripImageMetadata] = useSetting(settingsAtom, 'stripImageMetadata');
+  const pickFile = useFilePicker(
+    useCallback(
+      (file: File) => {
+        (stripImageMetadata ? stripImageMetadata_(file) : Promise.resolve({ file })).then((r) =>
+          setImageFile(r.file),
+        );
+      },
+      [stripImageMetadata],
+    ),
+    false,
+  );
 
   const handleRemoveUpload = useCallback(() => {
     setImageFile(undefined);

src/app/features/settings/general/General.tsx

@@ -1442,6 +1442,7 @@ function Privacy() {
     'warnOnUnverifiedDevices',
   );
   const [stripTracking, setStripTracking] = useSetting(settingsAtom, 'stripTrackingParams');
+  const [stripImageMeta, setStripImageMeta] = useSetting(settingsAtom, 'stripImageMetadata');
 
   return (
     <Box direction="Column" gap="100">
@@ -1453,6 +1454,13 @@ function Privacy() {
           after={<Switch variant="Primary" value={stripTracking} onChange={setStripTracking} />}
         />
       </SequenceCard>
+      <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
+        <SettingTile
+          title="Remove Photo Metadata Before Sending"
+          description="Strip location, camera model and timestamp (EXIF/XMP) from JPEG, PNG and WebP images you send or set as an avatar. Pixels are untouched; the rotation is kept. Videos and GIFs are not covered."
+          after={<Switch variant="Primary" value={stripImageMeta} onChange={setStripImageMeta} />}
+        />
+      </SequenceCard>
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
         <SettingTile
           title="Hide Typing & Read Receipts"

src/app/pages/client/share/Share.tsx

@@ -15,6 +15,8 @@ import {
 } from 'folds';
 import { Room } from 'matrix-js-sdk';
 import { useAtomValue, useStore } from 'jotai';
+import { useSetting } from '../../../state/hooks/settings';
+import { settingsAtom } from '../../../state/settings';
 import { Page, PageContent, PageHeader } from '../../../components/page';
 import { useMatrixClient } from '../../../hooks/useMatrixClient';
 import { useMediaAuthentication } from '../../../hooks/useMediaAuthentication';
@@ -53,6 +55,7 @@ export function Share() {
   const [shared, setShared] = useState<Shared | null | undefined>(undefined);
   const [query, setQuery] = useState('');
   const [busy, setBusy] = useState(false);
+  const [stripImageMetadata] = useSetting(settingsAtom, 'stripImageMetadata');
 
   useEffect(() => {
     readSharedPayload()
@@ -80,7 +83,7 @@ export function Share() {
         if (shared.files.length) {
           store.set(roomIdToUploadItemsAtomFamily(room.roomId), {
             type: 'PUT',
-            item: await filesToUploadItems(room, shared.files),
+            item: await filesToUploadItems(room, shared.files, stripImageMetadata),
           });
         }
         const text = shareDraftText(shared.payload);
@@ -95,7 +98,7 @@ export function Share() {
         setBusy(false);
       }
     },
-    [shared, busy, navigateRoom, store],
+    [shared, busy, navigateRoom, store, stripImageMetadata],
   );
 
   return (

src/app/state/room/roomInputDrafts.ts

@@ -15,6 +15,8 @@ export type TUploadMetadata = {
   compressImage?: boolean;
   /** Cached compression result (populated in the background when compressImage is set to true) */
   compressionResult?: CompressionResult | null;
+  /** [Gitea #109] EXIF/XMP/IPTC was removed from this image before upload. */
+  metadataStripped?: boolean;
 };
 
 export type TUploadItem = {

src/app/state/settings.ts

@@ -268,6 +268,9 @@ export interface Settings {
   // [Gitea #103] Remove utm_/fbclid/… tracking params from links you paste or
   // send, and from links rendered in the timeline. Local only.
   stripTrackingParams: boolean;
+  // [Gitea #109] Drop EXIF/XMP/IPTC (GPS, camera, timestamp) from JPEG/PNG/WebP
+  // uploads without re-encoding. Default on.
+  stripImageMetadata: boolean;
 
   // [Gitea #104] Mirror user preferences to `io.lotus.settings` account data
   // so other devices pick them up. Device-local itself (utils/settingsSync).
@@ -390,6 +393,7 @@ const defaultSettings: Settings = {
   warnOnUnverifiedDevices: false,
 
   stripTrackingParams: true,
+  stripImageMetadata: true,
 
   settingsSync: true,
 

src/app/utils/stripImageMetadata.test.ts

@@ -0,0 +1,125 @@
+/* eslint-disable no-bitwise -- byte-level container parsing */
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import {
+  buildOrientationApp1,
+  readJpegOrientation,
+  stripJpeg,
+  stripPng,
+  stripWebp,
+  stripImageMetadataBytes,
+} from './stripImageMetadata';
+
+const here = path.dirname(fileURLToPath(import.meta.url));
+const fixture = (name: string) =>
+  new Uint8Array(fs.readFileSync(path.join(here, '__fixtures__', name)));
+const has = (bytes: Uint8Array, text: string) =>
+  Buffer.from(bytes).includes(Buffer.from(text, 'latin1'));
+
+/** Walk JPEG segments up to SOS; returns marker list (sanity: structure intact). */
+const jpegMarkers = (b: Uint8Array): string[] => {
+  const out: string[] = [];
+  let pos = 2;
+  while (pos + 4 <= b.length && b[pos] === 0xff) {
+    const m = b[pos + 1];
+    out.push(m.toString(16));
+    if (m === 0xda) break;
+    pos += 2 + ((b[pos + 2] << 8) | b[pos + 3]);
+  }
+  return out;
+};
+
+describe('stripJpeg', () => {
+  it('removes GPS, model and timestamp, keeps a valid JPEG', () => {
+    const src = fixture('gps.jpg');
+    assert.ok(has(src, 'LotusPhone 9'));
+    const { out, stripped } = stripJpeg(src);
+    assert.equal(stripped, true);
+    assert.ok(!has(out, 'LotusPhone 9'));
+    assert.ok(!has(out, '2026:09:20'));
+    assert.ok(out.length < src.length);
+    assert.deepEqual([out[0], out[1]], [0xff, 0xd8]);
+    assert.deepEqual([out[out.length - 2], out[out.length - 1]], [0xff, 0xd9]);
+    assert.ok(jpegMarkers(out).includes('da'));
+    // Pixel data untouched: everything from SOS on is byte-identical.
+    const sos = (b: Uint8Array) => Buffer.from(b).indexOf(Buffer.from([0xff, 0xda]));
+    assert.deepEqual(Buffer.from(out.subarray(sos(out))), Buffer.from(src.subarray(sos(src))));
+  });
+
+  it('keeps a non-default orientation in a minimal EXIF block', () => {
+    const { out, orientation } = stripJpeg(fixture('gps.jpg'));
+    assert.equal(orientation, 6);
+    const markers = jpegMarkers(out);
+    assert.ok(markers.includes('e1'));
+    // Find the APP1 we wrote and read the orientation back.
+    let pos = 2;
+    let found: number | undefined;
+    while (pos + 4 <= out.length && out[pos] === 0xff) {
+      const len = (out[pos + 2] << 8) | out[pos + 3];
+      if (out[pos + 1] === 0xe1) {
+        found = readJpegOrientation(out.subarray(pos + 4, pos + 2 + len));
+        assert.equal(len, buildOrientationApp1(6).length - 2);
+      }
+      if (out[pos + 1] === 0xda) break;
+      pos += 2 + len;
+    }
+    assert.equal(found, 6);
+    assert.ok(!has(out, 'LotusPhone 9'));
+  });
+
+  it('drops EXIF and the comment segment when orientation is 1 (no EXIF written back)', () => {
+    const src = fixture('plain.jpg');
+    assert.ok(has(src, 'made with love'));
+    const { out, stripped, orientation } = stripJpeg(src);
+    assert.equal(stripped, true);
+    assert.equal(orientation, undefined);
+    assert.ok(!has(out, 'made with love'));
+    assert.ok(!has(out, 'Cam'));
+    assert.ok(!jpegMarkers(out).includes('e1'));
+  });
+
+  it('returns the input untouched when there is nothing to strip', () => {
+    const src = fixture('clean.jpg');
+    const { out, stripped } = stripJpeg(src);
+    assert.equal(stripped, false);
+    assert.equal(out, src);
+  });
+});
+
+describe('stripPng', () => {
+  it('drops eXIf and text chunks, keeps IHDR/IDAT/IEND', () => {
+    const src = fixture('meta.png');
+    assert.ok(has(src, 'xmpmeta'));
+    const { out, stripped } = stripPng(src);
+    assert.equal(stripped, true);
+    assert.ok(!has(out, 'xmpmeta'));
+    assert.ok(!has(out, 'LotusPhone'));
+    assert.ok(!has(out, 'eXIf'));
+    assert.ok(has(out, 'IHDR') && has(out, 'IDAT') && has(out, 'IEND'));
+  });
+});
+
+describe('stripWebp', () => {
+  it('drops the EXIF chunk, clears the VP8X flag and fixes the RIFF size', () => {
+    const src = fixture('meta.webp');
+    assert.ok(has(src, 'LotusPhone'));
+    const { out, stripped } = stripWebp(src);
+    assert.equal(stripped, true);
+    assert.ok(!has(out, 'LotusPhone'));
+    assert.ok(!has(out, 'EXIF'));
+    const riff = out[4] | (out[5] << 8) | (out[6] << 16) | (out[7] << 24);
+    assert.equal(riff, out.length - 8);
+    const vp8x = Buffer.from(out).indexOf(Buffer.from('VP8X'));
+    if (vp8x !== -1) assert.equal(out[vp8x + 8] & 0x0c, 0);
+  });
+});
+
+describe('stripImageMetadataBytes', () => {
+  it('passes unknown types through', () => {
+    const b = new Uint8Array([1, 2, 3]);
+    assert.deepEqual(stripImageMetadataBytes(b, 'image/gif'), { out: b, stripped: false });
+  });
+});

src/app/utils/stripImageMetadata.ts

@@ -0,0 +1,250 @@
+/* eslint-disable no-bitwise -- byte-level container parsing */
+/**
+ * [Gitea #109] Remove EXIF / XMP / IPTC metadata from an image WITHOUT
+ * re-encoding its pixels, so phone photos stop carrying GPS coordinates,
+ * device model and timestamps into the room. JPEG, PNG and WebP are handled
+ * at the container level; anything else is returned untouched.
+ *
+ * JPEG orientation: a bare strip would un-rotate photos whose pixels are
+ * stored sideways, so when the EXIF Orientation tag is not 1 a minimal EXIF
+ * block carrying only that tag is written back.
+ */
+
+export type StripResult = {
+  blob: Blob;
+  /** Whether any metadata segment was actually removed. */
+  stripped: boolean;
+  /** EXIF orientation that was preserved (JPEG only), if any. */
+  orientation?: number;
+};
+
+const EXIF_HEADER = [0x45, 0x78, 0x69, 0x66, 0x00, 0x00]; // "Exif\0\0"
+
+/** Read the EXIF Orientation tag (1–8) from an APP1 payload, or undefined. */
+export function readJpegOrientation(app1: Uint8Array): number | undefined {
+  if (app1.length < 14) return undefined;
+  for (let i = 0; i < 6; i += 1) if (app1[i] !== EXIF_HEADER[i]) return undefined;
+  const tiff = 6;
+  const le = app1[tiff] === 0x49 && app1[tiff + 1] === 0x49;
+  const view = new DataView(app1.buffer, app1.byteOffset, app1.byteLength);
+  const u16 = (o: number) => view.getUint16(o, le);
+  const u32 = (o: number) => view.getUint32(o, le);
+  if (u16(tiff + 2) !== 0x2a) return undefined;
+  const ifd0 = tiff + u32(tiff + 4);
+  if (ifd0 + 2 > app1.length) return undefined;
+  const count = u16(ifd0);
+  for (let i = 0; i < count; i += 1) {
+    const entry = ifd0 + 2 + i * 12;
+    if (entry + 12 > app1.length) return undefined;
+    if (u16(entry) === 0x0112) {
+      const value = u16(entry + 8);
+      return value >= 1 && value <= 8 ? value : undefined;
+    }
+  }
+  return undefined;
+}
+
+/** A minimal APP1 segment: EXIF header + TIFF + one IFD0 entry (Orientation). */
+export function buildOrientationApp1(orientation: number): Uint8Array {
+  // TIFF (big-endian): "MM", 0x002A, IFD offset 8; IFD0: count 1, entry, next 0.
+  const tiff = new Uint8Array([
+    0x4d,
+    0x4d,
+    0x00,
+    0x2a,
+    0x00,
+    0x00,
+    0x00,
+    0x08,
+    0x00,
+    0x01,
+    0x01,
+    0x12,
+    0x00,
+    0x03,
+    0x00,
+    0x00,
+    0x00,
+    0x01,
+    0x00,
+    orientation & 0xff,
+    0x00,
+    0x00,
+    0x00,
+    0x00,
+    0x00,
+    0x00,
+  ]);
+  const payload = new Uint8Array(EXIF_HEADER.length + tiff.length);
+  payload.set(EXIF_HEADER, 0);
+  payload.set(tiff, EXIF_HEADER.length);
+  const seg = new Uint8Array(4 + payload.length);
+  seg[0] = 0xff;
+  seg[1] = 0xe1;
+  const len = payload.length + 2;
+  seg[2] = (len >> 8) & 0xff;
+  seg[3] = len & 0xff;
+  seg.set(payload, 4);
+  return seg;
+}
+
+/** JPEG: drop APP1 (EXIF/XMP), APP13 (IPTC), COM; keep JFIF/ICC and the image. */
+export function stripJpeg(bytes: Uint8Array): {
+  out: Uint8Array;
+  stripped: boolean;
+  orientation?: number;
+} {
+  if (bytes.length < 4 || bytes[0] !== 0xff || bytes[1] !== 0xd8)
+    return { out: bytes, stripped: false };
+  const parts: Uint8Array[] = [bytes.subarray(0, 2)];
+  let pos = 2;
+  let stripped = false;
+  let orientation: number | undefined;
+  let insertedOrientation = false;
+  while (pos + 4 <= bytes.length) {
+    if (bytes[pos] !== 0xff) break;
+    const marker = bytes[pos + 1];
+    // Start of scan: everything from here to the end is entropy-coded data.
+    if (marker === 0xda) break;
+    const len = (bytes[pos + 2] << 8) | bytes[pos + 3];
+    const segEnd = pos + 2 + len;
+    if (len < 2 || segEnd > bytes.length) break;
+    const drop = marker === 0xe1 || marker === 0xed || marker === 0xfe;
+    if (drop) {
+      stripped = true;
+      if (marker === 0xe1 && orientation === undefined) {
+        orientation = readJpegOrientation(bytes.subarray(pos + 4, segEnd));
+      }
+    } else {
+      parts.push(bytes.subarray(pos, segEnd));
+    }
+    pos = segEnd;
+    // Put the orientation-only EXIF right after SOI/JFIF, before anything else.
+    if (!insertedOrientation && orientation !== undefined && orientation !== 1 && marker !== 0xe0) {
+      insertedOrientation = true;
+      parts.push(buildOrientationApp1(orientation));
+    }
+  }
+  if (!stripped) return { out: bytes, stripped: false };
+  if (orientation !== undefined && orientation !== 1 && !insertedOrientation) {
+    parts.push(buildOrientationApp1(orientation));
+  }
+  parts.push(bytes.subarray(pos));
+  const total = parts.reduce((n, p) => n + p.length, 0);
+  const out = new Uint8Array(total);
+  let o = 0;
+  parts.forEach((p) => {
+    out.set(p, o);
+    o += p.length;
+  });
+  return { out, stripped, orientation: orientation !== 1 ? orientation : undefined };
+}
+
+const PNG_SIG = [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a];
+const PNG_DROP = new Set(['eXIf', 'tEXt', 'iTXt', 'zTXt', 'tIME']);
+
+/** PNG: drop eXIf and text chunks (XMP lives in iTXt); keep colour chunks. */
+export function stripPng(bytes: Uint8Array): { out: Uint8Array; stripped: boolean } {
+  if (bytes.length < 8) return { out: bytes, stripped: false };
+  for (let i = 0; i < 8; i += 1)
+    if (bytes[i] !== PNG_SIG[i]) return { out: bytes, stripped: false };
+  const parts: Uint8Array[] = [bytes.subarray(0, 8)];
+  let pos = 8;
+  let stripped = false;
+  while (pos + 8 <= bytes.length) {
+    const len =
+      ((bytes[pos] << 24) | (bytes[pos + 1] << 16) | (bytes[pos + 2] << 8) | bytes[pos + 3]) >>> 0;
+    const type = String.fromCharCode(
+      bytes[pos + 4],
+      bytes[pos + 5],
+      bytes[pos + 6],
+      bytes[pos + 7],
+    );
+    const end = pos + 12 + len;
+    if (end > bytes.length) break;
+    if (PNG_DROP.has(type)) stripped = true;
+    else parts.push(bytes.subarray(pos, end));
+    pos = end;
+  }
+  if (!stripped) return { out: bytes, stripped: false };
+  parts.push(bytes.subarray(pos));
+  const total = parts.reduce((n, p) => n + p.length, 0);
+  const out = new Uint8Array(total);
+  let o = 0;
+  parts.forEach((p) => {
+    out.set(p, o);
+    o += p.length;
+  });
+  return { out, stripped };
+}
+
+const fourcc = (b: Uint8Array, o: number) =>
+  String.fromCharCode(b[o], b[o + 1], b[o + 2], b[o + 3]);
+
+/** WebP: drop EXIF/XMP chunks and clear their VP8X flags; fix the RIFF size. */
+export function stripWebp(bytes: Uint8Array): { out: Uint8Array; stripped: boolean } {
+  if (bytes.length < 12 || fourcc(bytes, 0) !== 'RIFF' || fourcc(bytes, 8) !== 'WEBP') {
+    return { out: bytes, stripped: false };
+  }
+  const chunks: Uint8Array[] = [];
+  let pos = 12;
+  let stripped = false;
+  let vp8x: Uint8Array | undefined;
+  while (pos + 8 <= bytes.length) {
+    const id = fourcc(bytes, pos);
+    const len =
+      (bytes[pos + 4] | (bytes[pos + 5] << 8) | (bytes[pos + 6] << 16) | (bytes[pos + 7] << 24)) >>>
+      0;
+    const end = pos + 8 + len + (len % 2);
+    if (pos + 8 + len > bytes.length) break;
+    if (id === 'EXIF' || id === 'XMP ') stripped = true;
+    else {
+      const chunk = bytes.slice(pos, Math.min(end, bytes.length));
+      if (id === 'VP8X') vp8x = chunk;
+      chunks.push(chunk);
+    }
+    pos = end;
+  }
+  if (!stripped) return { out: bytes, stripped: false };
+  // VP8X flags byte: bit 3 = EXIF, bit 2 = XMP (0x08 / 0x04).
+  if (vp8x && vp8x.length >= 9) vp8x[8] &= ~0x0c;
+  const body = chunks.reduce((n, c) => n + c.length, 0);
+  const out = new Uint8Array(12 + body);
+  out.set(bytes.subarray(0, 12), 0);
+  const riffSize = 4 + body;
+  out[4] = riffSize & 0xff;
+  out[5] = (riffSize >> 8) & 0xff;
+  out[6] = (riffSize >> 16) & 0xff;
+  out[7] = (riffSize >> 24) & 0xff;
+  let o = 12;
+  chunks.forEach((c) => {
+    out.set(c, o);
+    o += c.length;
+  });
+  return { out, stripped };
+}
+
+export const STRIPPABLE_TYPES = ['image/jpeg', 'image/png', 'image/webp'];
+
+export function stripImageMetadataBytes(
+  bytes: Uint8Array,
+  mimeType: string,
+): { out: Uint8Array; stripped: boolean; orientation?: number } {
+  if (mimeType === 'image/jpeg') return stripJpeg(bytes);
+  if (mimeType === 'image/png') return stripPng(bytes);
+  if (mimeType === 'image/webp') return stripWebp(bytes);
+  return { out: bytes, stripped: false };
+}
+
+/** Strip a File/Blob; returns the same object when nothing changed or the type is unsupported. */
+export async function stripImageMetadata(file: File): Promise<StripResult & { file: File }> {
+  if (!STRIPPABLE_TYPES.includes(file.type)) return { blob: file, file, stripped: false };
+  const bytes = new Uint8Array(await file.arrayBuffer());
+  const { out, stripped, orientation } = stripImageMetadataBytes(bytes, file.type);
+  if (!stripped) return { blob: file, file, stripped: false };
+  const next = new File([out as BlobPart], file.name, {
+    type: file.type,
+    lastModified: file.lastModified,
+  });
+  return { blob: next, file: next, stripped: true, orientation };
+}

src/app/utils/uploadItems.ts

@@ -3,20 +3,44 @@ import { TUploadItem } from '../state/room/roomInputDrafts';
 import { encryptFile } from './matrix';
 import { safeFile } from './mimeTypes';
 import { fulfilledPromiseSettledResult } from './common';
+import { stripImageMetadata } from './stripImageMetadata';
 
 /**
  * Files → composer upload items for `room`, encrypting first when the room
  * is E2EE. Shared by the composer's pick/drop/paste paths and the PWA share
  * target (#155).
  */
-export async function filesToUploadItems(room: Room, files: File[]): Promise<TUploadItem[]> {
-  const safeFiles = files.map(safeFile);
-  const metadata = { markedAsSpoiler: false };
+export async function filesToUploadItems(
+  room: Room,
+  files: File[],
+  stripMetadata = true,
+): Promise<TUploadItem[]> {
+  const prepared = await Promise.all(
+    files.map(async (raw) => {
+      const f = safeFile(raw);
+      // [Gitea #109] Drop EXIF/XMP/IPTC before anything else sees the bytes
+      // (including encryption), so what's uploaded never carried them.
+      const { file, stripped } = stripMetadata
+        ? await stripImageMetadata(f)
+        : { file: f, stripped: false };
+      return {
+        file,
+        metadata: { markedAsSpoiler: false, metadataStripped: stripped || undefined },
+      };
+    }),
+  );
   if (room.hasEncryptionStateEvent()) {
     const encrypted = fulfilledPromiseSettledResult(
-      await Promise.allSettled(safeFiles.map((f) => encryptFile(f))),
+      await Promise.allSettled(
+        prepared.map(async ({ file, metadata }) => ({ ...(await encryptFile(file)), metadata })),
+      ),
     );
-    return encrypted.map((ef) => ({ ...ef, metadata }));
+    return encrypted;
   }
-  return safeFiles.map((f) => ({ file: f, originalFile: f, encInfo: undefined, metadata }));
+  return prepared.map(({ file, metadata }) => ({
+    file,
+    originalFile: file,
+    encInfo: undefined,
+    metadata,
+  }));
 }