# Build an APP2 marker: 0xFFE2 + length (2 bytes) + payload # Length includes the two length bytes themselves. length = len(payload_bytes) + 2 app2_marker = b'\xFF\xE2' + struct.pack('>H', length) + payload_bytes
# Usage payload = b'LovelyAlazaiPatchV1' # any bytes you want to embed add_app2('lovely_alazai.jpg', 'lovely_alazai_patched.jpg', payload) # Show all APP markers; you should see the new APP2 entry exiftool -a -G1 -s lovely_alazai_patched.jpg The output will list something like: filedot lovely alazai jpg patched
# Locate the end of the SOI marker (first two bytes) if data[:2] != b'\xFF\xD8': raise ValueError('Not a valid JPEG (missing SOI)') # Build an APP2 marker: 0xFFE2 + length
# Write the patched file with open(out_path, 'wb') as f: f.write(patched) payload) # Show all APP markers
[APP2] LovelyAlazaiPatchV1 If you suspect a JPEG contains unwanted data after the EOI marker, you can strip everything beyond 0xFFD9 :
def add_app2(jpeg_path, out_path, payload_bytes): # Read the original JPEG as raw bytes with open(jpeg_path, 'rb') as f: data = f.read()