This　paper　proposes　an　authentication　scheme　for　JPEG　images　based　on　digital　signature　and　semi-fragile　watermarking.　It　can　detect　and　locate　malicious　manipulations　made　to　the　image,　and　verify　the　ownership　of　the　image　at　the　same　time.　The　algorithm　uses　the　invariance　of　the　order　relationship　between　two　DCT　coefficients　before　and　after　JPEG　compression　to　embed　image　content　dependent　watermark,　therefore　the　watermark　can　survive　the　JPEG　lossy　compression.　Since　the　scheme　is　based　on　the　security　of　the　cryptographic　hash　function　and　public　key　algorithm,　it　is　believed　to　be　secure　to　the　extent　that　cryptography　is　believed　to　be.　Theoretical　analysis　and　experimental　results　show　that　the　proposed　scheme　has　the　desired　property　and　good　performance　for　image　authentication.