<FONT face=Verdana>It is significantly meaningful to exactly locating the tampered areas in digital images. This paper proposes a novel fragile watermarking scheme for JPEG covers

in which the hash bits of all blocks with a size of 8×8 are pseudo-randomly reorganized as a series of subsets

and their sums with modulus 2 are regarded as watermark bits. This way

each block maps a number of watermark bits

and each watermark bit corresponds to a number of blocks. Then

a selected non-zero DCT coefficient in each block is used to accommodate one watermark bit. At authentication side

after estimating the tampering rate

the inconsistency between the calculated and extracted watermark bits of each block is used to judge it as “tampered” or “reserved”. Theoretical analysis and experimental result show that the proposed method is capable of locating all tampered blocks when the tampering rate is less than 1%.