Secure image authentication with discrete level tamper localization

A computer-readable medium comprising computer-program instructions executable by a processor for:

• evaluating multimedia to determine authenticity of the multimedia based on data block(s), the multimedia includes a digital signature, keyed hash, or MAC embedded in secretly selected pixels, and the evaluating comprises:
• extracting the digital signature, keyed hash, or MAC from the selected pixels;
• if digital signature is used, decrypting to recover a first hash value;
• if keyed hash or MAC, the keyed hash or MAC is a first hash value;
• zeroing out particular bits of a particular disjoint subspace of a plurality of disjoint subspaces determined by same operations used to authentication-sign multimedia;
• hashing bits of the disjoint subspaces to obtain a second hash value;
• comparing the first hash value with the second hash value;
• and
• responsive to the comparing, determining that the multimedia is authentic or inauthentic;
• and
• responsive to determining that the multimedia is not authentic, localizing a tampered portion of the multimedia, the localizing addressing each respective pixel or sample of the tampered portion.

A computing device comprising:

• a processor;
• and
• a memory coupled to the processor, the memory comprising computer-program instructions executable by the processor and comprising instructions for:
• evaluating multimedia to determine authenticity of the multimedia, the evaluating being based on data block(s);
• and
• responsive to determining that the multimedia is not authentic, localizing a tampered portion of the multimedia, the instruction for localizing further comprising instructions for:
• shuffling a challenged image to generate a shuffled image with randomized neighborhood data;
• converting the shuffled image and an original logo image into lower dimension vectors;
• the original logo image being a second image embedded into the multimedia to be signed in a signing procedure to detect tampered pixels or samples;
• extract the embedded logo from a lower dimension vector of the lower dimension vectors that corresponds to the challenged image comparing the extracted logo with the original logo to identify mis-matched pixel(s) or sample(s);
• scanning the lower dimension vectors to higher dimension vectors by reversing previously applied dimension reduction operations;
• reversing the shuffling operation to locate particular pixel(s) or samples of the multimedia that correspond to the mismatched pixel(s) or sample(s) in the shuffled image;
• and
• wherein the particular pixel(s) or sample(s) are tampered pixel(s) or sample(s).

A computing device comprising:

• evaluating means to determine authenticity of multimedia as a function of data block(s), the evaluating means further comprises:
• extracting means to extract data from the multimedia, the data comprising a digital signature, keyed hash, or MAC, from a set of pixels or samples selected for embedding;
• if digital signature is used, decrypting means to recover a first hash value;
• if keyed hash or MAC, the keyed hash or MAC is a first hash value;
• zeroing means to enforce a relationship with respect to particular bits of a particular disjoint subspace of a plurality of disjoint subspaces determined by the same operations used to sign the multimedia;
• hashing means to hash bits of the disjoint subspaces to obtain a second hash value;
• comparing means to compare the first hash value with the second hash value;
• and
• responsive to the comparing, determining means to determine that the multimedia is authentic or inauthentic;
• and
• responsive to determining that the multimedia is not authentic, localizing means to identify a tampered portion of the multimedia, the localizing addressing each respective pixel or sample of the tampered portion.