Digital Signature Protocol for Visual Authentication

Information security in digital domain is all about assurance of Confidentiality, Integrity, Availability (CIA) extending authenticity and non-repudiation issues. Major concerns towards implementation of information security are computational overhead, implementation complexity and robustness of the protocol. In this paper, we proposed a solution to achieve the target in line with state of the art information security protocol. The computational overhead is significantly reduced without compromising the uncertainty in key pair generation like existing digital signature schemes. The first section deals with collection of digitized signature from an authentic user, generation of shares from the signature, conversion of a cover image to quantized frequency form and casting of a share in appropriate coefficients. In the second section, share detection is done effectively and the data security is confirmed by overlapping the detected share with the other share. Specific constraints are fitted appropriately to recreate a clean digitized signature, reform the cover image using Discrete Cosine Transform (DCT) and quantization method, select frequency coefficients for share casting and manipulate the casting intensity. Impressive effort is made to ensure resistance to some of the common image processing attacks. The undesired white noise is reduced considerably by choosing a suitable threshold value. The selection of pseudorandom hiding position also helps to increase the robustness and the experimental results supports the efficacy of the algorithm.