Due to the availability of powerful image editing softwares, forgers can tamper the image content easily. There are various types of image forgery, such as image splicing and region duplication forgery. Region duplication is one of the most common manipulations used for tampering digital images. It is vital in image forensics to authenticate the digital image. In this paper, a novel region dupl...

A new attack called the snoop-forge-replay attack is presented on keystroke-based continuous verification systems. The snoop-forge-replay is a sample-level forgery attack and is not specific to any particular keystroke-based continuous verification method or sysem. It can be launched with easily available keyloggers and APIs for keystroke synthesis. Our results ffrom 2460 experiments show that:...

In this article we describe new generic distinguishing and forgery attacks in the related-key scenario (using only a single related-key) for the HMAC construction. When HMAC uses a k-bit key, outputs an n-bit MAC, and is instantiated with an l-bit inner iterative hash function processing m-bit message blocks where m = k, our distinguishing-R attack requires about 2 queries which improves over t...

At Crypto’99, Dr Coron, Naccache, and Stern presented a signature forgery strategy of the RSA digital signature scheme. The attack is valid on Chaum’s blind signature scheme, which has been applied to many practical applications such as electronic cash and voting. In this paper we propose a method to inject a randomizing factor into a message when it is signed by the signer in Chaum’s blind sig...

Many of the signature schemes are proposed in which the t out of n threshold schemes are deployed; but they still lack the property of security. In this paper, we have discussed implementation of improved CCH1 and improved CCH2 proxy multi-signature scheme based on elliptic curve cryptosystem. We have represented time complexity, space complexity and computational overhead of improved CCH1 and ...

In 2014, a patient self-controllable multi-level privacypreserving cooperative authentication scheme (PSMPA) was proposed for attempting to address the issue of data confidentiality and patients’ identity privacy simultaneously when the personal healthcare record (PHR) is shared in the distributed m-healthcare cloud computing system. In this paper, we show the PSMPA scheme fails to achieve the ...

To enhance the efficiency of threshold group signature schemes, Yu and Chen, recently, proposed an efficient threshold group signature scheme. By using elliptic curves, the proposed scheme can use short secret key and reduces the load of signature verification. However, in this paper we find that there are many ambiguities in the proposed scheme. The verifiers cannot verify valid signatures, wh...

Recently, Yoon et al. and Wu proposed two improved remote mutual authentication and key agreement scheme for mobile devices on elliptic curve cryptosystem. In this paper, we show that Yoon et al.’s protocol fails to provide explicit key perfect forward secrecy and fails to achieve explicit key confirmation. We also point out Wu’s scheme decreases efficiency by using the double secret keys and i...

In 2012, Singh and Verma proposed an ID-based proxy signature scheme with message recovery. In this paper, we show that their scheme is vulnerable to the forgery attack, and an adversary can forge a valid proxy signature for any message with knowing a previous valid proxy signature. In addition, there is a security flaw in their proof. Furthermore, we propose an improved scheme that remedies th...

A three-factor authentication combines biometrics information with user password and smart card to provide security-enhanced user authentication. An proposed user authentication scheme improved Das’s scheme. But An’s scheme is not secure against denial of service attack in login phase, forgery attack. Li et al. pointed out them and proposed three-factor remote user authentication scheme with ke...