We describe a practical attack on the High Bandwidth Digital Content Protection (HDCP) scheme. HDCP is a proposed identity-based cryptosystem for use over the Digital Visual Interface bus, a consumer video bus used in digital VCRs, camcorders, and personal computers. Public/private key pairs are assigned to devices by a trusted authority, which possesses a master secret. If an attacker can reco...

Cloud storage could be a storage of information on-line in cloud that is accessible from multiple and connected resources. Cloud storage will offer smart accessibility and reliability, sturdy protection, disaster recovery, and lowest price. Cloud storage having vital practicality i.e. securely, with efficiency, flexibly sharing information with others. New public–key cryptography that is named ...

Several public key cryptosystems with additional homomor phic properties have been proposed so far They allow to perform com putation with encrypted data without the knowledge of any secret in formation In many applications the ability to perform decryption i e the knowledge of the secret key gives a huge power A classical way to reduce the trust in such a secret owner and consequently to incre...

This paper presents two modifications for Loidreau’s cryptosystem, a rank metric-based cryptosystem constructed by using Gabidulin codes in the McEliece setting. Recently polynomial-time key recovery attack was proposed to break this some cases. To prevent attack, we propose use of subcodes disguise secret Modification I. In II, choose random matrix low column mix with matrix. Our analysis show...

At the last Eurocrypt meeting, a cryptosystem based on modular knapsacks was proposed (see [11]). We show that this system is not secure, and we describe two different ways of breaking it using the LLL algorithm. This is one more example of a cryptosystem that can be broken using this powerful algorithm (see [1, 13, 14]). For more details, the reader should refer to [4]. 1 The proposed cryptosy...

Recently, Yoon et al. and Wu proposed two improved remote mutual authentication and key agreement schemes 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 ...

Yamamota's notion of partial secrecy is extended to Public Key Cryptosystems: the security of a cryptosystem depends on keeping some function of the original record secret, while sending the relevant message (also a function of the original record). Notions of security and semantic security are introduced and compared for such cryptosystems, and securitypreserving reductions between such system...

In this paper we present a new algorithm to attack lattice based cryptosystems by solving a problem over real numbers. In the case of the NTRU cryptosystem, if we assume the additional information on the modular operations, we can break the NTRU cryptosystems completely by getting the secret key. We believe that this fact was not known before.

In this paper, we address the following problem: \ Is it possible to weaken/attack a scheme when a (provably) secure cryptosystem is used? ". The answer is yes. We exploit weak error-handling methods. Our attack relies on the cryptana-lyst being able to modify some ciphertext and then getting access to the decryption of this modiied ciphertext. and Re-iter 4] presented a serious weakness in the...

A leakage-resilient cryptosystem remains secure even if arbitrary, but bounded, information about the secret key (and possibly other internal state information) is leaked to an adversary. Denote the length of the secret key by n. We show: – A full-fledged signature scheme tolerating leakage of ( 1− n− ) · n bits of information about the secret key (for any constant < 1), based on general assump...