In an intrusion-resilient cryptosystem [10], two entities (a user and a base) jointly evolve a secret decryption key; this provides very strong protection against an active attacker who can break into the user and base repeatedly and even simultaneously. Recently, a construction of an intrusion-resilient public-key encryption scheme based on specific algebraic assumptions has been shown [6]. We...

Running the key-management service of cryptographic systems in the cloud is an attractive cost saving proposition. Supporting key-recovery is an essential component of every key-management service. We observe that to verifiably support key-recovery in a public cloud, it is essential to use publicly verifiable secret-sharing (PVSS) schemes. In addition, a holistic approach to security must be ta...

In this paper we propose a novel cryptanalytic method against multivariate schemes, which adapts differential cryptanalysis to this setting. In multivariate quadratic systems, the differential of the public key is a linear map and has invariants such as the dimension of the kernel. Using linear algebra, the study of this invariant can be used to gain information on the secret key. We successful...

In this paper we propose a new approach to investigate the security of the McEliece cryptosystem. We recall that this cryptosystem relies on the use of error-correcting codes. Since its invention thirty years ago, no efficient attack had been devised that managed to recover the private key. We prove that the private key of the cryptosystem satisfies a system of bi-homogeneous polynomial equatio...

We report a break for a recently proposed class of cryptosystems. The cryptosystem uses constant points of a periodic secret orbit to encrypt the plaintext. In order to break the system, it suffices to sort the constant points and find the initial fixed point. We also report breaks for the modified versions of the cryptosystem. Besides, we discuss some efficiency issues of the the cryptosystem.

In this paper we extend the ideas for differential fault attacks on the RSA cryptosystem (see [4]) to schemes using elliptic curves. We present three different types of attacks that can be used to derive information about the secret key if bit errors can be inserted into the elliptic curve computations in a tamper-proof device. The effectiveness of the attacks was proven in a software simulatio...

In recent years, a variety of image encryption scheme has been proposed. A new color image encryption method based on dynamic key exchange is proposed in this paper. For real time image encryption and lesser amount of time. The algorithm lacks of the characteristic of diffusion because each pixel is operated individually and a chosen/known-plaintext attack can break the scheme. The 192-bit-long...

Trusted parties are fundamental for the establishment of secure communication among users. Such is the case, for example, when establishing a trusted relationship between users and certain public information in a public-key infrastructure for public-key encryption and signature schemes or when storing high-entropy secret keys in a cryptographic device. Clearly, if the trusted party misbehaves i...

In a key management scheme for hierarchy based access control, each security class having higher clearance can derive the cryptographic secret keys of its other security classes having lower clearances. In 2006 Jeng-Wang proposed an efficient scheme on access control in user hierarchy based on elliptic curve cryptosystem. Their scheme provides solution of key management efficiently for dynamic ...

This paper introduces a special type of symmetric cryptosystem called multi-encryption scheme. It allows users to encrypt multiple plaintexts into a single ciphertext. Each plaintext is protected with its own secret key, meaning that they can be decrypted individually by applying the decryption function with the corresponding key to the ciphertext. Compared to encrypting the ciphertexts one-by-...