Digital Signatures Chain and El Gamal Scheme Integration for Data Transmission Integrity in Digital Transaction

Digital signatures have been widely used by both private and government agencies. However, the use of chain digital signatures is still not widely used, especially in the military world. This results in a lack of ability to ensure data integrity, where it will be difficult to find out who has made changes to the document and to find out the original source of the document. This paper proposes a digital signature chain as a solution to guarantee data authenticity and prevent tampering during transmission. This technique involves creating a chain of digital signatures that are attached to data before it is sent over the network. The proposed method is expected to provide a more secure and efficient way to ensure data integrity, compared to traditional methods such as encryption and checksums. This paper evaluates the effectiveness of the proposed method through a series of experiments and shows that digital signature chains are an effective and reliable way to secure and maintain data transmission over networks. The proposed research aims to evaluate the effectiveness of digital signature chain technology in ensuring data security and integrity and to provide recommendations for its implementation

The zheng-seberry public key cryptosystem and signcryption

In 1993 Zheng-Seberry presented a public key cryptosystem that was considered efficient and secure in the sense of indistinguishability of encryptions (IND) against an adaptively chosen ciphertext adversary (CCA2). This thesis shows the Zheng-Seberry scheme is not secure as a CCA2 adversary can break the scheme in the sense of IND. In 1998 Cramer-Shoup presented a scheme that was secure against an IND-CCA2 adversary and whose proof relied only on standard assumptions. This thesis modifies this proof and applies it to a modified version of the El-Gamal scheme. This resulted in a provably secure scheme relying on the Random Oracle (RO) model, which is more efficient than the original Cramer-Shoup scheme. Although the RO model assumption is needed for security of this new El-Gamal variant, it only relies on it in a minimal way

Agri-Food Traceability Management using a RFID System with Privacy Protection

In this paper an agri-food traceability system based on public key cryptography and Radio Frequency Identification (RFID) technology is proposed. In order to guarantee safety in food, an efficient tracking and tracing system is required. RFID devices allow recording all useful information for traceability directly on the commodity. The security issues are discussed and two different methods based on public cryptography are proposed and evaluated. The first algorithm uses a nested RSA based structure to improve security, while the second also provides authenticity of data. An experimental analysis demonstrated that the proposed system is well suitable on PDAs to

Distributed Provers and Verifiable Secret Sharing Based on the Discrete Logarithm Problem

Secret sharing allows a secret key to be distributed among n persons, such that k(1 <= k <= n) of these must be present in order to recover it at a later time. This report first shows how this can be done such that every person can verify (by himself) that his part of the secret is correct even though fewer than k persons get no Shannon information about the secret. However, this high level of security is not needed in public key schemes, where the secret key is uniquely determined by a corresponding public key. It is therefore shown how such a secret key (which can be used to sign messages or decipher cipher texts) can be distributed. This scheme has the property, that even though everybody can verify his own part, sets of fewer than k persons cannot sign/decipher unless they could have done so given just the public key. This scheme has the additional property that more than k persons can use the key without compromising their parts of it. Hence, the key can be reused. This technique is further developed to be applied to undeniable signatures. These signatures differ from traditional signatures as they can only be verified with the signer's assistance. The report shows how the signer can authorize agents who can help verifying signatures, but they cannot sign (unless the signer permits it)

A public-key cryptosystem based on second order linear sequences

Based on Lucas functions, an improved version of the Diffie-Hellman distribution key scheme and to the ElGamal public key cryptosystem scheme are proposed, together with an implementation and computational cost. The security relies on the difficulty of factoring an RSA integer and on the difficulty of computing the discrete logarithm

Enhancing cloud computing security by paillier homomorphic encryption

In recent years, the trend has increased for the use of cloud computing, which provides broad capabilities with the sharing of resources, and thus it is possible to store and process data in the cloud remotely, but this (cloud) is untrusted because some parties can connect to the network such as the internet and read or change data because it is not protected, therefore, protecting data security and privacy is one of the challenges that must be addressed when using cloud computing. Encryption is interested in the field of security, confidentiality and integrity of information that sent by a secure connection between individuals or institutions regardless of the method used to prepare this connection. But using the traditional encryption methods to encrypt the data before sending it will force the data provider to send his private key to the server to decrypt the data to perform computations on it. In this paper we present a proposal to secure banking data transmission through the cloud by using partially homomorphic encryption algorithms such as (paillier, RSA algorithm) that allow performing mathematical operations on encrypted data without needing to decryption. A proxy server will also use for performing re-encryption process to enhance security

Publicness, Privacy and Confidentiality in the Single-Serving Quantum Broadcast Channel

The 2-receiver broadcast channel is studied: a network with three parties where the transmitter and one of the receivers are the primarily involved parties and the other receiver considered as third party. The messages that are determined to be communicated are classified into public, private and confidential based on the information they convey. The public message contains information intended for both parties and is required to be decoded correctly by both of them, the private message is intended for the primary party only, however, there is no secrecy requirement imposed upon it meaning that it can possibly be exposed to the third party and finally the confidential message containing information intended exclusively for the primary party such that this information must be kept completely secret from the other receiver. A trade-off arises between the rates of the three messages, when one of the rates is high, the other rates may need to be reduced to guarantee the reliable transmission of all three messages. The encoder performs the necessary equivocation by virtue of dummy random numbers whose rate is assumed to be limited and should be considered in the trade-off as well. We study this trade-off in the one-shot regime of a quantum broadcast channel by providing achievability and (weak) converse regions. In the achievability, we prove and use a conditional version of the convex-split lemma as well as position-based decoding. By studying the asymptotic behaviour of our bounds, we will recover several well-known asymptotic results in the literature.Comment: 23 pages, 1 figure, journa

An Uninstantiable Random-Oracle-Model Scheme for a Hybrid Encryption Problem

We present a simple, natural random-oracle (RO) model scheme, for a practical goal, that is uninstantiable, meaning is proven in the RO model to meet its goal yet admits NO standard-model instantiation that meets this goal. The goal in question is IND-CCA-preserving asymmetric encryption which formally captures security of the most common practical usage of asymmetric encryption, namely to transport a symmetric key in such a way that symmetric encryption under the latter remains secure. The scheme is an ElGamal variant, called Hash ElGamal, that resembles numerous existing RO-model schemes, and on the surface shows no evidence of its anomalous properties. More generally, we show that a certain goal, that we call key-verifiable, ciphertext-verifiable IND-CCA-preserving asymmetric encryption, is achievable in the RO model (by Hash ElGamal in particular) but unachievable in the standard model. This helps us better understand the source of the anomalies in Hash ElGamal and also lifts our uninstantiability result from being about a specific scheme to being about a primitive or goal. These results extend our understanding of the gap between the standard and RO models, and bring concerns raised by previous work closer to practice by indicating that the problem of RO-model schemes admitting no secure instantiation can arise in domains where RO schemes are commonly designed