Biblio

In recent years, many modifications have been done to combat the weaknesses of the Vigenère Cipher Algorithm. Several studies have been carried out to rectify the flaw of the algorithm’s repeating key nature by increasing the key length equal to that of the plain text. However, some characters cannot be encrypted due to the limited set of characters in the key. This paper modified the algorithm’s key generation process using a Pseudo-Random Number Generator to improve the algorithm’s security and expanded the table of characters to up to 190 characters. The results show that based on Monobit examination and frequency analysis, the repeating nature of the key is non-existent, and the generated key can be used to encrypt a larger set of characters. The ciphertext has a low IC value of 0.030, which is similar to a random string and polyalphabetic cipher with an IC value of 0.038 but not equal to a monoalphabetic cipher with an IC value of 0.065. Results show that the modified version of the algorithm performs better than some of the recent studies conducted on it

Cryptography is a method of storing and transmitting data in a particular form. Only those for whom it is intended can read, use it, and return it back to the original data by using various techniques. The International Data Encryption Algorithm "IDEA" is a block cipher that works with 64-bit plaintext block and ciphertext blocks and it has a 128-bit input key. This paper describe the designing and implementation of a modified key schedule operation of IDEA called GISKOP. It uses the same number of rounds and output transformation that operates using 128 bit user input plaintext and a modified way of key scheduling operation of 256 bit keys. The modified algorithm uses Serpent key scheduling operation to derive the different sub keys to be used in each rounds. The algorithm was implemented to provide better security on user's password within the Document Management System to protect user's data within the cloud database. It has gone through initial testing and evaluations with very encouraging results.

Random numbers are important tools for generating secret keys, encrypting messages, or masking the content of certain protocols with a random sequence that can be deterministically generated. The lack of assurance about the random numbers generated can cause serious damage to cryptographic protocols, prompting vulnerabilities to be exploited by the attackers. In this paper, a new pseudo - random number generator algorithm that uses dynamic system clock converted to Epoch Timestamp as PRNG seed was developed. The algorithm uses a Linear Congruential Generator (LCG) algorithm that produces a sequence of pseudo - randomized numbers that performs mathematical operations to transform numbers that appears to be unrelated to the Seed. Simulation result shows that the new PRNG algorithm does not generate repeated random numbers based on the frequency of iteration, a good indicator that the key for random numbers is secured. Numerical analysis using NIST Test Suite results concerning to random sequences generated random numbers has a total average of 0.342 P-value. For a p-value ≥ 0.001, a sequence would be considered to be random with a confidence of 99.9%. This shows that robustness and unpredictability were achieved. Hence, It is highly deterministic in nature and has a good quality of Pseudo-Random Numbers. It is therefore a good source of a session key generation for encryption, reciprocal in the authentication schemes and other cryptographic algorithm parameters that improve and secure data from any type of security attack.

Network steganography is a branch of steganography that hides information through packet header manipulation and uses protocols as carriers to hide secret information. Many techniques were already developed using the Transmission Control Protocol (TCP) headers. Among the schemes in hiding information in the TCP header, the Initial Sequence Number (ISN) field is the most difficult to be detected since this field can have arbitrary values within the requirements of the standard. In this paper, a more undetectable scheme is proposed by increasing the complexity of hiding data in the TCP ISN using dynamic identifiers. The experimental results have shown that using Bayes Net, the proposed scheme outperforms the existing scheme with a low detection accuracy of 0.52%.

The integration of subset sum in the verifiable secret sharing scheme provides added security measure for a multiparty computation such as immediate identification of and removal of an imposter, avoidance or discourages man-in-the-middle attack and lattice-based attack, and lessens dealer's burden on processing monitoring the integrity of shareholders. This study focuses on the security assessment of a brute-force attack on the subset sum-based verifiable secret sharing scheme. With the simulation done using a generator of all possible fixed-length partition (which is k=3 as the least possible) summing up to the sum of the original subset generated by the dealer, it shows that it will already took 11,408 years to brute-force all possible values even on a small 32-bit-length value and 3.8455 years for a 128-bit length value thus proving that the resiliency on brute attack on the subset sum based VSSS can be discounted despite simplicity of the implementation. Zero knowledge on the number of threshold will also multiply to the impossibility of the brute force attack.