Enhancement of Secrecy of Block Ciphered Systems by Deliberate Noise

Abstract

This paper considers the problem of end-to-end security enhancement by resorting to deliberate noise injected in ciphertexts. The main goal is to generate a degraded wiretap channel in the application layer over which Wyner-type secrecy encoding is invoked to deliver additional secure information. More specifically, we study secrecy enhancement of the Data Encryption Standard (DES) block cipher working in cipher feedback model (CFB) when adjustable noise is introduced into the encrypted data in an application layer. A verification strategy in the exhaustive search step of the linear attack is designed to allow Eve to mount a successful attack in the noisy environment. Thus, a controllable wiretap channel is created over multiple frames by taking advantage of errors in Eve's cryptanalysis, whose secrecy capacity is found for the case of known channel states at receivers. As a result, additional secure information can be delivered by performing Wyner type secrecy encoding over superframes ahead of encryption. These secrecy bits could be taken as symmetric keys for upcoming frames. Numerical results indicate that a sufficiently large secrecy rate can be achieved by selective noise addition.

An Information-Theoretic Security Evaluation of a Class of Randomized Encryption Schemes

“…This paper proposed a generic model of randomized encryption schemes, that encompasses those presented in [16], [17], [21], [22], [24], [25] and [30].…”

“…The vector x could be generated by keystream generator or by a block cipher working in the cipher feedback mode (CFB) as in [16], [17], [30] and [31].…”

“…Recently, joint employment of randomness and dedicated coding has been reported for enhancing the security of the following block-by-block encryption schemes: (i) in [21], where the basic keystream generator security is enhanced by employing a particular homophonic coding based on embedding of random bits; (ii) in [22], [24] and [25] where randomness and wire-tap channel coding have been employed for enhancing the security of the compact generators of pseudorandom vectors; (iii) in [16], [17], [30] and [31] where wire-tap channel coding is employed to increase the security of a DES block cipher operating in the ciphertext feedback (CFB) mode. Security improvements provided by (i)-(iii) include resistance against the generic time-memory trade-off [12] based attacks, and its generalizations and improvements including time-memory-data trade-off approach [3] and its variants (see [20], for example).…”

Triple Security of Data using Encryption Keys and Image Steganography

“…The system provides cryptographic security enhancement [1]- [2]. The issue of end-to-end security was upgraded by turning to consider disorder infused in ciphertext.…”

Nested and interleaved direct sequence spread spectrum to enhance CDMA security and bit error rate performance

“…The encrypted code is usually generated by applying a block cipher algorithm on an Msequence, and the resulting output can be considered confidential [14][15][16][17]. In that method, the security is applied by encrypting the spreading code employing a private key.…”