The development history of Umkehrwalze Dora (UKWD), Enigma's pluggable reflector, is presented from the first ideas in the mid-1920s to the last development plans and its actual usage in 1945. An Enigma message in three parts, enciphered with UKWD and intercepted by the British on 11 March 1945, is shown. The successful recovery of the key of this message is described. Modern computer-based cry...

A5/1 is a shift register based stream cipher which uses a majority clocking rule to update its registers. It is designed to provide privacy for the GSM system. In this paper, we analyse the initialisation process of A5/1. We demonstrate a sliding property of the A5/1 cipher, where every valid internal state is also a legitimate loaded state and multiple key-IV pairs produce phase shifted keystr...

The PCBC block cipher mode of operation has many variants, of which one, due to Meyer and Matyas, dates back over 20 years. Whilst a particularly simple variant of PCBC has long been known to be very weak when used for data integrity protection, the Meyer-Matyas variant has not previously been attacked. In this paper we cryptanalyse this mode, and show that it possesses a serious weakness when ...

Irregularly-clocked linear feedback shift registers (LFSRs) are commonly used in stream ciphers. We propose to harness the power of conditional estimators for correlation attacks on these ciphers. Conditional estimators compensate for some of the obfuscating effects of the irregular clocking, resulting in a correlation with a considerably higher bias. On GSM’s cipher A5/1, a factor two is gaine...

In this paper we study a 128-bit-key cipher called PC1 which is used as part of the DRM system of the Amazon Kindle e-book reader. This is the first academic cryptanalysis of this cipher and it shows that PC1 is a very weak stream cipher, and can be practically broken in a known-plaintext and even in a ciphertext-only scenario. A hash function based on this cipher has also been proposed and is ...

Abstract— Multi-secret sharing scheme based on cellular automata have proven to be a secure encrypting algorithm, although it cannot guarantee data integrity and authenticity of shares of the participants, allowing a chosen cipher text attack. In this work, to improve the security of multiple secret sharing scheme (SSS) against adaptive chosen cipher text attack, we introduce an authenticated e...

In this article, we provide the first third-party security analysis of the PRINCE lightweight block cipher, and the underlying PRINCEcore. First, while no claim was made by the authors regarding related-key attacks, we show that one can attack the full cipher with only a single pair of related keys, and then reuse the same idea to derive an attack in the single-key model for the full PRINCEcore...

A novel bit level block cipher based symmetric key cryptographic technique using G.C.D is proposed in this research paper. Entire plain text file is read one character at a time and according to the binary representation of ASCII value of the characters, entire plain text file is divided into n number of 16 bit blocks. Then an agreed-upon symmetric key file is formed by dividing each 16 bit blo...

We present a method for eecient conversion of diierential (chosen-plaintext) attacks into the more practical known-plaintext and ciphertext-only attacks. Our observation may save up to a factor of 2 20 in data over the known methods, assuming that plaintext is ASCII encoded English (or some other types of highly redundant data). We demonstrate the eeectiveness of our method by practical attacks...