An Improved Guess-and-Determine Attack on the A5/1 Stream Cipher

Mahalanobis, Ayan; Shah, Jay

doi:10.5539/cis.v7n1p115

Cited by 4 publications

(4 citation statements)

References 10 publications

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“…Some stream ciphers are susceptible to direct attacks, which exploit algebraic, key-scheduling, statistical or other structural weaknesses particular to individual crypto-algorithms [11,21,36,38,39]. If no direct attack is known, then an exhaustive key-search may be attempted.…”

Section: Stream-cipher Cryptanalysismentioning

confidence: 99%

PudgyTurtle: Using Keystream to Encode and Encrypt

August¹,

Smith

2020

SN COMPUT. SCI.

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Stream cipher encryption works by modulo-2 adding plaintext bits to keystream bits, which are in turn produced by successively updating a finite-state machine initialized to a secret starting state. PudgyTurtle is a way to encode the plaintext in a keystream-dependent manner before encryption. Since it can use keystream from any stream cipher, PudgyTurtle functions somewhat like an encryption mode. The process begins by generating successive 4-bit groups of keystream ('nibbles') until one of them matches the current plaintext nibble to within one bit. The number of keystream nibbles required, as well as the nearness of this match, is then encoded into a variable-length codeword. Finally, this codeword is encrypted by modulo-2 addition to an equal amount of keystream. Compared to normal binary-additive stream ciphers, this process is less efficient (i.e., more time is required to generate extra keystream nibbles, and more space is needed for the codewords than for the plaintext). However, with this cost comes a benefit: PudgyTurtle resists time-memory tradeoff attacks better than standard stream encryption.

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Section: Stream-cipher Cryptanalysismentioning

confidence: 99%

PudgyTurtle: Using Keystream to Encode and Encrypt

August¹,

Smith

2020

SN COMPUT. SCI.

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“…A5/1 cryptography algorithm proposed to support data authentication and data encryption in second generation GSM mobile systems (2G-GSM) [10]. This algorithm has been adopted as encryption algorithm to secure data transmission operations in GSM systems.…”

Section: A A5/1 Algorithmmentioning

confidence: 99%

Mobile Technology Generations and Cryptographic Algorithms: Analysis Study

Jasim

Alshaikhli

2015

2015 4th International Conference on Advanced Computer Science Applications and Technologies (ACSAT)

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Nowadays, Mobile wireless technologies are becoming more significant and growing rapidly for better features and services. Latest Mobile technologies are expected to provide higher processing power, support high quality multimedia applications, offer reliable wireless connections, faster data transmission rates, and consume less power. At the same time, various mobile generations are susceptible to attack via eavesdropping and information leaking operations. Therefore, some cryptographic algorithms have proposed as confidentiality and integrity algorithms in different mobile generations, in order to prevent or mitigate these harmful operations. This paper provides analysis study of Mobile generations (From Mobile 1G to Mobile 4G) and cryptographic algorithms used in these generations. The study based on some factors like features, services, standards, and techniques which have adopted in these generations.

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“…Guessed a small number of bits do not seem enough to be able to make an attack. Mahalanobis and Shah [23] proposed a better version of the Guess and Determine attack against the A5/1 cipher in 2014; it required roughly 2 48.5 . First, 19 bits of register R1 are guessed using the 64 bits of the keystream available to cryptanalyst, and then the initial values of registers R1 and R2 are calculated in the second phase.…”

Section: Guess and Determine Attacksmentioning

confidence: 99%

Evolutionary approach to secure mobile telecommunication networks

Ghazli

Ali-Pacha²,

Said³

2021

IJEECS

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A series of encryption algorithms called A5 is used to secure mobile telephone communications, producing a pseudo-random sequence that will be exclusive OR (XORed) with the data flowing in the air interface in order to secure them. These algorithms are essentially composed of shift registers with linear feedback, controlled generally by a function or with another register in order to favor the randomness character of the keystream generated. Evolutionary algorithms are bioinspired calculation methods, whose principle is inspired by the theory of evolution, which consists in evolving a set of solutions to a problem given in order to find better results. This paper presents an improvement of the A5/1 algorithm by an evolutionary approach based on the use of particle swarm optimization algorithm (PSO) in order to limit some weaknesses and drawbacks found in the conventional A5/1 version, which have been cryptanalysed and several attacks have been published such as time memory trade off attacks and guess and determine attacks. Our technique does not alter the A5/1's architecture, but it does help to improve its shifting system by an evolutionary approach, which guarantees the quality of the keystream generated and makes it more complex and more secure.

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An Improved Guess-and-Determine Attack on the A5/1 Stream Cipher

Cited by 4 publications

References 10 publications

PudgyTurtle: Using Keystream to Encode and Encrypt

PudgyTurtle: Using Keystream to Encode and Encrypt

Mobile Technology Generations and Cryptographic Algorithms: Analysis Study

Evolutionary approach to secure mobile telecommunication networks

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