DocumentCode :
1456605
Title :
Word-based FCSRs with fast software implementations
Author :
Lee, Dong Hoon ; Park, Sangwoo
Author_Institution :
Electron. & Telecommun. Res. Inst., Daejeon, South Korea
Volume :
13
Issue :
1
fYear :
2011
Firstpage :
1
Lastpage :
5
Abstract :
Feedback with carry shift registers (FCSRs) over 2-adic number would be suitable in hardware implementation, but they are not efficient in software implementation since their basic unit (the size of register cells) is 1-bit. In order to improve the efficiency we consider FCSRs over 2 -adic number (i.e., FCSRs with register cells of size ℓ-bit) that produce ℓ bits at every clocking where ℓ will be taken as the size of normal words in modern CPUs (e.g., ℓ = 32). But, it is difficult to deal with the carry that happens when the size of summation results exceeds that of normal words. We may use long variables (declared with ´unsigned _int64´ or´unsigned long long´) or conditional operators (such as ´if statement) to handle the carry, but both the arithmetic operators over long variables and the conditional operators are not efficient comparing with simple arithmetic operators (such as shifts, maskings, xors, modular additions, etc.) over variables of size ℓ-bit. In this paper, we propose some conditions for FCSRs over 2 -adic number which admit fast software implementations using only simple operators. Moreover, we give two implementation examples for the FCSRs. Our simulation result shows that the proposed methods are twice more efficient than usual methods using conditional operators.
Keywords :
carry logic; circuit feedback; cryptography; shift registers; 2 -adic number; CPU; arithmetic operator; conditional operator; feedback with carry shift register; register cells; software implementation; word-based FCSR; Clocks; Cryptography; Generators; Manganese; Shift registers; Software; Feedback with carry shift register (FCSR); software implementation; stream cipher;
fLanguage :
English
Journal_Title :
Communications and Networks, Journal of
Publisher :
ieee
ISSN :
1229-2370
Type :
jour
DOI :
10.1109/JCN.2011.6157244
Filename :
6157244
Link To Document :
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