Blowfish A widely used block cipher Blowfish Designed

Blowfish A widely used block cipher Blowfish Designed by Bruce Schneier (1993) A variant of it (Twofish) was an AES finalist candidate 64-bit block size, 16-round Feistel network structure. Variable key size: 32-448 bits Key-dependent S-Boxes Blowfish Feistel Structure QuickTime and a

TIFF (Uncompressed) decompressor are needed to see this picture. Unlike a regular Feistel network, both sides are modified in each round: On 1st round, R1= L0 P1; L1= R0 F(L0 P1) http://en.wikipedia.org/wiki/Blowfish_(cipher) Blowfish round function

QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. Four 8-to-32 bits SBoxes are used. indicates XOR indicates addition mod 232 Mixing XOR and addition mod 232 complicates cryptanalysis http://en.wikipedia.org/wiki/Blowfish_(cipher)

Key schedule In Blowfish, the key schedule has two components Initialization of the S-boxes Initialization of the P-array (proper key schedule of a Feistel network) The entries of the P-array and S-boxes are first filled with the fractional part of the expansion of in hexadecimal. Key schedule (2) P1 = 243F6A88, P2 = 85A308D3, ..., S(4:254) =578FDFE3, S(4:255) =3AC372E6

The key K is XORED with the P-array, cycling over the key as needed. A 64-bit block of 0s is encrypted with the Blowfish algorithm and P1, P2 are replaced with the result, which is then encrypted again and substitutes P3, P4. This continues until all P-array and all S-Boxes entries are replaced. Key schedule algorithm Initialize P, S With ( frac() )16. XOR P, S with cyclically extended key. For (P, S) = (P1,P2, ..., S(4:254) , S(4:255)) Do Replace P1 , P2 Replace P3 , P4 ...

Replace P17 , P18 Replace S(1:0) , S(1:1) by Enc(P;S; 0) by Enc(P;S; P1||P2) by Enc(P;S; P15||P16) by Enc(P;S; P17||P18) ... Replace S(4:254), S(4:255) by Enc(P;S;S(4:252)||S(4:253)) Notes The S-boxes are read as simple lookup tables. For instance, if S2 is given the 8-bit input which is the binary expansion of the integer 127, then S(2:127) is

returned. 521 applications of Blowfish are required to install a new key: There are 18 P-array entries and 4x256 S-Box entries = total of 1042 entries. Each application of Blowfish replaces two of these entries. Blowfish facts Low key-agility and/or high memory demands makes Blowfish impractical in constrained environments. Small (64-bit) blocksize makes it insecure for

applications that encrypt large amounts of data with the same key (such as data archival, file system encryption, etc.) Implemented in SSL and other security suites. Blowfishs speed makes it an good choice for applications that encrypt intermediate amounts of data, such as typical of network communications (e-mail, file transfers).

No attacks on Blowfish are known that work on the full 16-round official version (certain attacks recover some information from versions with up to 14-rounds).

Recently Viewed Presentations

  • Sobeys Western Region & Borden Foods Canada

    Sobeys Western Region & Borden Foods Canada

    (weather at FIV can be different than where you are at). Rain outs will be posted on website and/or email sent out. If 5 or more holes are completed before signal to come in is given, rain check passes will...
  • Facts linked to child neglect - birmingham.gov.uk

    Facts linked to child neglect - birmingham.gov.uk

    Facts linked to child neglectChildren from low-income families are 4 times more likely to experience mental health problems than children from higher-income families.(Morrison Gutman et al., 2015) 75% of adults with a diagnosable mental health problem experience the first symptoms...
  • ORGANIC CHEMISTRY AN INTRODUCTION TO A guide for

    ORGANIC CHEMISTRY AN INTRODUCTION TO A guide for

    AN INTRODUCTION TO ORGANIC CHEMISTRY A guide for A level students KNOCKHARDY PUBLISHING CONTENTS WHICH COMPOUND IS IT? Elucidation of the structures of organic compounds - a brief summary Organic chemistry is so vast that the identification of a compound...
  • DIABETES y EMBARAZO

    DIABETES y EMBARAZO

    DIABETES y EMBARAZO Dra Gabuttti Clinica del sol 2009 Antes de la introducción de la insulina: -mortalidad materna 20% -mortalidad perinatal 60%.
  • Micro-Electro-Mechanical Systems (MEMS)

    Micro-Electro-Mechanical Systems (MEMS)

    Micro-Electro-Mechanical Systems are 1-100 micrometer devices that convert electrical energy to mechanical energy and vice-versa. The three basic steps to MEMS fabrication are deposition, patterning, and etching. Due to their small size, they can exhibit certain characteristics that their macro...
  • bjgp.org

    bjgp.org

    by Rachel Scantlebury, Gillian Rowlands, Stevo Durbaba, Peter Schofield, Kalwant Sidhu, and Mark Ashworth BJGP Volume 65(639):e649-e654 September 27, 2015 ©2015 by British Journal of General Practice Distribution of final dataset general practice A&E attendance rates per 1000 registered population.
  • Take note Mel Kinchant Academic Skills Adviser Widening

    Take note Mel Kinchant Academic Skills Adviser Widening

    Print off and read the lecture outline (slides or notes) If relevant, read your notes from the previous lecture. Look up scientific / technical terms and subject-specific jargon. Tune yourself into the topic by thinking of questions. Going in to...
  • The Communist Manifesto

    The Communist Manifesto

    Dialectical Materialism. Marxism. Marx's theories about society, economics and politics—collectively known as Marxism—hold that all societies progress through the dialectic of class struggle: a conflict between an ownership class which controls production and a lower class which produces the ...