MODES OF OPERATION

2-D Encryption Mode Ahmed A. Belal Moez A. Abdel-Gawad

Q2Q2 Q1Q1 Q 16 2DEM P = Each P i = P 16 P2P2 P1P1 Each Q i = Set Each R i = S2S2 S1S1 S 16 R 16 R2R2 R1R1 Each S i = Then C = Where Each C i = KKK KKK

2DEM BPR = Blocks Per Row P91P91 P 12 1 P31P31 P61P61 BPR = 1 P11P11 BPR = 2 BPR = 4 BPR = 3 P12P12 P21P21 P22P22 P31P31 P32P32 P41P41 P42P42 P51P51 P52P52 P61P61 P62P62 P71P71 P72P72 P81P81 P82P82 P11P11 P12P12 P31P31 P32P32 P21P21 P22P22 P41P41 P42P42 P51P51 P52P52 P71P71 P72P72 P61P61 P62P62 P81P81 P82P82 P11P11 P12P12 P41P41 P42P42 P21P21 P22P22 P51P51 P52P52 P32P32 P62P62 P71P71 P72P72 P 10 1 P 10 2 P81P81 P82P82 P 11 1 P 11 2 P92P92 P 12 2 P11P11 P12P12 P51P51 P52P52 P21P21 P22P22 P61P61 P62P62 P31P31 P32P32 P71P71 P72P72 P41P41 P42P42 P81P81 P82P82

2DEM Works great with images BPR value and Key needed Resistance to certain attacks due to interleaving

Accumulated Block Chaining Mode Lars R. Knudsen

ABC Where h(x) = x or h(x) = x <<1 P1P1 P2P2 P3P3 PmPm H0H0 C0C0 H1H1 K C1C1 h(x) H2H2 K C2C2 h(x) H3H3 K C3C3 HmHm K CmCm

ABC Has infinite error propagation Authentication is not intended as part of mode Infinite error propagation provides more diffusion 2 initial vectors and Key needed The mode acts more like a giant block cipher Resists birthday attacks

Key Feedback Mode Johan Håstad Mats Näslund

KFB P K K1K1 RBRmBRm m bits Where R is m x n matrix and B is multiplication of R and K i mod 2 K1K K2K2 RBRmBRm m bits K2K K3K3 RBRmBRm m bits K L-1 KLKL RBRmBRm m bits

KFB Random Bit Generator Initial matrix, constant, and Key needed Does not assume that the block cipher is a pseudo- random permutation Does assume that one or more iterations of the block cipher (with varying keys and a fixed plaintext) are hard to invert Under this assumption, the KFB outputs are pseudo-random

Propagating Cipher Feedback Mode Henrick Hellström

PCFB P0P0 P1P1 PLPL IV K T mod 2 m C0C0 >> m << n-m K T mod 2 m C1C1 >> m << n-m K T mod 2 m CLCL Each P i is m bits longL = # of plaintext blocks P = (P 1, P 2, … P L ) n = number of bits in the key m = number of bits in each plaintext block

PCFB Has two way error propagation Claims that no additional authentication is needed Authentication mode was proposed Initial vector and Key needed

AES-hash Bram Cohen Ben Laurie

AES-hash P is padded with 0’s to the next odd multiple of 128 bits and then appended with the 128-bit Big Endian encoding of the number of bits in the original file. Each P i is 256 bits H0H0 P1P H0H0 H1H1 P2P H2H2 P3P H3H3 PmPm HmHm HmHm HmHm HASH

AES-hash Uses AES-256 Variation of the Davies-Meyer hash construction Using last step prevents an adversary from creating a new hash for a related message Only the Key is needed

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