Simple Des

Simple Des is a block cipher which encrypts an 9 bit block of plaintext using a 10 bit key and outputs an 8 bit block of ciphertext.This Simple Des presents of structure of Simple Des; basic fuctions of Simple Des; crypanalysis of Simple Des and some things else.

Nội dung trích xuất từ tài liệu:
Simple Des 6,03/( (66LPSOH (6 LV D EORFN FLSKHU ZKLFK HQFU\SWVDQ ELW EORFN RI SODLQWH[W XVLQJ D ELW NH\DQG RXWSXWV DQ ELW EORFN RI FLSKHUWH[W7KH HQFU\SWLRQ DOJRULWKP LQYROYHV nYH IXQFWLRQV H[HFXWHG LQ WKH IROORZLQJ RUGHU DQ LQLWLDO SHUPXWDWLRQ ,3 D IXQFWLRQ I. D VZLWFK IXQFWLRQ 6: WKDW VZLWFKHV WZRKDOYHV WKH IXQFWLRQ I. DJDLQ WKH LQYHUVH ,3 b RI SHUPXWDWLRQ ,3 6WHSV DQG XVH NH\V . DQG . UHVS ZKLFKDUH JHQHUDWHG YLD D NH\ JHQHUDWLRQ DOJRULWKP .(< *(1(5$7,21.H\ JHQHUDWLRQ LQYROYHV WKUHH IXQFWLRQV ZKLFKDUH DSSOLHG LQ D nYH VWHS VHTXHQFH LQ RUGHU WRSURGXFH WZR VXENH\V D SHUPXWDWLRQ 3 ZKLFK SHUPXWHV D ELWLQSXW D OHIW VKLIW RSHUDWLRQ DQ ELW SHUPXWDWLRQ WKDW SURGXFHV DQ ELWRXWSXW WKLV JLYHV WKH nUVW VXENH\ . DJDLQ WKH RXWSXW IURP VWHS LV VXEMHFWHGWR D VHFRQG GRXEOH OHIW VKLIW DQ ELW SHUPXWDWLRQ WKDW SURGXFHV D VHFRQG ELW RXWSXW WKLV LV WKH VHFRQG VXENH\ .6HYHUDO DOWHUQDWLYHV FRXOG KDYH EHHQ DSSOLHGOLNH HLWKHU XVLQJ D ODUJHU NH\ RU XVLQJ WZR LQGHSHQGHQW NH\V 6,03/( (6 KEY KEY GENERATIONENCRYPTION P10 DECRYPTION 10 Shift P10 IP IP^-1 5 5 P8 LS-1 LS-1 K_1 K_1 f_K f_K 5 5 Shift P8 SW SW K_1 K_2 P8 K_2 LS-2 LS-2 f_K f_K 5 5 P8 IP^-1 IP K_2 8 6758&785( 2) 6,03/( (66%R[HV 6 6 3HUPXWDWLRQ 3 „ 3HUPXWDWLRQ 3 „ 3HUPXWDWLRQ 3 „ %$6,& )81&7,216 2) 6,03/( (6(QFU\SWLRQ $OJRULWKP RQ .H\ . \ (. [ ,3 b r I. r 6: r I. r ,3 [ZKHUH . 3 6KLI W3 . . 3 6KLI W6KLI W3 .([DPSOH RI .H\ *HQHUDWLRQ NH\ . 3 6SOLW D /6KLIW D 0HUJH D 3 . E RXEOH /6KLIW E 0HUJH E 3 .7KXV WKH RULJLQDO ELW NH\ . LV EHLQJ XVHG WRJHQHUDWH WZR ELW NH\V . DQG . HFU\SWLRQ $OJRULWKP RQ .H\ . [ . \ ,3 b r I. r 6: r I. r ,3 \7KH IXQFWLRQV DUH GHnQHG DV IROORZV ,QLWLDO 3HUPXWDWLRQ „ , 3 ,QYHUVH RI WKH ,QLWLDO 3HUPXWDWLRQ „ b , 3 1RWH WKDW ,3 ,3 b[ ,3 b,3 [