1 / 11

Fundamentals of Computer Security

Fundamentals of Computer Security. Cipher Challenge Feedback Rotor Cipher: The Enigma. Ciphertext 1.

blanca
Download Presentation

Fundamentals of Computer Security

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fundamentals of Computer Security Cipher Challenge Feedback Rotor Cipher: The Enigma CSCI 379 Fundamentals of Computer Security

  2. Ciphertext 1 WRQBK DGWRS UHSDU HWZRG LIIHU HQWVH TXHQF HVXVL QJWKH HQLJP DFLSK HUPDF KLQHR QHRIW KHVHL QYROY HGDJH UPDQD UPBHQ LJPDP DFKLQ HVXSS RVHGO BVHQG LQJPH VVDJH VIURP WKHUX VVLDQ IURQW WRKHD GTXDU WHUVL QJHUP DQBWK HRWKH UVHTX HQFHZ DVUHT XLUHG WRVLP XODWH LQWHU FHSWV LJQDO VIURP XERDW VZKLF KFRQW DFWHG DODUJ HFRQY RBLQP LGDWO DQWLF DQGVH QWFRQ WDFWV LJQDO VEDFN WRJHU PDQBX VLQJL WVHQL JPDPD FKLQH WKHFR QWDFW VLJQD OVIUR PWKHX ERDWV ZHUHV KRUWV LJQDO VVHQW EBUDG LRWKH BZHUH VKRUW WRDYR LGWKH UDGLR VLJQD OVEHL QJGLU HFWLR QIRXQ GIURP WKHXN WKHFR QWDFW VLJQD OVZHU HFRPS RVHGE BWKHX ERDWR SHUDW RUXVL QJDVK RUWVL JQDOF RGHER RNDQG WKHQH QFLSK HUHGR QKLVH QLJPD PDFKL QHWKH VLJQD OVZHU HRQOB WZHQW BWZRF KDUDF WHUVO RQJWK HVWRU BRIWK HILOP UHYRO YHVDU RXQGE OHWFK OHBSD UNEHL QJXQD EOHWR GHFLS KHUWK HXERD WVLJQ DOVEH FDXVH WKHJH UPDQQ DYBKD GFKDQ JHGWK HVKRU WZHDW KHUVL JQDOE RRNZK LFKWK HFRGH EUHDN HUVKD GEHHQ XVLQJ IRUFU LEVWK LVEOD FNRXW RFFXU UHGMX VWDVW KUHHO DUJHF RQYRB VZHUH SURFH HGLQJ IURPD PHULF DWRWK HXNLW ZDVLP SHUDW LYHWR ILQGR XWZKH UHWKH XERDW VZHUH VRWKD WWKHF RQYRB VFRXO GEHGL YHUWH GDZDB IURPW KHXER DWVLQ WKHIL OPEOH WFKOH BSDUN FRGHE UHDNH UVKDG QRLGH DKRZW RUHVW DUWEU HDNLQ JWKHQ DYDOH QLJPD FLSKH UFDOO HGVKD UNVRW KHBWX UQHGW RWRPM HULFK RZKRK DGEHH QWKHS HUVRQ ZKREU RNHLW LQWKH ILUVW SODFH MHULF KRZKR KDGVX IIHUH GDQHU YRXVE UHDNG RZQDQ GKDGE HHQVH QWEDF NWRFD PEULG JHIUR PEOHW FKOHB SDUNZ DVEUR XJKWE DFNWR WKHSD UNLQW KHILO PMHUL FKRUH DOLVH GWKDW WKHVK RUWVL JQDOV IURPX ERDWV ZKHQW KHBVL JKWHG DFRQY RBFRX OGEHX VHGWR GLVFR YHUWK HHQLJ PDVHW WLQJV DQGWK XVJHW EDFNL QWREU HDNLQ JWKHQ DYDOH QLJPD FLSKH UVKDU NZKDW WRQBK DGWRG RZDVW RUHFU HDWHW KHVKR UWVLJ QDOVV HQWIU RPWKH XERDW VRQPD NLQJF RQWDF WZLWK WKHFR QYRBV LQFHW KHVFU LSWHG SRVLW LRQRI WKHFR QYRBZ DVNQR ZQLQW KHQRU WKDWO DQWLF DQGLW VVSHH GDQGG LUHFW LRQWK LVFRX OGEHX VHGDV WKHFR QWHQW VRIWK HVKRU WVLJQ DOVLQ FHEOH WFKOH BSDUN KDGFD SWXUH GDFRS BRIWK HVKRU WVLJQ DOFRG HERRN EOHWF KOHBS DUNFR XOGDO VRUHF UHDWH WKHFR GHVXV HGWRG HVFUL EHWKH SRVLW LRQDQ GGLUH FWLRQ DQGVS HHGRI WKHFR QYRBW KLVJD YHZKD WEOHW FKOHB SDUNF DOOHG DFULE WKHJX HVVHG SODLQ WHAWR IWKHL QWHUF HSWHG FLSKH UPHVV DJHWR QBWKH QKDGW RGHFL GHRQD VHWWL QJIRU WKHHQ LJPDP DFKLQ HIRUW KDWGD BDQGX VHDUH DOPDF KLQHW RHQFL SKHUW KHVKR UWVLJ QDOWH AWVMX VWDVW KHXER DWRSH UDWRU ZRXOG KDYHG RQHWK HQEBV LPXOD WLQJW KHLQW HUFHS WLRQR IWKHV HVLJQ DOVDW DBVWD WLRQW KHWHO HSULQ WHURX WSXWF RXOGE HFUHD WHGZK LFKZR XOGKD YHDUU LYHGL QEOHW FKOHB SDUNW KHHVV HQFHR IEUHD NLQJW KHGDB VVHWW LQJVI URPWK HVHVK RUWVL JQDOV ZDVWK DWLQR UGHUI RUWKH PHVVD JHVWR EHVHQ WTXLF NOBWK HJHUP DQVXV HGDVL PSOHV BVWHP IRUWK HPHVV DJHVH WWLQJ WKLVP HVVDJ HVHWW LQJLV WKHSR VLWLR QVWRZ KLFKW KHHQL JPDZK HHOVD UHWRE HWXUQ HGWRG HFUBS WWKHP HVVDJ HDQGW KHHQL JPDRS HUDWR UMXVW ORRNH GXSDQ LQGLF DWRUP HVVDJ HVHWW LQJSD LULQK LVNER RNNHQ QJUXS SHQKH IWQUL QFOXG HGWKH LQGLF DWRUL QWKHP HVVDJ HKHDG LQJDQ GHQFL SKHUH GWKHV KRUWV LJQDO VWDUW LQJZL WKWKH ZKHHO VDWWK HPHVV DJHVV HWWLQ JEOHW FKOHB SDUNK DGFDS WXUHG DNERR NVRIU RPWKH LQGLF DWRUL QWKHP HVVDJ HKHDG HUFRX OGMXV WORRN XSWKH FRUUH VSRQG LQIRX QGWKH EDVHV HWWLQ JVRIW KHHQL JPDPD FKLQH IRUWK DWGDB ZKDWW RQBKD GWRGR ZDVWR DUUDQ JHWKD WWKHV HWRIP HVVDJ HVJHQ HUDWH GGLGL QIDFW SURGX FHDZR UNLQJ PHQXD QGWKD WZKHQ LWUDQ RQWKH ERPEH WKDWW KLVGL GJLYH WKHVH WWLQJ VIRUW KHGDB IURPW KHVFU LSWIR UWKHI LOPWR QBNQH ZZKHU HWKHF RQYRB ZDVLQ WKHQR UWKDW ODQWL FZKHQ LWZDV LQWHU FHSWH GEBWK HXERD WVWKH VFULS WDOVR JDYHW KHVSH HGDQG GLUHF WLRQR IWKHF RQYRB WKXVW RQBZD VDEOH WRJHQ HUDWH VXFFH VVLYH PHVVD JHVDV LIWKH BKDGF RPHIU RPWKH XERDW VDWYD ULRXV SRLQW VDORQ JWKHS DWKRI WKHFR QYRB English Caesar Cipher (affine m=1, a=3) CSCI 379 Fundamentals of Computer Security

  3. Ciphertext 2 YZUXQ HWYZE OBEHO BYNZW VGGBO BUYTB JDBUR BTDTV ULYQB BUVLP HRVEQ BOPHR QVUBZ UBZGY QBTBV UIZKI BWHLB OPHUH OPXBU VLPHP HRQVU BTDEE ZTBWK XTBUW VULPB TTHLB TGOZP YQBOD TTVHU GOZUY YZQBH WJDHO YBOTV ULBOP HUXYQ BZYQB OTBJD BURBN HTOBJ DVOBW YZTVP DKHYB VUYBO RBEYT VLUHK TGOZP DMZHY TNQVR QRZUY HRYBW HKHOL BRZUI ZXVUP VWHYK HUYVR HUWTB UYRZU YHRYT VLUHK TMHRF YZLBO PHUXD TVULV YTBUV LPHPH RQVUB YQBRZ UYHRY TVLUH KTGOZ PYQBD MZHYT NBOBT QZOYT VLUHK TTBUY MXOHW VZYQB XNBOB TQZOY YZHIZ VWYQB OHWVZ TVLUH KTMBV ULWVO BRYVZ UGZDU WGOZP YQBDF YQBRZ UYHRY TVLUH KTNBO BRZPE ZTBWM XYQBD MZHYZ EBOHY ZODTV ULHTQ ZOYTV LUHKR ZWBMZ ZFHUW YQBUB URVEQ BOBWZ UQVTB UVLPH PHRQV UBYQB TVLUH KTNBO BZUKX YNBUY XYNZR QHOHR YBOTK ZULYQ BTYZO XZGYQ BGVKP OBIZK IBTHO ZDUWM KBYRQ KBXEH OFMBV ULDUH MKBYZ WBRVE QBOYQ BDMZH YTVLU HKTMB RHDTB YQBLB OPHUU HIXQH WRQHU LBWYQ BTQZO YNBHY QBOTV LUHKM ZZFNQ VRQYQ BRZWB MOBHF BOTQH WMBBU DTVUL GZORO VMTYQ VTMKH RFZDY ZRRDO OBWAD TYHTY QOBBK HOLBR ZUIZX TNBOB EOZRB BWVUL GOZPH PBOVR HYZYQ BDFVY NHTVP EBOHY VIBYZ GVUWZ DYNQB OBYQB DMZHY TNBOB TZYQH YYQBR ZUIZX TRZDK WMBWV IBOYB WHNHX GOZPY QBDMZ HYTVU YQBGV KPMKB YRQKB XEHOF RZWBM OBHFB OTQHW UZVWB HQZNY ZOBTY HOYMO BHFVU LYQBU HIHKB UVLPH RVEQB ORHKK BWTQH OFTZY QBXYD OUBWY ZYZPA BOVRQ ZNQZQ HWMBB UYQBE BOTZU NQZMO ZFBVY VUYQB GVOTY EKHRB ABOVR QZNQZ QHWTD GGBOB WHUBO IZDTM OBHFW ZNUHU WQHWM BBUTB UYMHR FYZRH PMOVW LBGOZ PMKBY RQKBX EHOFN HTMOZ DLQYM HRFYZ YQBEH OFVUY QBGVK PABOV RQZOB HKVTB WYQHY YQBTQ ZOYTV LUHKT GOZPD MZHYT NQBUY QBXTV LQYBW HRZUI ZXRZD KWMBD TBWYZ WVTRZ IBOYQ BBUVL PHTBY YVULT HUWYQ DTLBY MHRFV UYZMO BHFVU LYQBU HIHKB UVLPH RVEQB OTQHO FNQHY YZUXQ HWYZW ZNHTY ZOBRO BHYBY QBTQZ OYTVL UHKTT BUYGO ZPYQB DMZHY TZUPH FVULR ZUYHR YNVYQ YQBRZ UIZXT VURBY QBTRO VEYBW EZTVY VZUZG YQBRZ UIZXN HTFUZ NUVUY QBUZO YQHYK HUYVR HUWVY TTEBB WHUWW VOBRY VZUYQ VTRZD KWMBD TBWHT YQBRZ UYBUY TZGYQ BTQZO YTVLU HKTVU RBMKB YRQKB XEHOF QHWRH EYDOB WHRZE XZGYQ BTQZO YTVLU HKRZW BMZZF MKBYR QKBXE HOFRZ DKWHK TZOBR OBHYB YQBRZ WBTDT BWYZW BTROV MBYQB EZTVY VZUHU WWVOB RYVZU HUWTE BBWZG YQBRZ UIZXY QVTLH IBNQH YMKBY RQKBX EHOFR HKKBW HROVM YQBLD BTTBW EKHVU YBSYZ GYQBV UYBOR BEYBW RVEQB OPBTT HLBYZ UXYQB UQHWY ZWBRV WBZUH TBYYV ULGZO YQBBU VLPHP HRQVU BGZOY QHYWH XHUWD TBHOB HKPHR QVUBY ZBURV EQBOY QBTQZ OYTVL UHKYB SYTAD TYHTY QBDMZ HYZEB OHYZO NZDKW QHIBW ZUBYQ BUMXT VPDKH YVULY QBVUY BORBE YVZUZ GYQBT BTVLU HKTHY HXTYH YVZUY QBYBK BEOVU YBOZD YEDYR ZDKWM BROBH YBWNQ VRQNZ DKWQH IBHOO VIBWV UMKBY RQKBX EHOFY QBBTT BURBZ GMOBH FVULY QBWHX TTBYY VULTG OZPYQ BTBTQ ZOYTV LUHKT NHTYQ HYVUZ OWBOG ZOYQB PBTTH LBTYZ MBTBU YJDVR FKXYQ BLBOP HUTDT BWHTV PEKBT XTYBP GZOYQ BPBTT HLBTB YYVUL YQVTP BTTHL BTBYY VULVT YQBEZ TVYVZ UTYZN QVRQY QBBUV LPHNQ BBKTH OBYZM BYDOU BWYZW BROXE YYQBP BTTHL BHUWY QBBUV LPHZE BOHYZ OADTY KZZFB WDEHU VUWVR HYZOP BTTHL BTBYY VULEH VOVUQ VTFMZ ZFFBU ULODE EBUQB GYUOV URKDW BWYQB VUWVR HYZOV UYQBP BTTHL BQBHW VULHU WBURV EQBOB WYQBT QZOYT VLUHK TYHOY VULNV YQYQB NQBBK THYYQ BPBTT HLBTT BYYVU LMKBY RQKBX EHOFQ HWRHE YDOBW HFMZZ FTZGO ZPYQB VUWVR HYZOV UYQBP BTTHL BQBHW BORZD KWADT YKZZF DEYQB RZOOB TEZUW VUGZD UWYQB MHTBT BYYVU LTZGY QBBUV LPHPH RQVUB GZOYQ HYWHX NQHYY ZUXQH WYZWZ NHTYZ HOOHU LBYQH YYQBT BYZGP BTTHL BTLBU BOHYB WWVWV UGHRY EOZWD RBHNZ OFVUL PBUDH UWYQH YNQBU VYOHU ZUYQB MZPMB YQHYY QVTWV WLVIB YQBTB YYVUL TGZOY QBWHX GOZPY QBTRO VEYGZ OYQBG VKPYZ UXFUB NNQBO BYQBR ZUIZX NHTVU YQBUZ OYQHY KHUYV RNQBU VYNHT VUYBO RBEYB WMXYQ BDMZH YTYQB TROVE YHKTZ LHIBY QBTEB BWHUW WVOBR YVZUZ GYQBR ZUIZX YQDTY ZUXNH THMKB YZLBU BOHYB TDRRB TTVIB PBTTH LBTHT VGYQB XQHWR ZPBGO ZPYQB DMZHY THYIH OVZDT EZVUY THKZU LYQBE HYQZG YQBRZ UIZX guesses: e=B, t=Y ? English Affine m=5, a=3 CSCI 379 Fundamentals of Computer Security

  4. Ciphertext 2 ============================================================= DECIPHERMENT USING ALPHABET alphabet.test============================================================= ----- ----B --B-- ----- ----- ---Y- ----- -Y-Y- ----- ----- ---B- ----- ----- ----- --Y-- ----- ----- ----- ----- ----- ----- -Y-BB -Y--- -Y--- ----- YY--- Y---- ----- YY--- ----- ----- ----- ---Y- ----- ----- ----- -Y--- ----- -Y--- ----- --Y-- ----- ----- --B-Y ----- Y---- ----- Y---- ----- ----- ----- ----- ----- ----- ----- ---Y- ----- ----Y ----- Y---- ----- ----- Y---- -Y--- ----- ----- ----- ----- Y---- -Y--- ----- ----Y ----Y ----Y ----- YY--- ----- ----- ----- Y---- ----- ----- ----- Y---- -Y--- ----- ----- ----- ----- ----- ----- ----- Y---- -Y--- ----B -Y--- ----- ----- B---- ---Y- ---Y- ---Y- ----- ----- ----- ----- ---B- ----- ---Y- ----- ----- ----- Y---- -Y--- ----- ----- ----- ----- ---Y- ----- -Y--- ----- ----- ----- --Y-- ----- ----- ---B- ----- ----- ----- ----B ----- ----- -Y--- --Y-- ---Y- ----- ----- ----- ----- ----- -Y--- ----- ---Y- ----- ----- ----- ----- ----- --Y-- ----- -Y--- ----- --Y-- -Y--- ----- ----- ----- Y--Y- ----- ----- ----- Y---- B---- ----- ----- ----- ----- ----- --Y-- B---- ----- ----- ----- ----- ----- Y---- Y---- ----- ----- Y---- ----- ----- ----- ----- ----- --Y-- ----- ----- ----- -B--- ----- ----- -Y--- ----- ----- ---Y- ----- ----- ----- ----- ----- --B-- ----- --Y-- --Y-- ----- ----- ----- ----- ----- ----- ----B --Y-- ----- ----- ----- ---Y- B---- ----- ----- ---Y- ----- ----- ---Y- ----- ----- ----- ---Y- ----- ----- ----- ----- ----- ----- B---- -Y--- ----- ----- ---B- ----- ----- ----- ----- ---Y- ----- ---Y- ---Y- ----Y ----- ----Y ----- ---Y- ----- ----- ----- ----- Y---- --Y-- ----- ----- --Y-- ----Y ----- -Y--- ----- ----- ----- ----- ----- ----- --B-- -Y--- ----- ----- ----- ---Y- ----- ----- --Y-- --Y-- ---YY ----- ----- ----- Y---- ----- ----- ----- ----- ----Y ----- --Y-- -B--- B-Y-- ----- ----- ----- -Y--- ----- ----- ----- ----- ----- YYB-- ----- ----- ----- -Y--- ----- Y---Y ----- ----- Y---- -Y--- -Y--- --Y-- ----- ----- -B--- ----- B---- ----B ----- -Y--- -Y--- ----- ----- ----- ----B ----- ----- Y---- ----- ----- --Y-Y ----- -Y--- ----- B-Y-- ----- ----- ----- ---YB ----- ----- ----- --Y-- ----- ----- ----- B---- ----- ----- ----- -YY-- B---- ----- ----- ----- -B--- --B-- ---YY ----- ----- ----- ----- ----- Y---- ----- ----- ----- ----- ----- ----- ----- Y---- ----- ----- ----- B---- --Y-- --Y-- ----- --Y-- Y--Y- ----- ---B- ----- ----- ----- ----- ----Y ----- ----- ----- ----B ----- ----Y -Y--- --Y-- --Y-- ----- ----- -B--- ----- -B--- ----- ----- ----- ----- ----- ----- ----- ----- ----- B---- ---YY ----- ----- ----- ----- YY--- ---Y- ----- -Y-Y- ---Y- ----Y --Y-- ----- ----- ----- --YY- --Y-- --Y-- ----- ----- ----- --Y-Y ---Y- -B--Y -Y--- ----- ---YY ---Y- ----- ---Y- -YY-- -Y--- ----Y ---B- Y---- -Y--- ----- ----- ----- ---Y- ----- ----- ----- ----B ----- -YY-- ----- ----- ----B ----- ---Y- ----- --B-- ----- ----- -YY-- -Y--- ---B- ----- -Y--- ----- ----B B---- ----- ----- ----- ----- ----- ----- -YY-- ----- ----- ----- B---- ----Y ----Y ----- Y---- ----- ----- ----- Y---- ---YY ---YY ----- ----- ----- B---- ----B ----- ----- -Y--- ----- ----- ----- ----- -YY-- ----- ----- ----Y ----- -B--- ----- YB--- ----- ----- --Y-Y ----- -Y--- ----- ----- ----- ----- ----- ----- ----- ----- --Y-- ----- ----- ----Y ----- -YY-- -Y--- ----- ----- ----- B---- ----- ----- ----- ----- ----- ----- ----- ----- ----- --Y-- ----- ---Y- ----- Y---- ----- ----- --Y-- -B--- ----- ----- ----- ----- ----- ----- --Y-- ----- ----- ----- ----- ----Y ----- --B-- ----- ----- -Y--- Y---B ---Y- ----- --YB- ----- ----- ----- ----- ----- ---Y- ----- Y---- ----- ----- Y---- YY--- --YY- --Y-Y ----- ----- ----- ----- ----- Y---- ----Y B---- Y---- ----B ----- ----- ---- YZUXQ HWYZE OBEHO BYNZW VGGBO BUYTB JDBUR BTDTV ULYQB BUVLP HRVEQ BOPHR QVUBZ UBZGY QBTBV UIZKI BWHLB OPHUH OPXBU VLPHP HRQVU BTDEE ZTBWK XTBUW VULPB TTHLB TGOZP YQBOD TTVHU GOZUY YZQBH WJDHO YBOTV ULBOP HUXYQ BZYQB OTBJD BURBN HTOBJ DVOBW YZTVP DKHYB VUYBO RBEYT VLUHK TGOZP DMZHY TNQVR QRZUY HRYBW HKHOL BRZUI ZXVUP VWHYK HUYVR HUWTB UYRZU YHRYT VLUHK TMHRF YZLBO PHUXD TVULV YTBUV LPHPH RQVUB YQBRZ UYHRY TVLUH KTGOZ PYQBD MZHYT NBOBT QZOYT VLUHK TTBUY MXOHW VZYQB XNBOB TQZOY YZHIZ VWYQB OHWVZ TVLUH KTMBV ULWVO BRYVZ UGZDU WGOZP YQBDF YQBRZ UYHRY TVLUH KTNBO BRZPE ZTBWM XYQBD MZHYZ EBOHY ZODTV ULHTQ ZOYTV LUHKR ZWBMZ ZFHUW YQBUB URVEQ BOBWZ UQVTB UVLPH PHRQV UBYQB TVLUH KTNBO BZUKX YNBUY XYNZR QHOHR YBOTK ZULYQ BTYZO XZGYQ BGVKP OBIZK IBTHO ZDUWM KBYRQ KBXEH OFMBV ULDUH MKBYZ WBRVE QBOYQ BDMZH YTVLU HKTMB RHDTB YQBLB OPHUU HIXQH WRQHU LBWYQ BTQZO YNBHY QBOTV LUHKM ZZFNQ VRQYQ BRZWB MOBHF BOTQH WMBBU DTVUL GZORO VMTYQ VTMKH RFZDY ZRRDO OBWAD TYHTY QOBBK HOLBR ZUIZX TNBOB EOZRB BWVUL GOZPH PBOVR HYZYQ BDFVY NHTVP EBOHY VIBYZ GVUWZ DYNQB OBYQB DMZHY TNBOB TZYQH YYQBR ZUIZX TRZDK WMBWV IBOYB WHNHX GOZPY QBDMZ HYTVU YQBGV KPMKB YRQKB XEHOF RZWBM OBHFB OTQHW UZVWB HQZNY ZOBTY HOYMO BHFVU LYQBU HIHKB UVLPH RVEQB ORHKK BWTQH OFTZY QBXYD OUBWY ZYZPA BOVRQ ZNQZQ HWMBB UYQBE BOTZU NQZMO ZFBVY VUYQB GVOTY EKHRB ABOVR QZNQZ QHWTD GGBOB WHUBO IZDTM OBHFW ZNUHU WQHWM BBUTB UYMHR FYZRH PMOVW LBGOZ PMKBY RQKBX EHOFN HTMOZ DLQYM HRFYZ YQBEH OFVUY QBGVK PABOV RQZOB HKVTB WYQHY YQBTQ ZOYTV LUHKT GOZPD MZHYT NQBUY QBXTV LQYBW HRZUI ZXRZD KWMBD TBWYZ WVTRZ IBOYQ BBUVL PHTBY YVULT HUWYQ DTLBY MHRFV UYZMO BHFVU LYQBU HIHKB UVLPH RVEQB OTQHO FNQHY YZUXQ HWYZW ZNHTY ZOBRO BHYBY QBTQZ OYTVL UHKTT BUYGO ZPYQB DMZHY TZUPH FVULR ZUYHR YNVYQ YQBRZ UIZXT VURBY QBTRO VEYBW EZTVY VZUZG YQBRZ UIZXN HTFUZ NUVUY QBUZO YQHYK HUYVR HUWVY TTEBB WHUWW VOBRY VZUYQ VTRZD KWMBD TBWHT YQBRZ UYBUY TZGYQ BTQZO YTVLU HKTVU RBMKB YRQKB XEHOF QHWRH EYDOB WHRZE XZGYQ BTQZO YTVLU HKRZW BMZZF MKBYR QKBXE HOFRZ DKWHK TZOBR OBHYB YQBRZ WBTDT BWYZW BTROV MBYQB EZTVY VZUHU WWVOB RYVZU HUWTE BBWZG YQBRZ UIZXY QVTLH IBNQH YMKBY RQKBX EHOFR HKKBW HROVM YQBLD BTTBW EKHVU YBSYZ GYQBV UYBOR BEYBW RVEQB OPBTT HLBYZ UXYQB UQHWY ZWBRV WBZUH TBYYV ULGZO YQBBU VLPHP HRQVU BGZOY QHYWH XHUWD TBHOB HKPHR QVUBY ZBURV EQBOY QBTQZ OYTVL UHKYB SYTAD TYHTY QBDMZ HYZEB OHYZO NZDKW QHIBW ZUBYQ BUMXT VPDKH YVULY QBVUY BORBE YVZUZ GYQBT BTVLU HKTHY HXTYH YVZUY QBYBK BEOVU YBOZD YEDYR ZDKWM BROBH YBWNQ VRQNZ DKWQH IBHOO VIBWV UMKBY RQKBX EHOFY QBBTT BURBZ GMOBH FVULY QBWHX TTBYY VULTG OZPYQ BTBTQ ZOYTV LUHKT NHTYQ HYVUZ OWBOG ZOYQB PBTTH LBTYZ MBTBU YJDVR FKXYQ BLBOP HUTDT BWHTV PEKBT XTYBP GZOYQ BPBTT HLBTB YYVUL YQVTP BTTHL BTBYY VULVT YQBEZ TVYVZ UTYZN QVRQY QBBUV LPHNQ BBKTH OBYZM BYDOU BWYZW BROXE YYQBP BTTHL BHUWY QBBUV LPHZE BOHYZ OADTY KZZFB WDEHU VUWVR HYZOP BTTHL BTBYY VULEH VOVUQ VTFMZ ZFFBU ULODE EBUQB GYUOV URKDW BWYQB VUWVR HYZOV UYQBP BTTHL BQBHW VULHU WBURV EQBOB WYQBT QZOYT VLUHK TYHOY VULNV YQYQB NQBBK THYYQ BPBTT HLBTT BYYVU LMKBY RQKBX EHOFQ HWRHE YDOBW HFMZZ FTZGO ZPYQB VUWVR HYZOV UYQBP BTTHL BQBHW BORZD KWADT YKZZF DEYQB RZOOB TEZUW VUGZD UWYQB MHTBT BYYVU LTZGY QBBUV LPHPH RQVUB GZOYQ HYWHX NQHYY ZUXQH WYZWZ NHTYZ HOOHU LBYQH YYQBT BYZGP BTTHL BTLBU BOHYB WWVWV UGHRY EOZWD RBHNZ OFVUL PBUDH UWYQH YNQBU VYOHU ZUYQB MZPMB YQHYY QVTWV WLVIB YQBTB YYVUL TGZOY QBWHX GOZPY QBTRO VEYGZ OYQBG VKPYZ UXFUB NNQBO BYQBR ZUIZX NHTVU YQBUZ OYQHY KHUYV RNQBU VYNHT VUYBO RBEYB WMXYQ BDMZH YTYQB TROVE YHKTZ LHIBY QBTEB BWHUW WVOBR YVZUZ GYQBR ZUIZX YQDTY ZUXNH THMKB YZLBU BOHYB TDRRB TTVIB PBTTH LBTHT VGYQB XQHWR ZPBGO ZPYQB DMZHY THYIH OVZDT EZVUY THKZU LYQBE HYQZG YQBRZ UIZX guesses: E=b, T=y ? Hmm… double Ys in the plaintext… guesses: E=b, T=s ? CSCI 379 Fundamentals of Computer Security

  5. Ciphertext 2 ============================================================= DECIPHERMENT USING ALPHABET alphabet.test============================================================= ----- ----B --B-- ----- ----- ---S- ----- -S-S- ----- ----- ---B- ----- ----- ----- --S-- ----- ----- ----- ----- ----- ----- -S-BB -S--- -S--- ----- SS--- S---- ----- SS--- ----- ----- ----- ---S- ----- ----- ----- -S--- ----- -S--- ----- --S-- ----- ----- --B-S ----- S---- ----- S---- ----- ----- ----- ----- ----- ----- ----- ---S- ----- ----S ----- S---- ----- ----- S---- -S--- ----- ----- ----- ----- S---- -S--- ----- ----S ----S ----S ----- SS--- ----- ----- ----- S---- ----- ----- ----- S---- -S--- ----- ----- ----- ----- ----- ----- ----- S---- -S--- ----B -S--- ----- ----- B---- ---S- ---S- ---S- ----- ----- ----- ----- ---B- ----- ---S- ----- ----- ----- S---- -S--- ----- ----- ----- ----- ---S- ----- -S--- ----- ----- ----- --S-- ----- ----- ---B- ----- ----- ----- ----B ----- ----- -S--- --S-- ---S- ----- ----- ----- ----- ----- -S--- ----- ---S- ----- ----- ----- ----- ----- --S-- ----- -S--- ----- --S-- -S--- ----- ----- ---H- S--S- ----- ----- ----- S---- B---- ----- ----- ----- ----- ----- --S-- B---- ----- ----- ----- ----- ----- S---- S---- ----- ----- S---- ----- ----- ----- ----- ----- --S-- ----- ----- ----- -B--- ----- ----- -S--- ----- ----- ---S- ----- ---------- ----- ----- --B-- ----- --S-- --S-- ----- ----- ----H ----- ----- ----- ----B --S-- ----- ----- ----- ---S- B---- H---- ----- ---S- ----- ----- ---S- ----- ----- ----- ---S- ----- ----- ----- ----- ----- ----- B---- -S--- ----- ----- ---B- ----- ----- -H--- ----- ---S- ----- ---S- ---S- ----S ----- ----S ----- ---S- ----- ----- ----- ----- S---- --S-- ----- ----- --S-- ----S ----- -S--- ----- ----- ----- ----- ----- ----- --B-- -S--- ----- ----- ----- ---S- ----- ----- --S-- --S-- ---SS ----- ----- ----- S---- ----- ----- ----- ----- ----S ----- --S-- -B--- B-S-- ----- ----- ----- -S--- ----- ----- ----- ----- ----- SSB-- ----- ----- ----- -S--- ----- S---S ----- ----- S---- -S--- -S--- --S-- ----- ----- -B--- ----- B---- ----B ----- -S--- -S--- ----- ----- ----- ----B ----- ----- S---- ----- ----- --S-S ----- -S--- -----B-S-- ----- ----- ----- ---SB ----- ----- ----- --S-- ----- ----- ----- B---- ----- ----- ----- -SS-- B---- ----- ----- ----- -B--- --B-- ---SS ----- ----- ----- ----- ----- S---- ----- ----- ----- ----- ----- ----- ----- S---- ----- ----- ----- B---- --S-- --S-- ----- --SH- S--S- ----- ---B- ----- ----- ----- ----- ----S ----- ----- ----- ----B ----- ----S -S--- --S-- --S-- ----- ----- -B--- ----- -B--- ----- ----- ----- ----- ----- ----- ----- ----- ----- B---- ---SS ----- ----- ----- ----- SS--- ---S- ----- -S-S- ---S- ----S --S-- ----- ----- ----- --SS- --S-- --S-- ----- ----- ----- --S-S ---S- -B--S -S--- ----- ---SS ---S- ----- ---S- -SS-- -S--- ----S ---B- S---- -S--- ----- ----- ----- ---S- ----- ----- ----- ----B ----- -SS-- ----- ----- ----B ----- -H-S- ----- --B-- ----- ----- -SS-- -S--- ---B- ----- -S--- ----- ----B B---- ----- ----- ----- ----- ----- ----- -SS-- ----- ----- ----- B---- ----S ----S ----- S---- ----- ----- ----- S---- ---SS ---SS ----- ----- ----- B---- ----B ----- ----- -S--- ----- ----- ----- ----- -SS-- ----- ----- --H-S ----- -B--- ----- SB--- ----- ----- --S-S ----- -S--- ----- ----- ----- ----- ----- ----- ----- ----- --S-- ----- ----- ----S ----- -SS-- -S--- ----- ----- ----- B---- ----- ----- ----- ----- ----- ----- ----- ----- ----- --S-- ----- ---S- ----- S---- ----- ----- --S-- -B--- ----- ----- ----- ----- ----- ----- --S-- ----- ----- ----- ----- ----S ----- --B-- ----- ----- -S--- S---B ---S- ----- --SB- ----- ----- ----- ----- ----- ---S- ----- S---- ----- ----- S---- SS--- --SS- --S-S ----- ----- ----- ----- ----- S---- ----S B---- S---- ----B ----- ----- ---- YZUXQ HWYZE OBEHO BYNZW VGGBO BUYTB JDBUR BTDTV ULYQB BUVLP HRVEQ BOPHR QVUBZ UBZGY QBTBV UIZKI BWHLB OPHUH OPXBU VLPHP HRQVU BTDEE ZTBWK XTBUW VULPB TTHLB TGOZP YQBOD TTVHU GOZUY YZQBH WJDHO YBOTV ULBOP HUXYQ BZYQB OTBJD BURBN HTOBJ DVOBW YZTVP DKHYB VUYBO RBEYT VLUHK TGOZP DMZHY TNQVR QRZUY HRYBW HKHOL BRZUI ZXVUP VWHYK HUYVR HUWTB UYRZU YHRYT VLUHK TMHRF YZLBO PHUXD TVULV YTBUV LPHPH RQVUB YQBRZ UYHRY TVLUH KTGOZ PYQBD MZHYT NBOBT QZOYT VLUHK TTBUY MXOHW VZYQB XNBOB TQZOY YZHIZ VWYQB OHWVZ TVLUH KTMBV ULWVO BRYVZ UGZDU WGOZP YQBDF YQBRZ UYHRY TVLUH KTNBO BRZPE ZTBWM XYQBD MZHYZ EBOHY ZODTV ULHTQ ZOYTV LUHKR ZWBMZ ZFHUW YQBUB URVEQ BOBWZ UQVTB UVLPH PHRQV UBYQB TVLUH KTNBO BZUKX YNBUY XYNZR QHOHR YBOTK ZULYQ BTYZO XZGYQ BGVKP OBIZK IBTHO ZDUWM KBYRQ KBXEH OFMBV ULDUH MKBYZ WBRVE QBOYQ BDMZH YTVLU HKTMB RHDTB YQBLB OPHUU HIXQH WRQHU LBWYQ BTQZO YNBHY QBOTV LUHKM ZZFNQ VRQYQ BRZWB MOBHF BOTQH WMBBU DTVUL GZORO VMTYQ VTMKH RFZDY ZRRDO OBWAD TYHTY QOBBK HOLBR ZUIZX TNBOB EOZRB BWVUL GOZPH PBOVR HYZYQ BDFVY NHTVP EBOHY VIBYZ GVUWZ DYNQB OBYQB DMZHY TNBOB TZYQH YYQBR ZUIZX TRZDK WMBWV IBOYB WHNHX GOZPY QBDMZ HYTVU YQBGV KPMKB YRQKB XEHOF RZWBM OBHFB OTQHW UZVWB HQZNY ZOBTY HOYMO BHFVU LYQBU HIHKB UVLPH RVEQB ORHKK BWTQH OFTZY QBXYD OUBWY ZYZPA BOVRQ ZNQZQ HWMBB UYQBE BOTZU NQZMO ZFBVY VUYQB GVOTY EKHRB ABOVR QZNQZ QHWTD GGBOB WHUBO IZDTM OBHFW ZNUHU WQHWM BBUTB UYMHR FYZRH PMOVW LBGOZ PMKBY RQKBX EHOFN HTMOZ DLQYM HRFYZ YQBEH OFVUY QBGVK PABOV RQZOB HKVTB WYQHY YQBTQ ZOYTV LUHKT GOZPD MZHYT NQBUY QBXTV LQYBW HRZUI ZXRZD KWMBD TBWYZ WVTRZ IBOYQ BBUVL PHTBY YVULT HUWYQ DTLBY MHRFV UYZMO BHFVU LYQBU HIHKB UVLPH RVEQB OTQHO FNQHY YZUXQ HWYZW ZNHTY ZOBRO BHYBY QBTQZ OYTVL UHKTT BUYGO ZPYQB DMZHY TZUPH FVULR ZUYHR YNVYQ YQBRZ UIZXT VURBY QBTRO VEYBW EZTVY VZUZG YQBRZ UIZXN HTFUZ NUVUY QBUZO YQHYK HUYVR HUWVY TTEBB WHUWW VOBRY VZUYQ VTRZD KWMBD TBWHT YQBRZ UYBUY TZGYQ BTQZO YTVLU HKTVU RBMKB YRQKB XEHOF QHWRH EYDOB WHRZE XZGYQ BTQZO YTVLU HKRZW BMZZF MKBYR QKBXE HOFRZ DKWHK TZOBR OBHYB YQBRZ WBTDT BWYZW BTROV MBYQB EZTVY VZUHU WWVOB RYVZU HUWTE BBWZG YQBRZ UIZXY QVTLH IBNQH YMKBY RQKBX EHOFR HKKBW HROVM YQBLD BTTBW EKHVU YBSYZ GYQBV UYBOR BEYBW RVEQB OPBTT HLBYZ UXYQB UQHWY ZWBRV WBZUH TBYYV ULGZO YQBBU VLPHP HRQVU BGZOY QHYWH XHUWD TBHOB HKPHR QVUBY ZBURV EQBOY QBTQZ OYTVL UHKYB SYTAD TYHTY QBDMZ HYZEB OHYZO NZDKW QHIBW ZUBYQ BUMXT VPDKH YVULY QBVUY BORBE YVZUZ GYQBT BTVLU HKTHY HXTYH YVZUY QBYBK BEOVU YBOZD YEDYR ZDKWM BROBH YBWNQ VRQNZ DKWQH IBHOO VIBWV UMKBY RQKBX EHOFY QBBTT BURBZ GMOBH FVULY QBWHX TTBYY VULTG OZPYQ BTBTQ ZOYTV LUHKT NHTYQ HYVUZ OWBOG ZOYQB PBTTH LBTYZ MBTBU YJDVR FKXYQ BLBOP HUTDT BWHTV PEKBT XTYBP GZOYQ BPBTT HLBTB YYVUL YQVTP BTTHL BTBYY VULVT YQBEZ TVYVZ UTYZN QVRQY QBBUV LPHNQ BBKTH OBYZM BYDOU BWYZW BROXE YYQBP BTTHL BHUWY QBBUV LPHZE BOHYZ OADTY KZZFB WDEHU VUWVR HYZOP BTTHL BTBYY VULEH VOVUQ VTFMZ ZFFBU ULODE EBUQB GYUOV URKDW BWYQB VUWVR HYZOV UYQBP BTTHL BQBHW VULHU WBURV EQBOB WYQBT QZOYT VLUHK TYHOY VULNV YQYQB NQBBK THYYQ BPBTT HLBTT BYYVU LMKBY RQKBX EHOFQ HWRHE YDOBW HFMZZ FTZGO ZPYQB VUWVR HYZOV UYQBP BTTHL BQBHW BORZD KWADT YKZZF DEYQB RZOOB TEZUW VUGZD UWYQB MHTBT BYYVU LTZGY QBBUV LPHPH RQVUB GZOYQ HYWHX NQHYY ZUXQH WYZWZ NHTYZ HOOHU LBYQH YYQBT BYZGP BTTHL BTLBU BOHYB WWVWV UGHRY EOZWD RBHNZ OFVUL PBUDH UWYQH YNQBU VYOHU ZUYQB MZPMB YQHYY QVTWV WLVIB YQBTB YYVUL TGZOY QBWHX GOZPY QBTRO VEYGZ OYQBG VKPYZ UXFUB NNQBO BYQBR ZUIZX NHTVU YQBUZ OYQHY KHUYV RNQBU VYNHT VUYBO RBEYB WMXYQ BDMZH YTYQB TROVE YHKTZ LHIBY QBTEB BWHUW WVOBR YVZUZ GYQBR ZUIZX YQDTY ZUXNH THMKB YZLBU BOHYB TDRRB TTVIB PBTTH LBTHT VGYQB XQHWR ZPBGO ZPYQB DMZHY THYIH OVZDT EZVUY THKZU LYQBE HYQZG YQBRZ UIZX guesses: E=b, T=s ? This “looks” better. We could go on guessing the hwole alphabet and seeing hot the plaintext looks, but there’s an alternative. CSCI 379 Fundamentals of Computer Security

  6. Review: The Affine Cipher Algorithm: for each letter P in the plaintext, compute a corresponding letter C of the ciphertext using the equation below. Caution: For key = (m,a), one should choose m such that GCD(m,26) = 1. PLAINTEXT ciphertext (key: m=5, a=8) CSCI 379 Fundamentals of Computer Security

  7. Solving for a and m Two unknows… one equation... Can you solve this??? The value of m was chosen so that gcd(m,26)=1. This guarantees that the is a multiplicative inverse for m and so this will decipher successfully to the plaintext. CSCI 379 Fundamentals of Computer Security

  8. Finding the multiplicative inverse What we want is to find some value of m* such that: Without any knowledge of number theory, we can try all values between 1 and 26 for m* in the above equation and see what works out. This value of m* can be used to decipher this affine cipher. CSCI 379 Fundamentals of Computer Security

  9. The Mechanization of Ciphers The Enigma Machine: Alan Scherbius, circa 1918. CSCI 379 Fundamentals of Computer Security

  10. The Mechanization of Ciphers The Enigma Machine: Alan Scherbius, circa 1918. CSCI 379 Fundamentals of Computer Security

  11. The Mechanization of Ciphers The Enigma Machine: Alan Scherbius, circa 1918. CSCI 379 Fundamentals of Computer Security

More Related