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ac III pnopaece aop aa 11 Maeaece oco 11.1 Teop opa Copeea eop opa epe a oyoaa 1948 oy oo . eoo (Claude Elmwood ...

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oe, oao, ec e opoc o o, eceo aop ec pyo, a o o, aco o o o pye. Ec e xaae oo ooo eea, o aop e opaye pyy, o ooe poae o - cacec oop - poco oepe pee. Paoa a DES oaaa, o DES oe ae o py. Cyecye ae p epecx opoco o oypye, oyaeo p poa DES. Coep oa oeco, o ec, e opaye oa pyy? coa, e eeppye oa y eoopa oa oepa poa (e eppoa) oecey y? Ec a, acoo a caa opoa aa oa?

e cceoa ec oea pocpaca e eopeecoo cp pyo co, a p e ya pecae coo aoy pay po pocpaca e.

Cae u B xopoe oo pe ce oaoo c. Oo e poe p aope c a oeco cax e, ao a DES. Bepooc cyao pa o x oe aa, ao eo poep p eoxooc opoc. Oao, oa cae oy aec oa, ec o p coyec a ooapaea x-y (c. pae 18.11).

cmouocm uepeuaoy u ueoy punmoaauy cceoae epeaoo eoo poaaa aeo poco eop poepo a xopoeo ooo pa. Aop IDEA e oe epeao, ooee ocoo e xa paepc [931]. O yepa, o oo coaa oe p, ycoe cp aoo a. Peyao oooo poepoa ec IDEA [931]. oee o oe o opaoao [1181, 1182], oa aca Hep (Kaisa Nyberg) apc yce (Lars Knudsen) oaa, a coaa o e p oayeo eoace o ooe epeaoy poaay. a eop a pa c pea a epea cx opo [702, 161, 927, 858, 860] ace epea [860]. a ec, o epea cx opo pe oo pa c a co ao, o ac e epea pepaco oec c epeaa.

e poaa oee, o ce ee coepecyec. opeee o acca e [1019] ecox pe [811, 812]. Ee oo pacpee poaaa oo a [1270]. B [938] a pepa oa oe epea e poaa oo cp. oa eco, aa eoa poepoa coe pooco oo cp.

yce oc eoopoo ycexa, paccapa eoope eoxoe (o, ooo, e ocaoe) pep oo, o o aa paec eoac ce ecea - po, ycox a epeaoy, a eoy poaay [857]. Hep e eoo poaaa aao o epeao epeao poaae [1180].

ocaoo epeco aec oceoc epeaoo eoo poaaa. a o ceoc caoc oeo a p papaoe eo coa xopox epeax xapa e pc ex pe [164, 1018], a p papaoe pep poepoa, oeceaeo ycooc aopo oo a cp [307]. oa oo eeco, ya aee o apaee cceoa. aaa e papaoa cpae poepoa aopa, ocoay a epe ao eo poaae [402].

poemupoaue S-oo Ca oca cee ecea - ocoeo x ycooc epeaoy eoy p oaay - eocpeceo caa c x S-oa. o oc po ooa cceoa, o e op a ye xopo S-o.

S-o - o poco ocaoa: oopaee m-ox xoo a n-oe xo. Paee yoa o oo oo ae oopae 64-ox xoo a 64-oe xo, aa aa pecaa coo S-o paepo 64*64 a. S-o c m-o xoo n-o xoo aaec m*n o S-oo. S-o oo c ece ee ece aope, eo o oecea eoacoc ooo pa. B oe cyae e S-o oe, e ye.

B DES oce pax 6*4-ox S-oo. B Khufu Khafre ece 8*32-o S-o, LOKI 12*8-o S-o, a Blowfish CAST 8*32-oe S-o. B IDEA S-oo o cy ec yoee o oy, o 16*16-o S-o. e oe S-o, e pyee oapy cacece ooe, ye cp c cooae o epeaoo, o eoo poaaa [653, 729, 1626]. poe oo, xo cyae S-o oo e oa c o pe ycooc epeaoy eoy poaay, ce S-o ee a cpe S-oo oeo pa epa. oco cyax S-oo ee, epoe oaa co ycooc e oy poaay - c yeee ca xox o a o caec eeo [1185, 1186, 1187].

Paep m aee paepa n. eee paepa n cae eoc epeaoo poa a a, o aeo oae eoc epeaoo poaaa. eceo, ec n2m-m, o aepa cyecye ea acoc xox xox o S-oa. ec n2m, o ea acoc cyecye oo xox o [164].

aeo ac pao o poepoa S-oo ec yee oecx y [94, 1098, 1262, 1408]. oecee eoacoc ye y, coyee S-oax, o oea op e ee yco. O e o e, a, ae e a [9, 1177, 1178, 1188]. oeco ye e oo caacpoa, e oo ax oppe ey pa oa o. p ee a poooo oo xooo a xoe o ec ce eaco. pep poepoa ae c a c yee y a: y, oope, a oe oaao, c oao ee . Xo o opeee poco ececeo, x yee oe eeo [1344, 1216, 947, 905, 1176, 1271, 295, 296, 297, 149, 349, 471, 298].

Oe a coco pecaec a e: coo xox o S-oa eec p ee eoopoo ooeca xox o. Hepyo aa yex y yco, oee oopx oeceae opeee a e, o poepoae ax y ec oee coo aae. Cpo a pep (strict avalanche criteria, SAC) oeceae, o c e ee ooo xooo a eec poo ooa xox o [1586]. C. ae [982, 571, 1262, 399]. B oo pao pep paccapac epax ye opa [1640].

Hecoo e aa popa peo pa S-o a, o aa pacpeee pa aoo S-oa a oopoo. o oeceo ycooc epeaoy poa a y a ce caa epeao a o oeo ae [6, 443, 444, 1177]. pepo aoo poepoa ec LOKI. Oao ao oxo oa cococye epeaoy poaay [172]. eceo, y oxoo ec poae acaoo epeaa. ao (Kwangjo Kim) y pepe poepoa S-oo [834], oxox a pep poep o a S-oo DES.

Bop xopox S-oo - e poca aaa, cyecye oeco pax e, a ye cea o. Moo e epe ax oxoa.

1. Cyao pa. co, o eoe cyae S-o eeoac, o oe cyae S-o oy oaac ocaoo xopo. Cyae S-o c oce oee xoa oc a oo c [1186, 1187]. Ee ye 12-oe S-o. cooc S-oo opacae, ec o oopeeo c cya, ac o a. B IDEA coyc oe ace o a S-o.

2. Bpa poep. B eoopx pax coca S-oo, eeppoax cya opao, poepc. pep aoo oxoa coepac [9, 729].

3. Papaoa pyy. p o aeaec aapa coyec pae eaeo: S-o coac c cooae yx peo. ap pee (Bart Preneel) a, o "... eop e ec epece pep eocao [ opa yex y S-oo]...", o "... e oxo ceae pep poepoa" [1262].

4. Papaoa aeaec. S-o coac cooec c aeaec aoa, ooy o oaa apapoao aeoc o ooe epeaoy eoy poaay, a ae xopo y coca. pepac pep aoo oxoa oo a [1179].

Cyecye p po oe "aeaec" "pyo" oxo [1334], o peao, o oy, oyppy cyao pae S-o S-o c opeee coca. oeo pey e co oceeo oxoa ec oa po ecx eoo cp - epeaoo eoo poaaa - o oeceaea oxoo cee a o eecx eoo cp ae eeca. Papaoa DES o eco o epeao poaae, eo S-o opoa cooecy opao. Copee ceo, o eo poaae o e a, S o DES oe ca o ooe aoy cocoy cp [1018]. Cyao pae S-o DES caee po epeaoo poaaa, o cee po eoo poaaa.

C pyo copo cyae S-o oy e oa o ooe a cocoa cp, o o oy ocaoo o , ceoaeo, ocaoo ae. poe oo, o, copee ceo, yy ocaoo yco po eecx cocoo cp. Cop ce ee , o o e aec, o S-o o a o, acoo o ooo, cya a ce o a.

poemupoaue ooo upa poepoa o p epyo. Ec paccapae 64-o o p a epecao y 64-ox ce, co, o o ce epecao eoac. Tpyoc coco poepoa ooo pa, oop e oo eoace, o ae oe eo oca poco peaoa.

eo oo cpoepoa o p, ec coyee a, ocaoy paee S oo 48*32. Tpyo cpoepoa eeoac apa DES, ec copaeec cooa e ao. p e a 512 o e co ecooc o o, e ao-o ace o a o eapoc.

14.11 cnooae ooanpaex x-y C poc cocoo cooa poa ooapaey x-y ec x poae peyeo oa poeca, oeeoo c o, a ae oee XOR peyaa c e y oo opoo eca:

Ci = Pi H(K, Ci-1) Pi = Ci H(K, Pi-1) caoe y oa pao e peyaa ooapaeo x-y. o cy o po cooa ooapaeo x-y a ooo pa pee CFB. p oo aaoo ocpy oo cooa ooapaey x-y pee OFB:

Ci = Pi Si;

Si = H(K, Ci-1) Pi = Ci Si = H(K, Ci-1) Haeoc ao cxe opeeec eoacoc ooapaeo x-y.

Karn o eo, opee o apo (Phil Karn) op coooo cooa, coae opa aop poa opeeex ooapaex x-y.

Aop paoae c 32-ao oa opoo eca poeca. a a oe pooo, xo opeeee e oee e opex ooapaex x y. ooapaex x-y MD4 MD5 ye ceo oxo 96-aoe .

poa caaa paee op ec a e 16-aox oo: Pl Pr. ae paee a e 48-aox oo : Kl Kr.

P= Pl, Pr, K = Kl, Kr oae Kl Pl oe xpoae ooapaeo x-ye, ae oe XOR pey aa c Pr, oya Cr, pay ooy poeca. ae, oae Kr Cr oe xpoae ooa paeo x-ye. Boe XOR peyaa c Pl, oya Cl. Haoe, oee Cr Cl, oya poec.

Cr = Pr H(Pl, Kl) Cl = Pl H(Cr, Kr) C = Cl, Cr eppoa poco eppye poecc. oae Kr Cr, oe xpoae XOR pe yaa c Cl, oya Pl. oae Kl Pl, oe xpoae XOR peyaa c Cr, oya Pr.

Pl = Cl H(Cr, Kr) Pr = Cr H(Pl, Kl) P = Pl, Pr Oa cpyypa Karn coaae c cpyypo oeca pyx ox aopo, paccopex o paee. aopa oo a aa, a a eo cooc opeeec ooapaeo x ye. A, a a coyec oo a xo x-y, o e oe pacp ae p oo cp c pa op eco, ec, oeo, eoaca coyea ooapaea x-y.

Luby-Rackoff Ma (Michael Luby) ap Pao (Charles Rackoff) oaa, o Karn e ec eoac [992]. Paccop a ooox cooe: AB AC. Ec poaay ec op ec poec epoo cooe, a ae epa ooa opoo eca opoo cooe, o o oe eo c ce opoe cooee. Xo aoe cpe c ec op eco paoae oo p opeeex ycox, oo pecae coo ay poey eoacoc aopa.

Ee yaec ea p oo pexaoo aopa poa [992,1643,1644]. O coye p pax x-y: H1, H2 H3. aee cceoa oaa, o H1 oe coaa c H2, H oe coaa c H3, o e oopeeo [1193]. poe oo, H1, H2 H3 e oy ocoa a epa x oo o e aoo y [1643]. B o cyae p yco, o H(k,x) ee ce a ceocy aa y, pexaa epc cey opao:

(1) Paee a e oo: Kl Kr.

(2) Paee o opoo eca a e oo: L0 R0.

(3) Oee Kl L0 oe xpoae. Boe XOR peyaa xpoa c R0, oya R1:

R1= R0 H(Kl, L0) (4) Oee Kr R1 oe xpoae. Boe XOR peyaa xpoa c L0, oya L L1 = L0 H(Kr, R1) (5) Oee Kl L1 oe xpoae. Boe XOR peyaa xpoa c R1, oya R2:

R2= R1 H(Kl, L1) (6) Oee L1 R2, oya cooee.

up pamoo coepau cooeu p paoo coepa cooe(Message Digest Cipher, M DC), opee epo yao (Peter Cutmann) [676], pecae coo coco pepa ooapaee x-y o p, paoa pee CFB. p paoae o ae cpo, a x-y, o pae epe a coo e eoace. Ocaac ac oo paea peoa ae aoco c ao 18.

X y, apep MD5 SHA, coy 512-o eco o peopaoa xo o o ae (128 o MD5, 160 o SHA) peya oo e paepa. o peopaoae eopa o, o pepaco oxo pea CFB: poa, eppoa coyec oa a e oepa.

Paccop MDC c SHA. MDC coye 160-o o 512-o . coyec oo e x-y, oa aece peeo x-ae epec xoo o opoo eca (160 o), a 512-o xo x-y pae po a (c. Pc 14.5). Oo p cooa x y xpoa eoopoo xoa 512-o xo eec p xpoa aoo ooo 512 ooo oa. Ho ao cyae 512-o xo caoc eee o.

MDC oo cooa c o ooapaeo x-ye: MD4, MD5, Snefru, .. O ea a eoa oe coepeo ecao cooa e yoo oa yoo eo yoo [676 ].

Oao o e ep y cxey. Moo oopa ao coco oa, a poocoe oopoy x-y e a paccaa. X-y e oa pooco cp c pa op eco, oa poaa pae eoope aae 160-oe ae, oyae x "apoa" o e e 512-o "o" oyec oye eoopo opa o coyeo 512-oo e. Ta a papao x-y e o ecooc o ao oooc, ca a p eoac o ooe peeoy cocoy cp - e y a e.

eonacocm upo, ocoax a ooanpaex x-yux Xo ocpy oy eoac, o ac o coyeo ooapaeo x y. Xopoa ooapaea x-y e oaeo ae eoac aop poa.

Cyecy pae popaece peoa. Hapep, e poaa ecoee po ooapaex x-yx, o ecee po aopo poa. Ooapaea x y, aa a SHA, oe oaa opeee e xapaepca, oope, e a ee eoacoc a ooapaeo x-y, oy cea eeoac ee cooae ao aope poa, a MDC. Me eeco o ax peyaax poaaa cooa o peo ooapaeo x-y aece ooo pa. pee e cooa x oec poee oooo aaa.

o cooe X- X Bxooe Bxooe y y aee aee Op poec ec (a) X-y (b) X-y a o p pee CFB Pc. 14-5. p paoo coepa cooe (MDC).

14.12 Bop ooo aopa o oe pyoe peee. DES o aepa eeoace p cooa po paec e x epa, ec oo e pyee o o oe ae op ax. Booo o a o p oa eox po oo-y pyoo, o cope o ec. Ma cp a DES pyo co copo cay o apay ce opaa.

peoee xao ace o a S-o DES yy eoac eee o pae epe e cox e, oe a cee cooa po cax xopoo oeceex poo.

Ec eoxoa eoacoc oa oeceea a ece, oacaeec poaa e cx yc paec ex epa, ocoyec po DES c pe eac a.

Heeoe pye aop. Me pac Blowfish, ooy o o cp, ooy o eo p y a. Heoxo 3-WAY, ooo ce ope c OCTo. poea ocoeoa o-y c o co o, o NSA o aepa oaae aopo ex poaaecx peo, oope o cx op acepee, e a, ae aop oy cp. B Ta. 14.3 cpae p e e peee coooe eoopx aopo.

Mo aop - IDEA. Eo 128-o coea c ycooc oeec cpeca poaaa - o co oeo eoo eoo yca oy aopy. o aop aapoac pa pya, ax cepex aea e o oyoao. B ocyce eoax poaaecx popo ceo ca a IDEA.

Ta. 14-3.

Copoc poa eoopx ox po a i486SX/33 M Aop Copoc poa Aop Copoc poa (a/c) (a/c) Blowfish (12 ao) 182 MDC (c MD4) Blowfish (16 ao) 135 MDC (c MD5) Blowfish (20 ao) 110 MDC (c SHA) DES 35 NewDES FEAL-8 300 REDOC II FEAL-16 161 REDOC III FEAL-32 91 RC5-32/8 OCT 53 RC5-32/12 IDEA 70 RC5-32/16 Khufu (16 ao) 221 RC5-32/20 Khufu (24 ao) 153 SAFER (6 ao) Khufu (32 ao) 115 SAFER (8 ao) Luby-Rackoff (c MD4) 47 SAFER (10 ao) Luby-Rackoff (c MD5) 34 SAFER (12 ao) Luby-Rackoff (c SHA) 11 3-Way Lucifer 52 Tpoo DES

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