TRƯỜNG ĐẠI HỌC SƯ PHẠM HÀ NỘI
KHOA CÔNG NGHỆ THÔNG TIN
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NGHIÊN CỨU KHOA HỌC
Đề tài:
TÌM HIỂU MẬT MÃ HỌC VÀ ỨNG DỤNG TRONG XÁC THỰC CHỮ
KÝ ĐIỆN TỬ
PGS.TS.Vũ Đình Hòa
Trịnh Mai Hương
Hà nội ,2008
Mục lục
Lời nói đầu..............................................................................................................4
Chương 1.Tổng quan về mật mã học....................................................................5
1.1.Lịch sử phát triển của mật mã........................................................................5

 !"#$%
&#!''(()
*
 +,-$.,/0#%
123456
&789* 
&:;<;<5<5<=##>?@A
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 
& * 1
Chương 2.Hệ mật mã cổ điển..............................................................................28
LM5J,5# )
 LNOOJ 6
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 b$#@CS#J,,5J)1
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M?#@*<#e$'f$;D5gg,M;dGhW.Mi#
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Lời nói đầu
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Chương 1.Tổng quan về mật mã học
1.1.Lịch sử phát triển của mật mã
9;+;I93,/m;@a5<!#Ee9
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0<R55H,]'$5H<CW'E0s=M
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1.1.5.Mật mã học hiện đại
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:Communication Theory of Secrecy SystemsA#E,5 Bell System Technical
Journalk!E,5C‚$D5-’J99k;+"5‹,5$IH#
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Bureau of StandardskY’A:9;Y(!AHG\fc$^BjsW<(’
:International Business MachinesA#@#t;+#.-‹

,$^<]EWE=Bj•#Œ#;9;.?_$5C
lIC\a;<#V
!'#U5H;a6X%HI9}>+E?.5H@'#
;<5<f\?G\#9;D5-I5
2I]9;WG-D5G;'E?#:New
Directions in CryptographyAD5—OJ9BOOJ;5#LJ995’;'
$+E?EE;;fUE8E-CI5
28<9;+G'Cc5#\_$<'+^f?G\#
H^fE8E-CI5H;Is9;#5CI5BOOJkLJ995
:Diffie-Hellman key exchangeA’;'>C]],E#eU
"D5+9E$I5H$@5CI5G^-
cU:asymmetric key algorithmsA
!#"C„;<He$'$I5*f$9;.
$CI5-cU:symmetric key algorithmsAH#I\"/;
"E\=$+CI5HUCI5=#$H;
\5"f$E\.G]fCI5;<!^\<?=#
''((HC\M5J,5#;NG5,H;fG\^;IHC\e$'
-s=#,$-_$#@93,/.5f$$+f9*;<
2?HCI5D5+]9;,:codebookAH;9;lE\
sE8E-;.@+G]?
B$e$5HCI5•+-<^'E\
s#5.5G5W99*Gh+E?U5;;
^<H#C,/0-:$."s=9;•W_$5+
C5;•AH]0Gh,/0+"5<
+dE;9$sCI5;5<Gh+dECI55<HdGh$+dE
Šd-dH5<Gh+GV8$5#$;P^f;<
5G5"scJ9;“H;I5I#t+e
CW_$\9SsC,-9s"55a9H5<C"
5CW>C5;#5CI5.5Hd9pE\905<
@5CI5k+I_$J#C9;M0

;'$uG'],-@#^CI@#5 m5,-G5e$B
.d]D5;+f$He$'CI5I9*9;.CI5<'$
;u>9*+EeqI=9;CI5P@'H$CI5
G^-cU>q+;CI59?#^f$,$CI5-
cU*s+5;??Y;#5H$
CI5G^-cU>qC-9s]9?f$9e,$
CI5-cU’*IH--CI5-cUH*#5+
CI5$9;CI5Eu=#+E539;C“
;P@'H#'"5"=C'sE-CI5
G^-cUs=#5CI5E>-CI5-
cU=CI5EIs#5G\,
=CI5G^-cUHU#5CI5BOOJkLJ995H;
.$'=CI5WC5KCI5G]:]0;
"5"9;$[NAH^\@sc8<+
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1.2.Một số thuật ngữ sử dụng trong hệ mật mã
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T]$$79;WG5e$H#Cj:A9;$
B:A9;$\M9;WT9;CMp5G$“_$
#@;\,5$
b$#@sW\GhWUj
C
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b$#@\sW\GhWUB
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1.3.Định nghĩa mật mã học
2-s?G\D59;*#5C\a99*#+C
CW5",/0:*9;N9J;’GA,5-E?
:œ,5#ACW$sW#$<fT;<I9;+"
8<*d+*<]!W;N9J$-/’G
:G\#ŒAI9;G\'5H.9$Gh,-dG^C@;9$;I^$
#p=<SN9J,}I5G\#ŒGh+CI5sc3#;/
G\C'_$\#Cœ,5#IG\$#+s#C,CW
c3$D5G\#ŒH’G:"G'CI5AI\
;$sG\#Œ
!5,}W\@UI5+$Gh=C
,5$
+9;+G+;Ee:P,C,K,E,DAq5]^,5$

K2f$;<
sCt=+•;CWG3œ,5#JŒdI+
C##"sEtc55$5$I\,/N9J$-/+W
G’G#+CCW;5cJWG;<9;+$•
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1.4.Phân loại hệ mật mã học
R3,/D5]9;93,/D5E?EE
kE?EEI5Gp;^<5$;<5#f\D5
c$^E?EEI5M]@<s
E85;;*
1.4.1.Mật mã cổ điển (cái này ngày nay vẫn hay dùng trong trò chơi tìm mật
thư).
Dựa vào kiểu của phép biến đối trong hệ mật mã cổ điển, người ta
chia hệ mật mã làm 2 nhóm: mã thay thế (substitution cipher) và mã
hoán vị (permutation/ transposition cipher).

Y'$#E?EE5<'HC]#795Jcs5<
';;GhC]#MEJ#JcH@#E?EE
3HC]#795Jcs.$<Hpus,‹Ec'E9*3#]
*#5MEJ#Jc!U9;C]#795Jc;;CWG35<
GhC]C
M0E?EE39; E?EEI5#IC]
#aG\G5e$u5<3#]5$>G\8C]CWf
G3G'
P]0?\^I5G\#ŒGh\sUCS
D5I\,/G\#ŒD5G*I+;YCS’*,}3#]CSU
;CSYHCS ;CSYkHr7U*E?+pH3CWE\
;G+G\#Œ;5,#5*+;R;EFE3
Jm*TIR,}9;CI5D5G*¡dCRI#3$<
-: H1H&rAd#3?-:K HK1HK&rD5YA
P;C\C~Pk(P#MW$<H"54#5n'G3
I5o2I9;+-@#0G@[2I5H"5_$^Ga
^<:qH;^<=#]A_$5-@#0;<;'
$eI59^<Jf$D5-5$CŠGa^<Cq-
@+$,}sJ^$$,\@E\$-Ga^<9-
=IGC][’C][]9;CI5#;<
1.4.2.Mật mã hiện đại
5<J##<E#5E<I5-cUHU9;\5_$#@I5;
\f$=+@5CI52\G\]5;H@5CI5;<E\
s.G]P@'$9*;<>IC9;secret key
cryptography (hay private key cryptography), U9;$I5=@5
CI5#:5<G]AM$9*;<9St0]I5.
9$D585<U?9†G+9+*'CWIE\
s5,†+GU5
\,/'$N9Ju/WEI5’G;CWfG
#f$,/0H’G,}•$N9J$-I@P@'G‹G$+

;s9*P<
I+345#+?-cU9;n-cU9;I#
ICI5=\T
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I“;]smCI5=I5T
J
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E\\$fC=$_$#@;\5$
IHG/,}G\#Œ:795JcAGh,/0CG];<;/
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,},/0]CG];5G\$\;9^<9*
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W_$5,/0E?EE-cUH@;Ee_$5
#^eE\s.G]]9;CP#5H\$f
$s,/0#I';+WC5H
G\$fC#;\E\';G]
Mp5I^<#h$-cU,}#^I9sCs
E0#?_$55<U?9†Y'$eE\#5W
+GUG5@\G\]G]D5CE\sd9
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k ’9CEJ#,:$C-¦#ImC-.9$#aG\
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•C-9;G9C,”JH"s]Gh?3GP]0$
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