Slides do Módulo de Criptografia - Si.lopesgazzani.com.br
Slides do Módulo de Criptografia - Si.lopesgazzani.com.br
Slides do Módulo de Criptografia - Si.lopesgazzani.com.br
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Cifra Cifra One One-Time One Time Time Pad<<strong>br</strong> />
Pad<<strong>br</strong> />
K: CONSTITUICAO (chave)<<strong>br</strong> />
P: ANOITEELONGA (texto claro)<<strong>br</strong> />
C: STX SOH SOH SUB NUL FF VT EM ACK CR ACK SO (texto cifra<strong>do</strong>)<<strong>br</strong> />
45<<strong>br</strong> />
C = P ⊕ K<<strong>br</strong> />
A N O I T E E L O N G A<<strong>br</strong> />
P 0100 0001 0100 1110 0100 1111 0100 1001 0101 0100 0100 0101 10010101 0100 1100 0100 1111 0100 1110 0100 0111 0100 0001<<strong>br</strong> />
C O N S T I T U I C A O<<strong>br</strong> />
K 0100 0011 0100 1111 0100 1110 0101 0011 0101 0100 0100 1001 0101 0100 0101 0101 0100 1001 0100 0011 0100 0001 0100 1111<<strong>br</strong> />
STX SOH SOH SUB NUL FF VT EM ACK CR ACK SO<<strong>br</strong> />
C 00000010 00000001 00000001 00011010 00000000 00001100 00010001 00011001 00000110 00001101 00000110 00001110<<strong>br</strong> />
Técnicas Técnicas <strong>de</strong> <strong>de</strong> Transposição<<strong>br</strong> />
Transposição<<strong>br</strong> />
Obtida pela permutação <strong>do</strong>s símbolos ou letras <strong>do</strong> texto<<strong>br</strong> />
original que reaparecem em posições diferentes no texto<<strong>br</strong> />
cifra<strong>do</strong><<strong>br</strong> />
Cifragem guiada por trilhos ( rail fence technique )<<strong>br</strong> />
O texto original é escrito numa seqüência <strong>de</strong> colunas e <strong>de</strong>pois é<<strong>br</strong> />
obti<strong>do</strong> cifra<strong>do</strong> len<strong>do</strong>-se uma seqüência <strong>de</strong> linhas<<strong>br</strong> />
Ex: Texto original : “ meet me after the toga party”<<strong>br</strong> />
Guiada por trilhos em 2 e 4 linhas:<<strong>br</strong> />
m m t h g r<<strong>br</strong> />
47<<strong>br</strong> />
m e m a t r h t g p r y<<strong>br</strong> />
e t e f e t e o a a t<<strong>br</strong> />
Texto cifra<strong>do</strong> : MEMATRHTGPRYETEFETEOAAT<<strong>br</strong> />
Texto cifra<strong>do</strong> : MMTHGREEEEATEARTPYTFTOA<<strong>br</strong> />
e e e e a t<<strong>br</strong> />
e a r t p y<<strong>br</strong> />
t f t o a<<strong>br</strong> />
Cifra Cifra One One-Time One Time Time Pad<<strong>br</strong> />
Pad<<strong>br</strong> />
• K: ACK GS SOH CAN US (chave)<<strong>br</strong> />
• P: CLONE (texto claro)<<strong>br</strong> />
• C: EQNVZ (texto cifra<strong>do</strong>)<<strong>br</strong> />
• K: ACK RS NUL STX ESC (chave)<<strong>br</strong> />
• P: CONTA (texto claro)<<strong>br</strong> />
• C: EQNVZ (texto cifra<strong>do</strong>)<<strong>br</strong> />
46<<strong>br</strong> />
Técnicas Técnicas Técnicas Técnicas Técnicas <strong>de</strong> <strong>de</strong> Transposição<<strong>br</strong> />
Transposição<<strong>br</strong> />
48<<strong>br</strong> />
C L O N E<<strong>br</strong> />
P 01000011 01001100 01001111 01001110 01000101<<strong>br</strong> />
ACK GS SOH CAN US<<strong>br</strong> />
K 00000110 00011101 00000001 00011000 00011111<<strong>br</strong> />
E Q N V Z<<strong>br</strong> />
C 01000101 01010001 01001110 01010110 01011010<<strong>br</strong> />
C O N T A<<strong>br</strong> />
P 01000011 01001111 01001110 01010100 01000001<<strong>br</strong> />
ACK RS NUL STX ESC<<strong>br</strong> />
K 00000110 00011110 00000000 00000010 00011011<<strong>br</strong> />
E Q N V Z<<strong>br</strong> />
C 01000101 01010001 01001110 01010110 01011010<<strong>br</strong> />
Cifragem usan<strong>do</strong> retângulos<<strong>br</strong> />
O texto original é escrito num retângulo(por ex:4lsx7col), linha<<strong>br</strong> />
a linha, e <strong>de</strong>pois é obti<strong>do</strong> cifra<strong>do</strong> len<strong>do</strong>-se, coluna a coluna,<<strong>br</strong> />
ten<strong>do</strong>-se o cuida<strong>do</strong> <strong>de</strong> permutar a or<strong>de</strong>m das colunas<<strong>br</strong> />
Ex: Texto original : “ attack postponed until two am xyz”<<strong>br</strong> />
No retângulo:<<strong>br</strong> />
a t t a c k p<<strong>br</strong> />
o s t p o n e<<strong>br</strong> />
d u n t i l t<<strong>br</strong> />
w o a m x y z<<strong>br</strong> />
3 4 1 2 5 6 7<<strong>br</strong> />
Chave <strong>de</strong>finin<strong>do</strong> a or<strong>de</strong>m das<<strong>br</strong> />
colunas no texto cifra<strong>do</strong><<strong>br</strong> />
Texto cifra<strong>do</strong> : TTNAAPTMTSUOAODWCOIXKNLYPETZ<<strong>br</strong> />
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