The Basics of Cryptography
Post on 01-Jul-2015
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CRYPTOGRAPHYTHE BASICS
by JAMES HALL
DIRECTOR/FOUNDER AT
jsPDF JAVASCRIPT PDF GENERATION LIBRARY
WHAT ISCRYPTOGRAPHY?
DEMO
A CIPHERIS A DIGITAL
LOCK
CAESAR CIPHERUSED IN WARSAROUND 50BC
ABCDEFGHIJKLM
XYZABCDEFGHIJ
ABCDEFGHIJKLM
XYZABCDEFGHIJ
Shift Cipher
I LOVE FREE BROWNIES
I LOVE FREE BROWNIES
Input
Output
0Shift Value (Key)
Shift Cipher
I LOVE FREE BROWNIES
J MPWF GSFF CSPXOJFT
Input
Output
1Shift Value (Key)
Shift Cipher
I LOVE FREE BROWNIES
K NQXG HTGG DTQYPKGU
Input
Output
Shift Value (Key)
2
One-Time Pad
ILOVEFREEBROWNIES
KLREJNUNGBSXZVNNU
Input
Output
Key
20395839201938592
STREAM CIPHER
ILOVEFREEBROWNIESInput
Output
78943Key (Shared secret)
Key stream (PRNG)
06947294068240593
IQXZLHAIEHZQANNNV
HOW TO GET ASHAREDSECRET
(WITH THIS ONE WEIRD TRICK)
TOM HARRY
EVE
TOM HARRY
EVE
TOM HARRY
EVE
TOM HARRY
EVE
TOM HARRY
EVE
TOM HARRY
EVE
TOM HARRY
EVE
A LOCK ICONDOESN’T MEANYOU’RE SECURE
FORGED GOOGLE.COM CERTS
USED TO SPYon 300,000 Iranian users
SSLIS BROKEN
Stanford JavaScriptCrypto Library
ANY QUESTIONS?
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