the basics of cryptography

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?