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INTRODUCTION TO CRYPTOGRAPHY

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A quick introduction on the concepts around cryptography and their main usage

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INTRODUCTION TO CRYPTOGRAPHY

  1. 1. CYBER SECURITY INTRODUCTION TO CRYPTOGRAPHY VERSION: 1.3 DATE: 25/09/2019 AUTHOR: SYLVAIN MARTINEZ REFERENCE: ES-CSIC CLASSIFICATION: PUBLIC
  2. 2. 2 • Presentation goal; • Definition; • History; • Main types; • Logical Operations; • Concept; • Main Algorithms; • Concept; • Type of algorithms; • ECB; • CBC; • Stream Cipher concept; • Keystream; • Main Algorithms; • Overall Concept; • Main Algorithms; CONTENTS PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT • Take Away;
  3. 3. PRESENTATION GOAL 3 LEARN ABOUT ITS MAIN USAGE 3 LEARN ITS MAIN ALGORITHMS 2 LEARN ABOUT CRYPTOGRAPHY CORE CONCEPTS 1 TO LEARN ABOUT CRYPTOGRAPHY CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT Icons: from The Noun Project unless stated otherwisePUBLIC
  4. 4. DEFINITION 4PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT CRYPTOGRAPHY is the science related to hiding information. With the aim to provide a combination or all of the following: Confidentiality, Integrity, Authentication and Non-repudiation. This can be achieved through the design of cipher algorithms.
  5. 5. HISTORY 5PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT KRYPTOS (Greek) meaning HIDDEN, SECRET 1900 BC NON STANDARD HIEROGLYPHS 1500 BC MESOPOTAMIA CLAY TABLETS 700 BC SCYTALE SPARTAN KAMA SUTRA 300 BC 50 BC CAESAR SHIFT CIPHER VIGENÈRE CIPHER 1553 1586 STEGANOGRAPHY QUEENS OF SCOTS 1940 WWII - ENIGMA QUANTUM COMPUTER 2000s
  6. 6. MAIN TYPES 6PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT HIDE DATAENCRYPTION REVEAL ORIGINAL DATADECRYPTION CREATES A UNIQUE SIGNATURE FROM DATAHASH HIDE DATA WITHIN OTHER DATASTEGANOGRAPHY
  7. 7. LOGICAL OPERATIONS 7PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT 1 1 OR = 1 0 0 OR = 0 1 0 OR = 1 1 1 AND = 1 0 0 AND = 0 1 0 AND = 0 1 1 XOR = 0 0 0 XOR = 0 1 0 XOR = 1 OR AND XOR NOR NAND XNORMORE LOGICAL OPERATIONS: NOT
  8. 8. CONCEPT 8PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT To be, or not to be: That is the question INPUT HASH FUNCTION 4565 DEFG 2C4G FG67 DIGEST COMPLETELY DIFFERENT HASH DIFFERENT HASH CANNOT REVERT HASH SAME HASH AVALANCHE EFFECT UNIQUE ONE WAY FAST DETERMINISTIC SMALL SOURCE CHANGE DIFFERENT SOURCE "CLEAR TEXT" SOURCE SAME SOURCE IDEAL HASH FUNCTION
  9. 9. MAIN ALGORITHMS 9PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT ALGORITHM ORIGIN SPECIFICITY MAIN USAGE MD5 RONALD RIVEST 1991 128-BIT HASH VALUE 4 ROUNDS OF 16 OPERATIONS (XOR, AND, OR, NOT) DATA INTEGRITY & CHECKSUM SSL DIGITAL CERT PASSWORDS COLLISION ATTACK NO LONGER SUITABLE STILL WIDELY IN USE SHA-1 NSA 1995 160-BIT HASH VALUE HEXADECIMAL 40 DIGITS LONG 80 ROUNDS CHECKSUM, PWD, SSL/TLS CERT (NOT NOW) U.S GOV APPROVED COLLISION ATTACK SHATTERED CHOSEN-PREFIX NO EASY/CHEAP ATTACKS SHA-2 NSA 2001 224, 256, 384, 512-BIT HASH VALUE 64 OR 80 ROUNDS CHECKSUM, PWD, BITCOIN, TLS, SSL, PGP, SSH, S/MIME, DKIM, DNSSEC, IPSEC PARTIAL COLLISION ATTACK ONLY SHA-3 NSA 2015 KECCACK FAMILY SPONGE CONSTRUCTION ABSORBED/SQUEEZED PADDING, PERMUTATION CHECKSUM, PWD, ETHEREUM, TLS, SSL, DNSSEC, IPSEC NONE KNOWN YET RISKS
  10. 10. OVERALL CONCEPT 10PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT PASSWORD/ KEY ENCRYPTION DECRYPTION To be, or not to be: That is the question PLAIN TEXT fDrTrg1er 65Hjt2s,R. Lks.,3!dAc dvijn4sv CIPHER TEXT
  11. 11. INPUT IS BROKEN INTO BLOCK OF DATA EACH BLOCK OF DATA IS ENCRYPTED/DECRYPTED INPUT IS BROKEN INTO A STREAM OF DATA EACH BITS OF DATA IS ENCRYPTED/DECRYPTED TYPE OF CIPHER ALGORITHMS 11PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT BLOCK CIPHER STREAM CIPHER
  12. 12. BLOCK CIPHER CONCEPT - ECB 12PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT Source: https://elysiumsecurity.com/crypto/page_crypto.html ELECTRONIC CODEBOOK MODE (ECB)
  13. 13. BLOCK CIPHER CONCEPT - CBC 13PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT Source: https://elysiumsecurity.com/crypto/page_crypto.html CHAIN BLOCK CHAINING MODE (CBC)
  14. 14. STREAM CIPHER CONCEPT 14PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT To be, or not to be: That is the question PLAIN TEXT fDrTrg1er 65Hjt2s,R. Lks.,3!dAc dvijn4sv CIPHER TEXT …010010010101… …001011011100… …110100010110… PASSWORD/ KEY XOR KEYSTREAM GENERATOR
  15. 15. LINEAR FEEDBACK SHIFT REGISTER (LFSR) STREAM CIPHER CONCEPT – KEYSTREAM LFSR 15PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT
  16. 16. MAIN ALGORITHMS 16PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT ALGORITHM ORIGIN SPECIFICITY MAIN USAGE RC4 RONALD RIVEST 1987 40-2018 BITS 1 ROUND PERMUTATION "S" KEY-SCHEDULING IV WEP, WPA, BITTORRENT, MS REMOTE DESKTOP, KERBEROS, SKYPE, SSH MULTI SESSION ATTACK ROYAL HOLLOWAY NO LONGER IN TLS [DES] TRIPLE DES IBM [1975], 1998 KEY: 168, 112, [56] BITS BLOCK: 64 BITS [16], 48-DES ROUNDS STANDARD USED GLOBALLY (CREDIT CARD, PGP, ETC). [S-BOX RESISTANT 20 YEARS EARLY] NO LONGER SECURED TWOFISH BRUCE SCHNEIER 1998 KEY: 128, 192, 256 BITS BLOCK: 128 BITS 16 ROUNDS AES FINALIST OPENPGP DIFFERENTIAL ATTACK AES (RIJNDAEL) VINCENT RIJMEN JOAN DAEMEN 1998 KEY: 128, 192, 256 BITS BLOCK: 128 BITS 10, 12 or 14 ROUNDS NEW STANDARD DES/TDES REPLACEMENT SINCE 2002 XSL ATTACK RELATED KEY ATTACK NO PRACTICAL ATTACKS RISKS
  17. 17. OVERALL CONCEPT – RECEIVING DATA 17PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT PUBLIC KEY ENCRYPTION DECRYPTION To be, or not to be: That is the question PLAIN TEXT fDrTrg1er 65Hjt2s,R. Lks.,3!dAc dvijn4sv CIPHER TEXT PRIVATE KEY
  18. 18. OVERALL CONCEPT - AUTHENTICATION 18PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT PUBLIC KEY ENCRYPTION DECRYPTION To be, or not to be: That is the question PLAIN TEXT fDrTrg1er 65Hjt2s,R. Lks.,3!dAc dvijn4sv CIPHER TEXT PRIVATE KEY
  19. 19. MAIN ALGORITHMS 19PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT ALGORITHM ORIGIN SPECIFICITY MAIN USAGE RSA RIVEST SHAMIR ADLEMAN 1977 FACTORISATION KEY: 1,024 – 4,096 BITS 1 ROUND TLS, SSH, ETC. FACTORING PROBLEM NO LONGER A PROBLEM ECDSA NIST 2005 ELLIPTIC CURVE 𝑦" = 𝑥% + 𝑎𝑥 + 𝑏 SIGNATURE, KEY AGREEMENT, PRG SONY/FAILOVERFLOW JAVA FLAWS DSA NIST 1991 ELLIPTIC CURVE KEY GENERATION KEY DISTRIBUTION SIGNING SIGNATURE VERIF SECRECY AND RANDOMNESS OF K DIFFE-HELMAN WHITFIELD DIFFIE MARTIN HELLMAN 1976 MULTIPLICATIVE GROUP OF INTEGERS MODULO P KEY AGREEMENT PROTOCOL MAN IN THE MIDDLE LOGJAM ATTACK RISKS
  20. 20. TAKE AWAY 20PUBLIC CONCLUSIONASYMMETRICSYMMETRICHASHESCONTEXT ONLY USE STANDARD ALGORITHMS1 BEWARE OF THE IMPLEMENTATION2 KEEP YOUR PRIVATE KEYS SAFE3 BEWARE OF EXTERNAL FACTORS4 CHECK FIPS CERTIFICATION DETAILS5
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