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Cryptography and PKI

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- Cryptography and Security
- Methods of Encryption and Decryption
- What is an Algorithm?
- Symmetric Algorithm
- Asymmetric Algorithm
- Hybrid Encryption
- Hashing Algorithm
- Securing the Algorithm or the Key
- Hash Value and Rainbow Table
- Digital Signature
- PKI

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Cryptography and PKI

  1. 1. Introduction to Cryptography and PKI Presented By: Rabei Hassan
  2. 2. • Rabei Hassan • CISSP-ISSAP, CCSP, CRISC, CISM, CISA, CEH, ECSA, CHFI, Security+ • MCTS, MCSE: Security, MCDBA, MCSA: Messaging • More than 18 years working experience at various IT fields • Infrastructure and Info Security Consultation and Training • IT Management • Web and Windows Application Development • Systems and Database Administration • https://au.linkedin.com/in/rabei-hassan-564b3214
  3. 3. Session Objectives • Cryptography and Security • Methods of Encryption and Decryption • What is an Algorithm? • Symmetric Algorithm • Asymmetric Algorithm • Hybrid Encryption • Hashing Algorithm • Securing the Algorithm or the Key • Hash Value and Rainbow Table • Digital Signature • PKI
  4. 4. Cryptography and Security Confidentiality Integrity Authenticity Non-Repudiation
  5. 5. Methods of Encryption and Decryption • Symmetric • Use ONLY One Key for encryption and decryption • Asymmetric • Use Two Keys, • One key will be used for encryption • The other key will be used for decryption. • Hashing • One-Way encryption ..!
  6. 6. What is an Algorithm ? • Instructions; the steps that we need to follow to do the operation. • In general, it will has two types of instructions: • Instructions for how to do the encryption • Instruction for how to do the decryption Symmetric Algorithms Encryption Instructions using Key X Step 1 - …….. Step 2 - …….. Step 3 - …….. Step 4 - …….. Decryption Instructions using Key X Step 1 - …….. Step 2 - …….. Step 3 - …….. Step 4 - …….. Asymmetric Algorithms Encryption Instructions using Key X Step 1 - …….. Step 2 - …….. Step 3 - …….. Step 4 - …….. Decryption Instructions Using Key Y Step 1 - …….. Step 2 - …….. Step 3 - …….. Step 4 - …….. Hashing Algorithms Instructions for One-Way Encryption No-KEY Step 1 - …….. Step 2 - …….. Step 3 - …….. Step 4 - …….. Plain Text Cipher Text Plain Text Hash Value
  7. 7. Symmetric Algorithms (1/3) • Vigenere Cipher • Plain Text : Welcome To Cryptography • Key: RAMGuide Encryption Instructions 1. Put the plain text in a raw. 2. Put the Key in a second line raw below the plain text raw. 3. If the key-size is smaller than the plain text size, then repeat it until it become the same size as the plain text. 4. According to the table on the right section, the cipher text will be the inter section between the character in the plain text raw and the character in the key raw. Plain Text W E L C O M E T O C R Y P T O G R A P H Y Key R A M G U I D E R A M G U I D E R A M G U Cipher Text N E X I . . . . . . . . . . . . . . . . . Decryption Instructions
  8. 8. Binary Mathematics X AND Y X OR Y X XOR Y Both values need to be true, so the output will be true. One OR Two values need to be true so the final value will be true. One and Only One value need to be true so the final value will be true.
  9. 9. Symmetric Algorithms (2/3) • Vernam (One-Time Pad) Cipher • Plain Text : Welcome • Key: RAMGuid Encryption Instructions 1. The key must be the same size as the plain text. 2. Put the Key in a second line raw below the plain text raw. 3. XOR between them on the bit level. Plain Text W 0101 0111 E 0100 0101 L 0100 1100 C 0100 0011 O 0100 1111 M 0100 1101 E 0100 0101 Key R 0101 0010 A 0100 0001 M 0100 1101 G 0100 0111 U 0101 0101 I 0100 1001 D 0100 0100 Cipher Text 0000 0101 0000 0100 . . . . . W 0 1 0 1 0 1 1 1 R 0 1 0 1 0 0 1 0 0 0 0 0 0 1 0 1 E 0 1 0 0 0 1 0 1 A 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 Decryption Instructions
  10. 10. Symmetric Algorithms (3/3) • DES …………………. [Key Size is …. 56-bit] • 3DES ……………….. [Key Size could be …… 112-bit …… 168-bit] • AES …………………. [Key Size could be ……. 128-bit ..… 192-bit …. 256-bit]
  11. 11. Asymmetric Algorithms • Will use two keys: • Public Key ……………………. [Any one can get a copy of it] • Private Key ………………….. [Maintained by the owner] • Public/Private key is for one entity/individual only. Amr Jana 1. Amr will send his Public Key to Jana 2. Jana will encrypt the message with Amr Public Key3. Jana will send the secret message to Amr 4. Amr will decrypt the secret message with his own Private Key Amr Public Key Amr Private Key Jana Private Key Amr need to receive something securely from Jana Amr Public Key
  12. 12. Asymmetric Algorithms • Diffie-Hellman ………..[Key Exchange] • EL Gamal …………………[Key Exchange – Encryption – Digital Signature] • RSA ………………………….[Key Exchange – Encryption – Digital Signature] • Elliptic Curve ………….. [Key Exchange – Encryption – Digital Signature]
  13. 13. Symmetric vs. Asymmetric Algorithms Symmetric Asymmetric Key Distribution X  Performance Fast Slow 1000 ~ 10,000 slower than Symmetric Scalability X A B C D E F 5 Keys 4 Keys 3 Keys 2 Keys 1 Key Total number of Keys = 5 + 4 + 3 + 2 + 1 = 15 6 Entities (Individuals) Symmetric 6 Entities (Individual) – each one will has two keys (Public/Private) 6 X 2 = 12 Asymmetric
  14. 14. Hybrid Encryption (Symmetric + Asymmetric) HTTPS://www.Amazon.com You want to Transfer your Credit-Card information securely Amazon Public Key Amazon Private Key Amazon will send its Public Key A session Symmetric Key will be generated locally on your own machine Credit Card Information The Encrypted Credit-Card Information will be transferred to Amazon.com Symmetric Key The Session Symmetric Key will be transferred one time only during the whole session
  15. 15. Hash Algorithm (1/2) • One-way encryption, that will generate a fixed length value. ABC Funny Hashing Algorithm  1. Get the ASCII Code of each character 2. Multiply by the position 3. Get the Sum 1. A(65) B(66) C(67) 2. 65 X 1 66X2 67X3 3. 65 + 132 + 201 398  Securing PasswordsIntegrity [File Transfer]
  16. 16. Hash Algorithm (2/2) • SHA1 ………………………… [160-bit] • SHA2 ………………………… [256-bit / 512-bit] • MD5 …………………………. [128-bit]
  17. 17. Securing the Algorithm or the Key ? • Pros/Cos of securing the algorithm • Pros/Cos of making the algorithms publicly accessible and securing only the key • The longer the key, the harder to be compromised. Algorithm Instructions Know the exact algorithm Know the exact key   4 Digits Key [0110] 0000 0001 0010 0100 1000 . . . . 2x = 24 = 16 128-bit Key = 2128 = 3.4028236692093846346337460743177e+38  Brute-force Attack Key need to be changed from time to time
  18. 18. Hash Value and Rainbow Table ABC  398Hashing 1. Generate “AAA” 2. Generate the Hash-Value for …… “AAA” 3. Compare the Hash-Value of ….. “AAA” …. with the stolen one “BBB” “BBB” “BBB” Value MD5 SHA1 AAA 3c01… 6f358… BBB a2c9a… bb27f… . . . . . . . . . Demo: Generate and Crack Hash Value Rainbow Table
  19. 19. Digital Signature Amr Jana Jan Public Key Amr Private Key Amr Public Key Jana Private Key Amr want to send something securely to Jana Modification to be detected / To be sure it is from Amr 1. Type a message “ABC” 2. Hash the message and get the hash value 3. Encrypt the hash value using the Amr Private Key ABC Hash Value ABC Hash Value Hash Value Integrity Authenticity Non-Repudiation Amr Public Key   
  20. 20. Public Key Infrastructure – PKI Public/Private Public/Private Public/Private Public/Private X.509 How can we transfer the Public Key / File Format
  21. 21. Public Key Infrastructure – PKI Public/Private Public/Private Public/Private Public/Private Certificate Authority (CA) Who Create/Generate this Certificate Public Key X.509 How can we transfer the Public Key / File Format 1. How can you trust this certificate ... ? 2. Does this site really belong to ... ? Trust A Trust B B Trust C Trust Then A will Trust B 
  22. 22. Public Key Infrastructure – PKI Public/Private Public/Private Public/Private Public/Private Certificate Authority (CA) Who Create/Generate this Certificate How can we transfer the Public Key / File Format 1. How can you trust this certificate ... ? 2. Does this site really belong to ... ? Does this certificate really generated by a Trusted CA ?
  23. 23. Public Key Infrastructure – PKI Public/Private Certificate Authority (CA) Public Key Does this certificate really generated by a Trusted CA ? Hash Value DS Hash Value Public Key Hash Value CA Public Key  Public Trusted CA Local Trusted CA Demo: Where we can find Trusted CAs
  24. 24. Confidentiality Integrity Authenticity Non-Repudiation Public Key Infrastructure – PKI
  25. 25. Hybrid Encryption (Symmetric + Asymmetric) HTTPS://www.Amazon.com You want to Transfer your Credit-Card information securely Amazon Public Key Amazon Private Key Amazon will send its Certificate (which contain its Public Key) A session Symmetric Key will be generated locally on your own machine Credit Card Information The Encrypted Credit-Card Information will be transferred to Amazon.com Symmetric Key The Session Symmetric Key will be transferred one time only during the whole session Authenticity & Confidentiality
  26. 26. Digital Signature Amr Jana Jan Public Key Amr Private Key Amr Public Key Jana Private Key Amr want to send something securely to Jana Modification to be detected / To be sure it is from Amr 1. Type a message “ABC” 2. Hash the message and get the hash value 3. Encrypt the hash value using the Amr Private Key ABC Hash Value ABC Hash Value Hash Value Integrity Authenticity Non-Repudiation Amr Public Key   
  27. 27. Public Key Infrastructure – PKI Certificate Authority (CA) Public Trusted CA Local Trusted CA Number / Location Administration Servers/Computers Users Application/Services Network Devices Certificates & Backup Confidentiality Integrity Authenticity Non-Repudiation Issue Policy and Methods Distribution Policy and Methods
  28. 28. Session Objectives • Cryptography and Security • Methods of Encryption and Decryption • What is an Algorithm? • Symmetric Algorithm • Asymmetric Algorithm • Hybrid Encryption • Hashing Algorithm • Securing the Algorithm or the Key • Hash Value and Rainbow Table • Digital Signature • PKI

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