Cryptography
- 1. Presented by: Guided by: Laiba Rehman Mrs. Neelam Roll No.-
- 2. INDEX Introduction What is cryptography? Purpose of cryptography Architecture of cryptography Characteristics of cryptography Types of cryptography Process of cryptography Types of cryptography algorithms Attacks of cryptography Conclusion
- 3. Introduction The internet or the global internet is the internationally connected network of computer networks with addresses that are administrated IANA(Internet address and Naming Authority). There are many aspects to security and many applications ,ranging from secure commerce and payments to private communication and protecting passwords. One essential aspect for secure communications is that of cryptography.
- 4. What is cryptography? Cryptography derived its name from a Greek word called “krypto’s” which means “Hidden Secrets”. Cryptography is the practice and study of hiding information. It is the Art and Science of converting a plain intelligible data into an unintelligible data and again retransforming that message into its original form. It provides Confidentiality , Integrity and Accuracy.
- 5. Important terms in cryptography Plaintext: Encryption: Cipher text Decryption key
- 6. Cryptanalysis: Cryptographers: Cryptanalysts: Cryptology
- 7. Caesar Cipher Technique 1. Simple Substitution Technique 2. Working – Encryption 1. Each alphabet in the message is replaced by another alphabet 3 places DOWN the line 3. Working – Decryption 1. Each alphabet in the message is replaced by another alphabet 3 places up the line. A B C D E R Y P T N C D E F G D E C R Y P T
- 8. Purpose Of Cryptography Authentication: The process of proving one’s identity. (The primary forms of host-to-host authentication on the Internet today are name-based or address-based , both of which are notoriously weak.) Privacy/Confidentiality: Ensuing that no one can read the message except the intended receiver.
- 9. Integrity: Assuring the receiver that the received message has not been altered in any way from the original. Non-repudiation: A mechanism to prove that the sender really sent this message.
- 10. Working of encryption and decryption Alice Plain Text ABC Cipher Text DEF Internet Cipher Text DEF Plain Text ABC Bob Tom What is DEF?
- 11. Types of cryptographic algorithms 1. Secret key (symmetric) cryptography : 1. same key used to encrypt and decrypt 2. faster compared to public key encryption 3. key needs to be secured securely 2 Public key (asymmetric) cryptography: 1. uses a public key and private key 2. slower compared with symmetric key
- 12. Crypto Analysis Attacks 1. Cipher text only attack (a) Given: 1. Cipher text of many messages , encrypted with same key 2. C1 = Ek(P1), C2 = Ek(P2),…..Ci = Ek (Pi) (b) Task 1. Find the plain text of these messages or even better the key 2.Find P1, P2, …… Pi or K …. Or Pi+1
- 13. Known plain text attack (a) Given: 1. Cipher text and plain text of the corresponding messages. 2. P1,C1 = Ek(P1), P2,C2 = Ek(P2) , … Pi,Ci = Ek(Pi) (b) Task: 1. Find k 2. Or algorithm to infer Pi+1 from CI+!
- 14. Conclusion Cryptography, being an art of encrypting and decrypting confidential information and private messages, should be implemented in the network security to prevent any leakage and threat.
- 15. THANK YOU.