Spring 2018 Dr. Rosenbaum FUNDAMENTALS OF IT Lecture 10: Encryption, Hacking, Digital Forensics
This Week Cryptography Cryptography Terminology Symmetric Key Encryption Asymmetric Key Encryption Distinguishing between Hashing & Encryption
This Week Hacking History of Hacking What is Hacking? Who is Hacker? Famous hackers in history Why do Hackers hack? Types of Hacking How to give a password to account What should do after hacked How to secure our data Advantages of Hacking Disadvantages of Hacking Conclusion
This Week Digital Forensics
Definitions Cryptography comes from the Greek work for secret writing Traditionally , cryptography refers to: The practice and the study of encryption Transforming information in order to prevent unauthorized people to read it. Today , cryptography goes beyond encryption/decryption to include Techniques for making sure that encrypted messages are not modified en-route Techniques for secure identification/authentication of communication partners.
Definitions Encryption : Transform representation so it is no longer understandable Decryption : Reversing encryption process Cryptosystem : A combination of encryption and decryption methods Cleartext or Plaintext : Information before encryption Cipher : An algorithm used to encrypt and decrypt text Cipher text : Information in encrypted form One-way cipher : Encryption system that cannot be easily reversed (used for passwords)
The Why of Cryptography Confidentiality : protection against eavesdropping Authentication : assurance parties involved in a communication are who they claim to be Message Integrity : assurance that messages are not altered en route Availability : making sure that communication systems are not shut down by intruders.
Classifications Cryptography Symmetric key cryptography Asymmetric key cryptography (Public key cryptography) Classical cryptography Transposition Cipher Substitution Cipher Modern Cryptography Stream Cipher Block Cipher
Substitution Ciphers A cipher that substitutes one character with another. These can be as simple as swapping a list, or can be based on more complex rules. These are NOT secure anymore, but they used to be quite common.
Caesar ciphers A B C D E F G H I J K L M N O P Q R S T U V W X Y Z D E F G H I J K L M N O P Q R S T U V W X Y Z A B C Substitute the letters in the second row for the letters in the top row to encrypt a message Encrypt(COMPUTER) gives FRPSXWHU Substitute the letters in the first row for the letters in the second row to decrypt a message Decrypt(Encrypt(COMPUTER)) = Decrypt(FRPSXWHU) = COMPUTER
Cryptanalysis The process of decrypting a message without knowing the cipher or the key used to encrypt it Substitution and transposition ciphers are easy for modern computers to break To protect information more sophisticated schemes are needed
Encryption on computers
- Spring '10
- Cryptography, Public-key cryptography, Pretty Good Privacy, GNU Privacy Guard, asymmetric key encryption