lecture2

lecture2 - 9/11/03 Lecture 2: Private Key Cryptography CS...

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Lecture 2: Private Key Cryptography CS 392/6813: Computer Security Fall 2010 * Adopted from Previous Lectures by Nasir Memon 9/16/2010 Lecture 2 - Private Key Cryptography 2 Course Administration ± HW#1 due by midnight today ± Solution will be posted soon ± HW#2 will be posted by the weekend ± Would be due in 10 days ± TA Session for Jon Voris: ± Email: jvoris@isis.poly.edu ± 5-6pm Mondays or Tuesdays (subject to room availability) – please wait for further announcement
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9/16/2010 Lecture 2 - Private Key Cryptography 3 Course Administration -- Partners ± Please indicate the name of your partner on your HW1 submission ± In case you are not able to find a partner yourself, please send me an email notifying me about this (if you haven't already done so). Please do this by tomorrow midnight. ± Instructions to submit team homeworks will be provided a bit later 9/16/2010 Lecture 2 - Private Key Cryptography 4 Outline of today’s lecture ± Cryptography Overview ± Private Key Cryptography: Encryption
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9/16/2010 Lecture 2 - Private Key Cryptography 5 Cryptography ± Etymology: Secret (Crypt) Writing (Graphy) ± Study of mathematical techniques to achieve various goals in information security, such as confidentiality, authentication, integrity, non- repudiation, etc. ± Not the only means of providing information security, rather a subset of techniques. ± Quite an old field! 9/16/2010 Lecture 2 - Private Key Cryptography 6 Private Key/Public Key Cryptography ± Private Key : Sender and receiver share a common (private) key ± Encryption and Decryption is done using the private key ± Also called conventional/shared-key/single-key/ symmetric-key cryptography ± Public Key : Every user has a private key and a public key ± Encryption is done using the public key and Decryption using private key ± Also called two-key/asymmetric-key cryptography
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9/16/2010 Lecture 2 - Private Key Cryptography 7 Cryptography: Cast of Characters ± Alice (A) and Bob (B): communicating parties ± Eve (E): Eavesdropping (or passive) adversary ± Mallory (M): Man-in-the-Middle (or active adversary ± Trent (T): a trusted third party (TTP) 9/16/2010 Lecture 2 - Private Key Cryptography 8 Common Terminologies ± Plaintext ± Key ± Encrypt (encipher) ± Ciphertext ± Decrypt (decipher) ± Cipher ± Cryptosystem ± Cryptanalysis (codebreaking) ± Cryptology: Cryptography + Cryptanalysis
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9/16/2010 Lecture 2 - Private Key Cryptography 9 Private key model 9/16/2010 Lecture 2 - Private Key Cryptography 10 Open vs Closed Design ± Closed Design (as was followed in military communication during the World War I/II) ± Keep the cipher secret ± Also sometimes referred to as the “proprietary design” ± Bad practice! (why?) ± Open Design ( Kerckhoffs' principle ) ± Keep everything public, except the key ± Good practice – this is what we focus upon!
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9/16/2010 Lecture 2 - Private Key Cryptography 11 Private Key Encryption: main functions 1.
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This note was uploaded on 11/02/2010 for the course CS 392 taught by Professor Staff during the Spring '08 term at NYU Poly.

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lecture2 - 9/11/03 Lecture 2: Private Key Cryptography CS...

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