PPT-Public Key Cryptography: Encryption, Signatures, FDH

The ROM FDH using the ROM From previous lecture Ciphers Stream ciphers many follow OTP PRG strategy Block ciphers work on plaintext of limited size block output ciphertexts of same size. Sixth Edition. by William Stallings . Chapter 9. Public Key Cryptography and RSA. “Every . Egyptian received two names, which were known respectively as the true name and the good name, or the great name and the little name; and while the good or little name was made public, the true or great name appears to have been carefully concealed. Sixth Edition. by William Stallings . Chapter 10. Other Public-Key Cryptosystems. “Amongst the tribes of Central Australia every man, woman, and child has a secret or sacred name which is bestowed by the older men upon him or her soon after birth, and which is known to none but the fully initiated members of the group. This secret name is never mentioned except upon the most solemn occasions; to utter it in the hearing of men of another group would be a most serious breach of tribal custom. When mentioned at all, the name is spoken only in a whisper, and not until the most elaborate precautions have been taken that it shall be heard by no one but members of the group. The native thinks that a stranger knowing his secret name would have special power to work him ill by means of magic.”. Chapter 9 - . Public-Key Cryptography. Fifth Edition. by William Stallings . Lecture slides by Lawrie Brown. Why Public-Key Cryptography?. developed to address two key issues:. key distribution. – how to have secure communications in general without having to trust a KDC with your key. Slides by Kent Seamons and Tim van . der. Horst. Last Updated: Oct . 7. , 2013. Digital Signatures. Diagram illustrating how to sign a message. Why do we use a one-way hash?. How does a collision or second pre-image attack relate to this?. Algorithms. Scott Chappell. What is Cryptography?. Definition: the art of writing or solving codes. Basic Encryption Methods. Caesar Shift. Simple Substitution Cipher. Fun to use, but are easily cracked by computers and even by humans. Symmetric Encryption. Key exchange . Public-Key Cryptography. Key exchange. Certification . Why Cryptography. General Security Goal. - . Confidentiality . (. fortrolig. ). - . End-point Authentication . CS 161: Computer Security. Prof. . Raluca. Ada . Popa. Sept 13, 2016. Announcements. Project due Sept 20. Special guests. Alice . Bob. The attacker (Eve - “eavesdropper”, Malice). Sometimes Chris too. 1. Administrative Note. Professor Blocki is traveling and will be back on Wednesday. . E-mail: . jblocki@purdue.edu. . Thanks to Professor Spafford for covering the first lecture!. 2. https://www.cs.purdue.edu/homes/jblocki/courses/555_Spring17/index.html. UNIT 4 LESSON 7 – 2 DAY LESSON. VOCABULARY ALERT. :. asymmetric encryption.  - used in public key encryption, it is scheme in which the key to encrypt data is different from the key to decrypt. .. pk. , . sk. pk. c. . . . Enc. pk. (m). m. = . Dec. sk. (c). c. pk. pk. Public-key encryption. A public-key encryption scheme is composed of three PPT algorithms:. Gen: . key-generation algorithm. Steven M. Bellovin. https://www.cs.columbia.edu/~smb. What is Cryptography?. Literally: “hidden writing”. (Technical, the entire field is “cryptology”, but almost no one except the NSA and historians uses that word.). Signature schemes. A . signature scheme . is . defined by . three PPT algorithms . (Gen, . Sign, . Vrfy. ): . Gen: takes as input 1. n. ; outputs . pk. , . sk. Sign: . takes . as input a private key . Crypto is amazing. Can do things that initially seem impossible. Crypto is important. It impacts each of us every day. Crypto is fun!. Deep theory. Attackers’ mindset. Necessary administrative stuff. P. ublic-key encryption ( Asymmetric Encryption). Asymmetric encryption is a form of cryptosystem in which . encryption and . decryption are performed using the different keys—one a public . key and .