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Class 9

Class 9. Questions about term paper—list of possible topics available on line—proposal due 9/27 Communications assignment—discuss Finish communications discussion. Intercepting Communications (cont’d). Outline. Overview of the Controversies Intercepting Communications

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Class 9

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  1. Class 9 • Questions about term paper—list of possible topics available on line—proposal due 9/27 • Communications assignment—discuss • Finish communications discussion Mary Jean Harrold

  2. Intercepting Communications (cont’d) Mary Jean Harrold

  3. Outline • Overview of the Controversies • Intercepting Communications • Cryptography and Its Uses • Encryption Policy: Access to Software, Keys, and Plaintext • Fundamental Issues Mary Jean Harrold

  4. Cryptography and Its Uses (1) • Cryptography • Definition: • Hiding data in plain sight. • Terms: • Plaintext: Original, readable message or data. • Cyphertext: Modified, unreadable message or data. • Encryption: The act of converting plaintext into cyphertext. • Decryption: The act of reverting cyphertext back to readable, plaintext. Q1:Are there other ways to hide a message in plain sight? Mary Jean Harrold

  5. Cryptography and Its Uses (2) • Public Key Cryptography • How it works: • User creates a mathematically-related key pair (public and private keys). • Public keys are shared publicly; private keys are kept secret. • Public keys are used to encrypt message or data. • Private keys are used to decrypt message or data. • Benefits: • No secret keys need be shared or transmitted. • Very secure. Q2: How does key-size affect the ‘strength’ of encryption? Mary Jean Harrold

  6. Cryptography and Its Uses (3) • Encryption • Used by: • Military personnel. • Financial institutions. • Human-rights activists. • Government agencies. • Anyone wanting to keep messages or data private. Q3: Why are strong encryption tools needed by human-rights activists? Mary Jean Harrold

  7. Cryptography and Its Uses (4) • Steganography • Definition: • Hiding data so that its existence is not known. • Examples: • Digital watermarks. • Hiding text in image files. • Used by: • Military, • Publishers, • Anyone wishing to hide messages or data. Q4: How might steganography be incorporated into textbooks? Why? Mary Jean Harrold

  8. Encryption Policy: Access to Software, Keys, and Plaintext • Secrecy and Export Controls • Control of Secrecy • The NSA designs unbreakable codes for the U.S. government. • The NSA attempts to break codes used by other governments. • In the past, the NSA also controlled the funding for and publishing of cryptographic research. • Control of Exportation • Early U.S. policy prevented the exportation of strong encryption. • Meanwhile, foreign production and use of strong encryption negatively impacted U.S. competition in the world market. • Cryptographic researchers, privacy advocates, and others successfully challenged exportation restrictions. Q5: Why did the U.S. government insist on controlling export of strong crypto? Mary Jean Harrold

  9. Fundamental Issues (1) • Role of Secrecy • U.S. Policy Keeps Secret: • Cryptographic research. • Wiretap ease or difficulty. • Encryption algorithms. • Software (e.g. Carnivore). • Global endeavors (e.g. Echelon). • Problems: • Secret algorithms cannot be tested by experts. • ‘Backdoors’ might exist. • NSA-influenced wiretap and encryption exportation bills Mary Jean Harrold

  10. Fundamental Issues (2) • The Ever-changing Status Quo • Past: • Simple codes and cyphers. • Present: • 512-bit RSA encryption. • AES (Advanced Encryption Standard). • Future: • Quantum computing. • Quantum cryptography. Q7:Today, do coders or decoders have the upper hand? Mary Jean Harrold

  11. Fundamental Issues (3) • Trust in Government • Appropriate or Abusive? • Wiretapping by FBI and local police. • Wiretapping by NSA. • Strong encryption restrictions. • Roving wiretaps. • Cell-phone tracking (and E-911). • Development of a nationwide standard for surveillance. • Immediate decryption technology built in to the Internet. Mary Jean Harrold

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