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CS 161 Discussion 4

Cryptography II

Shomil Jain

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Asymmetric Cryptography

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aka Public-Key Cryptography

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Diffie Hellman Key Exchange

a public-key encryption scheme

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Discussion Problem #1

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El Gamal Encryption

another public-key encryption scheme!

it’s like one half of diffie hellman

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Discussion Problem #2

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Hashing

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Q: Why did the breach contain only *weak* passwords? Why weren’t any lengthy/complex passwords revealed?

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Q: How could Chegg have avoided this data breach?

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Q: Why is the statement “hashing algorithms can be broken” misleading?

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On the right is the most common passwords from the data breach.

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Most likely: Chegg didn’t hash passwords with a salt!

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(The leaked passwords didn’t include any *strong* passwords, indicating that these came from a pre-computed lookup table).