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The Data Encryption Standard (DES)
The same module told visually, ready to present. Speaker notes carry the full explanation.
Symmetric
The Data Encryption Standard
The first cipher the world standardized. It was retired by a key that was always too short, not by a flaw
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The core structure
A Feistel round
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Design trade-off
Feistel versus SPN
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The numbers
DES by the numbers
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January 1999
56 bits fell to brute force
The design held up; the key size didn't
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Advanced · meet in the middle
Why double DES isn't 112 bits
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The fix
Triple DES: encrypt, decrypt, encrypt
The third pass closes the meet-in-the-middle gap, at three times the cost
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Legacy
What AES kept, and what it dropped
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