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Podcast
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Questions and Answers
Questions and Answers
Which of the following is a true statement about modern symmetric block cipher design principles?
Which of the following is a true statement about modern symmetric block cipher design principles?
- Confusion refers to spreading the information and any minor changes in plaintext should lead to a large change in the ciphertext. (correct)
- Confusion and diffusion are achieved by substitutions only.
- Permutations act on smaller groups of bits.
- Diffusion refers to hiding the relation between ciphertext and key.
What is the main reason DES is no longer considered secure?
What is the main reason DES is no longer considered secure?
- Its block length is too short.
- Its key length is too short and advancements in computing power made it vulnerable to exhaustive keysearch. (correct)
- It is too slow for modern encryption needs.
- It uses a weak substitution-permutation network.
What is the block length of AES?
What is the block length of AES?
- 128 bits (correct)
- 256 bits
- 64 bits
- 192 bits
What is the maximum key length for AES?
What is the maximum key length for AES?
What is the purpose of the Mix Columns step in AES encryption?
What is the purpose of the Mix Columns step in AES encryption?
What is the purpose of the Add Round Key step in AES encryption?
What is the purpose of the Add Round Key step in AES encryption?
What is the purpose of the Shift Rows step in AES encryption?
What is the purpose of the Shift Rows step in AES encryption?
What is the purpose of the SubBytes step in AES encryption?
What is the purpose of the SubBytes step in AES encryption?
What is the main difference between DES and Triple DES?
What is the main difference between DES and Triple DES?
What is the purpose of the key expansion algorithm in AES?
What is the purpose of the key expansion algorithm in AES?
What is the main advantage of using a variable key length in symmetric block ciphers?
What is the main advantage of using a variable key length in symmetric block ciphers?
What is the main reason DES is no longer considered secure?
What is the main reason DES is no longer considered secure?
What is the block length of AES?
What is the block length of AES?
What is the purpose of the Mix Columns step in AES encryption?
What is the purpose of the Mix Columns step in AES encryption?
What is the purpose of the Shift Rows step in AES encryption?
What is the purpose of the Shift Rows step in AES encryption?
What is the purpose of the SubBytes step in AES encryption?
What is the purpose of the SubBytes step in AES encryption?
What is the purpose of confusion in modern symmetric block cipher design?
What is the purpose of confusion in modern symmetric block cipher design?
What is the purpose of diffusion in modern symmetric block cipher design?
What is the purpose of diffusion in modern symmetric block cipher design?
What is the combination of substitutions and permutations used for in modern symmetric block cipher design?
What is the combination of substitutions and permutations used for in modern symmetric block cipher design?
What is the key length requirement for Data Encryption Standard (DES)?
What is the key length requirement for Data Encryption Standard (DES)?
What made Data Encryption Standard (DES) vulnerable to exhaustive keysearch?
What made Data Encryption Standard (DES) vulnerable to exhaustive keysearch?
What is the maximum key length requirement for Advanced Encryption Standard (AES)?
What is the maximum key length requirement for Advanced Encryption Standard (AES)?
What is the order of the operations used for ENCRYPTION in Advanced Encryption Standard (AES)?
What is the order of the operations used for ENCRYPTION in Advanced Encryption Standard (AES)?
What is the order of the INVERSE operations used for decryption in Advanced Encryption Standard (AES)?
What is the order of the INVERSE operations used for decryption in Advanced Encryption Standard (AES)?
Questions and Answers
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Flashcards
Flashcards
What is Confusion?
What is Confusion?
Spreading information so minor plaintext changes cause large ciphertext changes.
Why is DES insecure?
Why is DES insecure?
Its key length is too short; computing power enables exhaustive keysearch.
AES Block Length?
AES Block Length?
128 bits
Max AES Key Length?
Max AES Key Length?
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Mix Columns Purpose?
Mix Columns Purpose?
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Add Round Key Purpose?
Add Round Key Purpose?
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Shift Rows Purpose?
Shift Rows Purpose?
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SubBytes Purpose?
SubBytes Purpose?
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DES vs Triple DES?
DES vs Triple DES?
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Key Expansion Purpose?
Key Expansion Purpose?
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Advantage: Variable Key Length?
Advantage: Variable Key Length?
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Purpose of Confusion?
Purpose of Confusion?
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Purpose of Diffusion?
Purpose of Diffusion?
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Substitutions & Permutations?
Substitutions & Permutations?
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DES Key Length?
DES Key Length?
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DES Vulnerability?
DES Vulnerability?
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AES Max Key Length?
AES Max Key Length?
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AES Encryption Order?
AES Encryption Order?
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AES Decryption Order?
AES Decryption Order?
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Flashcards
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Study Notes
Study Notes
Symmetric Block Cipher Design Principles
- In modern symmetric block cipher design, the principles of confusion and diffusion are used to ensure security.
AES (Advanced Encryption Standard)
- The block length of AES is 128 bits.
- The maximum key length for AES is 256 bits.
- The purpose of the Mix Columns step is to provide diffusion by mixing the columns of the state matrix.
- The purpose of the Add Round Key step is to add the round key to the state matrix.
- The purpose of the Shift Rows step is to provide diffusion by shifting the rows of the state matrix.
- The purpose of the SubBytes step is to provide confusion by substituting the bytes of the state matrix.
DES (Data Encryption Standard)
- The main reason DES is no longer considered secure is that its key length (56 bits) is too short and can be broken by exhaustive key search.
- The key length requirement for DES is 56 bits.
- What made DES vulnerable to exhaustive key search is its short key length.
Triple DES
- The main difference between DES and Triple DES is that Triple DES uses three iterations of the DES algorithm with three different keys.
Key Management
- The purpose of the key expansion algorithm in AES is to expand the user-provided key into a series of round keys.
- The main advantage of using a variable key length in symmetric block ciphers is that it provides more flexibility and security.
AES Operations
- The order of the operations used for encryption in AES is: Add Round Key, SubBytes, Shift Rows, Mix Columns.
- The order of the inverse operations used for decryption in AES is the reverse of the encryption operations.
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