CYG Chapter 5 Fast Block Ciphers
Questions about the lecture 'Cryptography' of the RWTH Aachen Chapter 5 Fast Block Ciphers
Questions about the lecture 'Cryptography' of the RWTH Aachen Chapter 5 Fast Block Ciphers
Fichier Détails
| Cartes-fiches | 53 |
|---|---|
| Langue | English |
| Catégorie | Informatique |
| Niveau | Université |
| Crée / Actualisé | 21.03.2017 / 20.08.2017 |
| Lien de web |
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What are the requirements?
[9.1997.history.fastblockciphers, 2]
1. Block length of 128 bits
2. Key length of 128, 192 and 256 bits
Who are the competitors?
[9.1997.history.fastblockciphers, 5]
1. Rijn-dael by Rijmen and Daemen won
2. MARS by IBM
3. RCG by RSA
4. Serpent by Biham
5. Twofish by Schneier et al.
List them!
[others.fastblockciphers, 6]
1. IDEA by Lai and Massey
2. Blowfish
3. Khazad
4. Anubis
5. Serpent
6. Twofish
What are the characteristics?
[IDEA.others.fastblockciphers, 3]
1. First presented on Eurocrypt in 1990
2. Patented in Europe and USA
3. Non-commercial use is free
How do we define the blockcipher?
[modes.fastblockciphers]
Blockcipher with key K is defined as EK
List them!
[modes.fastblockciphers, 5]
1. ECB
2. CNC
3. OFB
4. CFB
5. CTR
What is the definition?
[ECB.modes.fastblockciphers, 2]
1. Ci = EK(Mi)
2. Mi = EK-1(Ci)
What is the definition?
[CNC.modes.fastblockciphers, 1+2]
1. Use non-secret initial vector C0
2. Ci = EK(Mi xor Ci-1)
3. Mi = EK-1(Ci) xor Ci-1
What is the definition?
[OFB.modes.fastblockciphers, 1+2]
1. Use non-secret initial vector Z0 = C0 and keystream Zi=EK(Zi-1)
2. Ci = Mi xor Zi
3. Mi = Ci xor Zi
What is the definition?
[CFB.modes.fastblockciphers, 1+2]
1. Use non-secret initial vector Z0 = C0 and keystream Zi=EK(Ci-1)
2. Ci = Mi xor Zi
3. Mi = Ci xor Zi = Ci xor EK(Ci-1)
What is the definition?
[CTR.modes.fastblockciphers, 1+2]
1. Use non-secret initial counter Z1 = C0
2. Ci = EK(Zi) xor Mi
3. Mi = EK(Zi) xor Ci
What is the definition?
[messageauth.modes.fastblockciphers, 3]
1. Modifying one pt must affect all subsequent blocks // CBC and CFB
2. Compute Cn for M=(M1,…,Mn)
3. If M is tampered by Oscar into M’ then Cn does not fit M’
What is the definition?
[sharingpassword.modes.fastblockciphers, 2]
1. Generate key K = k(name, password)
2. Store tuple (name, EK(password))
