2
votes
1answer
47 views

Calculate the security of a cascade cipher

I’m reading “The Security of Multiple Encryption in the Ideal Cipher Model” and I’m having a hard time understanding something. How do I calculate the bounds of cascade cipher from the following ...
1
vote
1answer
78 views

Why is Rijndael key length restricted?

Why is Rijndael restricted to key length in {128, 160, 192, 224, 256} bits (and not larger)? The algorithm looks to me like it would support an arbitrary-sized key (multiple of 32). The rounds ...
1
vote
1answer
37 views

Process of dividing 168bit key into 56bit keys in TripleDES

I used TripleDES so many times but never thought about this. In TripleDES it requires 168bit ...
3
votes
3answers
176 views

Effective security of block cipher – equal the key size, or half the key size?

The Wikipedia “Key Size” article states: The security of an algorithm cannot exceed its key length (since any algorithm can be cracked by brute force), but it can be smaller. … … … Most ...
1
vote
1answer
106 views

Can 64-bit “PRINCEcore” practically be brute forced?

There is a cipher called PRINCE proposed in ASIACRYPT two years ago. See the paper: “PRINCE – A Low-latency Block Cipher for Pervasive Computing Applications” The cipher divides the 128-bit key into ...
1
vote
1answer
857 views

AES key/ciphertext space sizes

This is giving me a brain ache now... If I have AES-128, block is 128 bit, then every plaintext (128-bit) can be encrypted to some ciphertext that is also 128-bit. This is the block size. But: 128-bit ...
3
votes
2answers
1k views

AES Key Length vs Block Length

This answer points out that certain key and block lengths were a requirement for the AES submissions: The candidate algorithm shall be capable of supporting key-block combinations with sizes of ...
4
votes
1answer
472 views

How were the AES key and block length subsets of Rijndael selected?

My intuition tells me it's a trade off between speed and security, but how did the standardisation process select these three seemingly arbitrary key lengths (namely, AES-128, AES-192, AES-256).
32
votes
4answers
13k views

What are the practical differences between 256-bit, 192-bit, and 128-bit AES encryption?

AES has several different variants: AES-128 AES-192 AES-256 But why would someone prefer use one over another?