Linked Questions

4
votes
4answers
2k views

Could a larger block size increase the security of the block cipher?

I want to know if a larger block size increase the security of the block cipher?
4
votes
2answers
1k views

Key recovery when AES ECB is used for short but repeated messages

My question is based on the specification of the protocol LoRaWAN and especially on the part 6.2.5 Join-accept message. It is said that the join-accept message is encrypted using AES ECB. This is (...
1
vote
2answers
848 views

Decrypting ciphertext that is missing a block

In the AES encryption, suppose that the key is known. The ciphertext is also known except for a block of the same size as the key. For example, the adversary knows $k, c_0, c_1, \dots, c_{n - 1}$; ...
2
votes
1answer
1k views

Encrypting decimal values with AES

I have a column in a database table called "Amount" that will store decimal values encrypted with AES. It's highly likely that the same amount will exist in multiple rows in the table and be encrypted ...
1
vote
4answers
536 views

Using a block cipher with timestamp instead of counter

I have a system where machine A sends updates to machine B. The updates are sent over the internet, where each update is a single UDP datagram. Machine A sends a local timestamp in each update (we can ...
2
votes
1answer
385 views

Is predictable ciphertext/plaintext bad?

I have a cryptosystem that I'm using for secure chat. It is using AES 256 (with RSA 2048 for key exchange). Would a predictable, and repetitively sent ciphertext plaintext compromise the ...
1
vote
1answer
799 views

AES-encrypted 128-bit null block: lookup table?

Let's say a 1MB file has many many consecutive null-bytes 128-bit blocks. Then, as AES works with blocks, the encrypted file will also have recurrent 128-bit-long patterns of ...
0
votes
1answer
950 views

Multiple AES/ECB encryptions of different data with same key all end with same pattern

We have used "AES/ECB/PKCS5Padding" with a 256 bit key. We encrypt different streams of data (blockwise) with the same key. Each encrypted stream ends with same pattern. What is the reason for this?

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