Linked Questions

15
votes
2answers
23k views

Using ECB as RSA encryption mode when encrypted messages are unique?

As I understand, ECB should not be used as encryption mode unless you are encrypting single blocks of data which are always unique and only are encrypted once. I have a collection of ids represented ...
6
votes
9answers
758 views

Soft question: What are examples of beautiful proofs in cryptography? [closed]

These may include any proofs, reductions, constructions, etc. For example, simple solutions to problems which at first sight seem difficult. Elegant construction that hide deep mathematical concepts, ...
-2
votes
1answer
81 views

What exactly is the problem with using electronic codebooks as a block cipher mode [duplicate]

I was wondering why it is a problem with using ECB as a block cipher mode
391
votes
13answers
144k views

Should we MAC-then-encrypt or encrypt-then-MAC?

Most of the time, when some data must be encrypted, it must also be protected with a MAC, because encryption protects only against passive attackers. There are some nifty encryption modes which ...
7
votes
3answers
8k views

Is it possible to find the key for AES ECB if I have a list of plaintext and corresponding ciphertext?

Assume I have a list of plaintext text and its corresponding ciphertext which was created using a specific key with AES in ECB mode. Can I recover that key? If, how big does the list of plaintext ...
25
votes
2answers
12k views

Can someone explain the ECB Penguin?

I've seen the ECB Penguin used to demonstrate why ECB is not a recommended method of encryption, but I do not understand how this translates to text or passwords. Aren't the people who create these ...
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 $k, c_0, c_1, \dots, c_{n - 1}$; ...
10
votes
4answers
4k views

Are there any benefits to using ECB over CBC?

From what I have understood about ECB and CBC, CBC is far better as it doesn't reveal any pattern. There have been several questions here about how ECB is bad: Should I use ECB or CBC encryption mode ...
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 ...
6
votes
1answer
34k views

Why is padding used in CBC mode?

I am newbie to CBC crypto: When I try decrypt the cipher text to recover the plain text, things are not going smoothly as I face some issues in the decryption process with padding and not obtaining ...
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?
1
vote
2answers
4k views

Brute force, get AES keys by multiple plain-texts with their cipher-texts

I know that the encryption is AES, and I have multiple plain-texts with their cipher-texts, I don't know the encryption mode (ECB, CFB, etc ...) actually, but I know that the keys and the IV Key (if ...
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 ...
5
votes
3answers
2k views

Is it possible to decrypt the 2nd byte of AES-256-CFB-8 ciphertext without decrypting the 1st byte?

I am stuck with AES-CFB decryption. Assume I encrypted plaintext helloworld (10 bytes) using AES-CFB. Now I want to decrypt the second byte ...

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