Linked Questions

22 votes
5 answers
9k views

Is there a bulletproof way to know a file has been successfully decrypted?

I am wondering whether there is a bulletproof way to know if one is successful in decrypting a file. As an example, say I encrypt a text file and protect it with a 3 letter password. I use brute ...
untreated_paramediensis_karnik's user avatar
5 votes
3 answers
1k views

Theoretical Approaches to crack large files encrypted with AES

I have a large file (> 200 Gb), that I encrypted a while ago with AES-256-CBC. The file itself is a tar which I ran through ...
Sumuk Shashidhar's user avatar
3 votes
1 answer
170 views

How much information do I leak if I upload multiple ciphertexts with cleartext overlaps?

Suppose that $t_1, t_2, \ldots, t_n$ are my clear texts. Suppose that for any $(i,j) \in \{1,2,\ldots,n\}^2$, $t_i$ and $t_j$ only differ in, say, the 1st $m$-many characters. Finally, suppose that I ...
caveman's user avatar
  • 573
3 votes
1 answer
1k views

AES-128 (CBC) brute force given 90+ rightmost bits of key, known IV and Ciphertext?

Given: Known ciphertext (in hex) (ciphertext is the exact length of the message (i.e. non-padded). It is known that the cipher was developed using CBC. There is one and only one ciphertext message ...
RAnderson's user avatar
2 votes
4 answers
348 views

Is an invulnerable code possible (including brute force attack)?

If I double encrypted a text with for example AES wouldn't it be invulnerable to bruteforce attacks due to the computer not knowing when it has reached the plain text? Plain text->1st layer of ...
david david's user avatar
2 votes
1 answer
428 views

Attack on a Feistel Cipher given the key and half of the ciphertext

Consider a classical Feistel Cipher, with the round functions given and the keys used in the ciphering process. Is it possible to reconstruct the original data if half of the ciphered text is given? ...
Salsifis's user avatar
  • 123
2 votes
2 answers
124 views

Using the MAC to verify if Cipher Only attack has succeeded

I am working on an experiment to compare the efficiency of brute-force attacking block ciphers like AES and DES with reduced key sizes for different programming languages and library implementations. ...
Matt's user avatar
  • 21
1 vote
2 answers
571 views

Known Plaintext attacks using standard greetings etc

In all modern ciphers, even if one bit of input changes, then half of the output will change because of diffusion. Considering this, how exactly will knowing standard salutations, etc. ("Hello ...
user93353's user avatar
  • 2,295
1 vote
1 answer
108 views

When attacking keyed algorithms, how is it known when the output is correct?

I've been reading a little bit about cryptanalysis, and I'm wondering how attacking algorithms that work on keys is performed. It's obvious how algorithms like MD5 are attacked, in pseudocode: ...
tira's user avatar
  • 13
1 vote
1 answer
439 views

What are those RSA Challenges, DES Challenges and RSA Factoring Challenges

Can someone explain the differences between the DES challenge, the RSA challenges, and the RSA factoring challenge? What were the aims? I think the factoring challenge was to encourage research, the ...
george s's user avatar
1 vote
1 answer
1k views

Understanding LFSR stream ciphers and the content scrambling system

I'm a little confused over how exactly Linear Feedback Shift Registers (LFSR) work, I kind of get it, but not really, can someone help me understand it? I know it XORs bits in a loop against some mask,...
Anan's user avatar
  • 65
0 votes
1 answer
231 views

Brute force strategy

I am a beginner in this field, and I was thinking about brute force strategies to break symmetric key encryption. Let's say we have a block cipher in CTR mode and the key is 56 bits in size. What ...
anon's user avatar
  • 1
0 votes
2 answers
105 views

Is a larger block size less secure against a brute-force known cipertext attack?

Suppose a ciphertext $c$ was encrypted from plaintext $m$, and we know something about the form of $m$; say, for example, that $m$ is English text. We can attempt to brute-force $m$ from $c$ by ...
Jacob's user avatar
  • 103
0 votes
0 answers
44 views

Algorithms for reducing the scope of a brute force attack on a cryptosystem? [duplicate]

I understand that during a brute force attack on a cryptosystem, an attacker is left with many, many, junk files, some which are partially readable (depending on the crypto algorithm used), and 1 ...
Kevin DeCara's user avatar
0 votes
0 answers
161 views

Can I and How Decrypt this Online

Although I had a security course in school a long time ago, I am effectively new to cryptography. I have an encrypted text, the encryption key of 44 characters, the encryption method, (Fernet, which ...
Chozang's user avatar
  • 101