Linked Questions

2 votes
1 answer
421 views

Choosing encryption algorithms and protocols in military systems

Militaries use their own cryptographic algorithms, those of a private third party, or ones that are openly available. However, fear of a backdoor having been planted in publicly-available encryption ...
R1w's user avatar
  • 1,960
1 vote
2 answers
2k 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 $k, c_0, c_1, \dots, c_{n - 1}$; ...
Alireza's user avatar
  • 19
1 vote
3 answers
9k views

Writing your own Encryption algorithm?

Simple answer (and I know this is a simple yes or no) is it possible to write an encryption that is 100% uncrackable, as long as I keep certain parts private? It's just for personal use. I'm a ...
Jan Sweet's user avatar
7 votes
1 answer
457 views

Does a conditional statement depending on a round number introduce timing attack problems?

In a cryptographic implementation I’m playing with, there’s a round function which includes a conditional if statement. Stripping the superfluous stuff, the C ...
e-sushi's user avatar
  • 17.9k
-2 votes
1 answer
1k views

Is it possible to attack an SHA-256 hash seeded with PHP’s mt_rand function?

Is it possible to attack this construction if the attacker only knows the hash? ...
James Walker's user avatar
1 vote
4 answers
364 views

Including the next random One Time Pad as part of the encoded message?

I've tried to do something very simple here, which is to encrypt a message with a one-time-pad (OTP) and include the next OTP as part of that same encrypted message. i.e. The first message consists of ...
Sci's user avatar
  • 21
2 votes
4 answers
2k views

An unbreakable book cipher?

In a recent press interview, a former terrorist of the 1970s described the cipher his group used to communicate. He claimed that method was unbreakable and I wonder if cryptographers today would agree....
dingowens's user avatar
0 votes
2 answers
217 views

Key vs Algorithm when applied to Enigma

I've just been reading the Why should I make my cipher public? question and answers on this site. I understand Kerckhoffs's principle, but I'm unsure exactly how this applies to Enigma - i.e. where ...
Adrian K's user avatar
  • 187
0 votes
2 answers
2k views

What are the exceptions to Kerckhoffs's principle?

Kerckhoffs's principle: A cryptosystem should be secure even if everything about the system, except the key, is public knowledge. Yet the following are three exceptions:- NSA Suite A cryptographic ...
Paul Uszak's user avatar
  • 15.5k
2 votes
2 answers
171 views

Is cryptographic function used in MAC/HMAC public knowledge?

I would like to store password digests in structure that contains information how digest were generated; There will be concatenated these three values: {Name} of hashing functions used for computing ...
jnemecz's user avatar
  • 155
-5 votes
2 answers
458 views

Ignorant Biologist in need of AES-128 CBC PKCS5 encryption key

I'm a biologist frantically trying to understand the world of cryptography overnight for research- please ignore my ignorance. I was given a large body of text to crack that is encrypted with AES-128 ...
Boi WUT's user avatar
177 votes
7 answers
139k views

Why can't we reverse hashes?

First off, I know hashes are 1 way. There are an infinite number of inputs that can result in the same hash output. Why can't we take a hash and convert it to an equivalent string that can be hashed ...
Hello World's user avatar
  • 1,887
0 votes
1 answer
817 views

Is my high school cryptography/steganography science fair project practical?

I'm a 12th grade student interested in a science project in cryptography and steganography for my school's science fair. I chose this path of computer science partly because my coding skills are weak (...
Ingrid's user avatar
  • 19
0 votes
1 answer
447 views

Is flipping the bit belonging to encryption?

Just a simple question about encryption. If we have an image, we transform into a bits and we get 1001001... Then, I flip the bits into 0110110... manually. Can I said that I have done an image ...
alvin19's user avatar
  • 33
1 vote
1 answer
309 views

Value of new symmetric key algorithm

When I was in grad school, I invented (discovered?) a new PRNG algorithm. This algorithm has an infinite period length (given infinite memory). This in itself cannot be new, because all you need to ...
Jacob Levinson's user avatar

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