Linked Questions

1
vote
3answers
224 views

Any benefit to writing a message as a mix of 2 languages before encryption?

For example, imagine a message that is a mix of Japanese and English words; Japanese in unicode, English in ASCII. Japanese doesn't use spaces between words. The sentence structures, anything ...
2
votes
3answers
892 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....
4
votes
3answers
264 views

Does complicating a flawed algorithm make it secure?

It's a basic question I guess, but I don't know the answer and I don't think that anyone asked it. Suppose I built a system, it relies on MD5 for security, suddenly I read am article on how easy are ...
7
votes
1answer
423 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 ...
3
votes
1answer
2k views

How vulnerable is one-time pad (OTP) encryption, if the OTP is used twice, with a random substitution scheme

After reading up on the one-time pad (OTP) encryption method, I could see how it would offer unbreakable encryption if used properly. Moreover, I looked at how the OTP could be broken if the OTP-key ...
5
votes
2answers
357 views

Fast post-processing for broken RDRAND

Let's assume that the Intel RDRAND instruction does not return fully random numbers, e.g. because it has been engineered with a backdoor for the NSA. If the Intel RDRAND instruction is used directly ...
6
votes
1answer
953 views

What is 'key agility' in relation to symmetric-key encryption?

I sometimes see, in discussions of symmetric ciphers, reference to the 'key agility' of a particular algorithm. It seems to be related to the difficulty of switching encryption keys, but I don't ...
3
votes
1answer
1k views

How do you test the security of your cipher?

I got asked this question and I didn't know what to answer. How do you test the security of your cipher? What comes to my mind now would be to test it with famous attacks: padding attacks, ...
1
vote
2answers
461 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 $k, c_0, c_1, \dots, c_{n - 1}$; ...
1
vote
1answer
278 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 ...
3
votes
3answers
288 views

Allowing the user to choose the hashing formula at the registration

I was thinking of a potential new way to increase someone's account security. The idea was allowing the user to choose one of the hash formulas available in the software (example: "MD5", "SHA512" and ...
0
votes
2answers
325 views

What is the correct test/s to do in asymmetric algorithms to test their security?

I would do some test for evaluating security in asymmetric algorithms such as RSA and ElGamal to evaluate which of both are safer. The basic problem is that I need to test the security of some ...
0
votes
1answer
316 views

Choosing encryption algorithms and encryption protocols in military systems

Militaries use their own cryptographic algorithms, those of a private third party, or ones that are openly available. But fear of a backdoor having been planted in publicly-available encryption ...
-2
votes
1answer
573 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? ...
0
votes
1answer
294 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 ...

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