Linked Questions

3 votes
4 answers
11k views

Is a Mersenne-twister cryptographically secure if I truncate the output?

I want to create an online roulette game. Is it OK if the PRNG is seeded only once, when the user starts the game, or is it recommended to re-seed sometimes during game? Maybe just seeded once a day ...
user avatar
3 votes
3 answers
298 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 ...
GiamPy's user avatar
  • 133
3 votes
1 answer
3k 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 ...
Horst's user avatar
  • 143
3 votes
1 answer
2k 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, ...
David 天宇 Wong's user avatar
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
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
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
2 votes
1 answer
730 views

Inverting One-Way Functions

One of the conditions that a one-way function has to satisfy is the following: $$Pr[A(f(x))\in f^{-1}(f(x))] \leq negl(n)$$ Now, suppose that we have the following function that's not one way: $$f(x)...
GraceTone's user avatar
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
1 vote
3 answers
630 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 ...
Just Someone's user avatar
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
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
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
1 vote
0 answers
71 views

In symmetric searchable encryption are the algorithms public? [duplicate]

If a user (other than the data owner) possesses the secret key in symmetric searchable encryption scheme are they able to run the trapdoor algorithm, or is this not publicly available?
crypto1's user avatar
  • 11
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

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