Linked Questions

0
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0answers
39 views

Can we bound adversarial power in terms of total entropy in universe? [duplicate]

The strengths of various cryptographic primitives are often explained (though not defined) in terms of how long it would take to break under the current best known attacks. For example, apparently the ...
39
votes
10answers
10k views

Differences between industrial and military cryptography

Industrial and military cryptography should follow the same basic rules, but what does make them different is: Higher key length, protocols unknown to the civilian world, and perhaps unique methods ...
42
votes
6answers
32k views

Why is AES resistant to known-plaintext attacks?

At least it's my understanding that AES isn't affected by known-plaintext. Is it immune to such an attack, or just resistant? Does this vary for chosen-plaintext?
29
votes
3answers
4k views

Dropbox Password security

Dropbox have recently published How Dropbox securely stores your passwords Is this really more secure than using bcrypt with a complexity of 11 or 12 ? The password "chain" is secure as its weakest ...
15
votes
4answers
20k views

Is password-based AES encryption secure at all?

For a few years I have put all my passwords in a text file and encrypted that file with a password using a software solution (Axcrypt) which uses AES-128. The password is not really strong, but I ...
15
votes
2answers
3k views

Calculate all possible keys for AES 128 encryption to exploit hardware encryption

Some background: I am using the MicroChip ATAES132a for hardware encryption/decryption. The ATAES132a is very configurable and can be misconfigured in such a way that the encryption/decryption will be ...
11
votes
2answers
17k views

Does SHA-1024 hash exist?

Does SHA-1024 cryptographic hash function exist similarly to SHA-512? If not, what's the reason for that? Links: SHA-2 at Wikipedia SHA-3 at Wikipedia
10
votes
3answers
1k views

1 Billion Bit Encryption?

So, browsing through YouTube, I stumbled on this video interview of John Draper (Captain Crunch), one of the first "hackers". He talks for about 3 minutes (until 27:48) about his home rolled ...
2
votes
4answers
660 views

Why can't we give block ciphers larger keys?

I have limited math's knowledge so sorry if this question sounds stupid. I saw many people complaining about AES, Twofish and Serpent that these ciphers all could be crackable in the near future and ...
14
votes
2answers
48k views

Twofish vs. Serpent vs. AES (or a combo)

I've seen some posts and info online, but they are from 2009, 2010, 2011 or 2012, which is 3-6 years ago, which is a very long time. So I'm looking for an up-to-date answer about which of these is the ...
5
votes
4answers
24k views

How long would it take to brute force an AES-128 key?

How long would it take to crack a AES-128 key using the most advanced technology currently available? The hardware can be anything, be it a high-performance CPU, GPU or even FPGA?
15
votes
4answers
2k views

How is the quality of a password calculated and what does it mean?

While using Keepass and using it to generate random passwords, I always have noticed the "quality" section but truthfully have never known what it actually means. So my questions are; How much ...
10
votes
5answers
2k views

What is the most secure ECC Curve?

I have for a while used Koblitz curve (sect571k1), in ECDH and ECDSA. But I have started wonder if it is the most secure. I prefer security over efficiency. So the curve doesn't have to be the most ...
6
votes
4answers
716 views

Is there a proof for showing any cryptogram is crackable?

I commonly hear statements along the lines of "all cryptograms are crackable - it's only a matter of time". Is there a proof to show that any cryptogram is "crackable"? The proof may be of a more ...
2
votes
2answers
1k views

Is this test result sufficient to steer clear from this RNG for cryptographic applications?

I'm not really interested in this PRNG. I'm more interested in understanding what it takes to fail the security threshold for cryptographic applications. I'm taking the C PRNG as an example. ...
7
votes
1answer
2k views

Is the cipher “Kalyna” with a 512-bit key length more secure AES with a 256-bit key?

Recently I have found out that Ukraine has its own symmetric encryption algorithm "Kalyna". Developers of this algorithm said that their algorithm is more secure than AES because of longer key length ...
3
votes
1answer
24k views

Is SHA-256 safe and difficult to crack? [duplicate]

I am trying to crack a SHA-256 hash but I am not sure how to approach this in an efficient way. The following is known of the original non-hashed content: 64 characters long only consists 0-9 and a-z ...
4
votes
3answers
1k views

How likely is a AES KDF bypass?

So I was wondering about some alternative attack scenario which I thought of when I started to understand KDF's . So lets say you have a cipher like AES and a strong KDF . And the legit user uses a ...
4
votes
2answers
10k views

ECDSA with SHA256 and sepc192r1 curve: Impossible, or how to calculate $e$?

I need to use ECDSA as the signing algorithm and SHA256 for hashing the message. I'm running into troubles verifying the signature calculated on two different platform (one is BouncyCastle, another ...
4
votes
2answers
6k views

Algorithm for generating OAuth tokens

I'm trying to find a good algorithm for generating authorization codes, access tokens and refresh tokens in an API. Currently, I am looking into the following setup: Tokens are generated using the <...
1
vote
1answer
2k views

Why is AES unbreakable?

Why is it said that AES is unbreakable? Brute force attacks would take years to crack it, so is it possible to crack it if the computational speed of machines increase in the following decade?
3
votes
1answer
2k views

ECC keys vulnerable to brute force attack?

I have started learning about Elliptic curve cryptography. Since the key size required in ECC is relatively lesser than the key size in RSA to provide the same amount of strong encryptions, I wonder ...
5
votes
1answer
801 views

Can there be a need for 1024-bit (symmetric) encryption?

I think we are all aware of the CAESAR-competition. Now the aim of this competition is to select a (portfolio of) winner(s) which provide authenticated encryption. I'll now assume that the results ...
2
votes
2answers
663 views

Diffie-Hellman key exchange - why is modulo operation necessary?

Could someone explain why it's necessary to have the modulo operation in the Diffie-Hellman key exchange? Let's imagine we do DH without the modulo operation ($A = g^a, B = g^b$). Would that not work,...
6
votes
1answer
1k views

AES128 and 256 Microsoft Office

I realise this is kind of a basic question but its one I must have an answer too. One of the questions I have had thrown at me recently is why are we still using the default of AES128 when password ...
2
votes
3answers
783 views

How much processing power should you assume an attacker has?

The answer to this question says that you should assume an attacker can do one billion operations per second: Key Size for Symmetric Homomorphic Encryption Over the Integers Is that a single attacker ...
-3
votes
2answers
834 views

Breaking Ransomware encryption

Recent news reports show that the UK's NHS (Nation Health Service) has suffered a major ransomware attack which is also affecting other parts of the world especially Spain and Russia, the effect is to ...
-4
votes
1answer
2k views

Is AES256 the most secure encryption algorithm available at the moment? [closed]

I have had to edit this question because it was too broad (sorry didn't realise that was not allowed...), so, lets go with: Is AES256 the most secure encryption algorithm available at the moment? If ...
5
votes
1answer
2k views

Can cryptocurrency mining devices be used for cryptanalysis?

In the past year or so we have seen production of ASIC devices designed for mining of cryptocurrencies. These devices can perform SHA256 hashing at rates much higher than was seen in the past and are ...
2
votes
2answers
330 views

Is there a metric (term) for work required to decrypt a public key?

Any public key decryption can be decrypted given enough time and computing power. Is there a metric or term for this? Something like it would require on average 2^43 1024 bit hashes to find private ...
1
vote
1answer
1k views

Creating a random password based off of a prime number

So I am making an application that basically creates strings that must be encrypted before they are stored on a user's device. If the user blindly starts running the application without creating a ...
2
votes
1answer
395 views

Is there a truly safe signing algorithm?

After reading this question, I'm pretty shaken up. A determined attacker with $100 in loose change can crack any RSA key in a couple of hours. After believing that these algorithms would take millions ...
3
votes
2answers
312 views

can a weak cipher in a cascade weaken the result?

So i am a real beginner . And I use AES(TWOFISH(Serpent))) for my veracrypt file . So I asked myselfe a Question : When a Cascade is made the Key is split in parts for each algorythm . So if We ...
1
vote
1answer
1k views

Using HMAC-SHA256 with short passwords and sliced outputs for short-lived secure hashing

I don't have much background in cryptography, so forgive me if I'm using the wrong mathematical terms to explain my needs. Following this question, I learned that taking a random secret 16-bytes <...
3
votes
1answer
559 views

Order of multiple encryption algorithms

as you can see on image above, in VeraCrypt you can select either Serpent -> Twofish -> AES or ...
0
votes
2answers
890 views

How to calculate a private key from public key on elliptic curve? [duplicate]

Provided, that you have to multiply a well known G by the private key to obtain the public key, why not keep adding G to itself until you reach the public key. The private key should be the number of ...
4
votes
3answers
862 views

How confident can we be that nobody will crack a 128-bit key?

In a context involving a block cipher like AES-128, excluding quantum computers, cryptanalytic breakthrough on AES and implementation attacks (poor TRNG, DPA..), and wrench, how confident can we be ...
2
votes
1answer
163 views

Why is 128-bit considered “medium term” security?

Why is 128-bit encryption considered good enough for medium term security only? How is expected to be eventually broken? Quantum computing or brute force attack?
3
votes
2answers
223 views

Recovering key in AES - Infinitely many known plaintext ciphertext pairs

Is it possible to recover key/algorithm in AES encryption more efficiently than via brute force given attacker has access to arbitrarily many plaintext ciphertext pairs. If so, are there other known ...
-2
votes
1answer
339 views

SHA256 - Which is less impossible?

To generate every possible hash would be ... impractical. To work backwards from any given hash is also incredibly labor intensive. Of the two, which is less impossible? Why?
0
votes
1answer
263 views

Perfect secrecy of block ciphers

Is it right that all block ciphers don't provide perfect secrecy like AES? If it's true, how can we prove that? If it's not true can you tell me a sample? Any reference or guidance would be ...
1
vote
1answer
150 views

Encryption using matrix transformations

I have been thinking lately about a block cipher which takes a block of bits and arranges them in a square matrix. Then defining transforms on submatrices of the square matrix to scramble the bits. ...
0
votes
2answers
316 views

Can an AES-256 key be generated for a large number of cribs? [duplicate]

I have a question in regards to Ransomware type viruses. I know that a number of these viruses use the AES-256 algorithm to encrypt user's files using a randomly generated key. I work in IT support ...
0
votes
2answers
128 views

Is there a way of increasing the time to brute force a cipher, but by increasing the ciphertext size instead of the key size?

If you have a symmetric-key algorithm that is limited to using a small key size (say 40-bits) is there any way you could increase the resistance to brute force attacks without increasing the key size? ...
0
votes
1answer
205 views

How can I study the math behind cryptography? [closed]

I am a junior in high school and I am currently studying algebra 2. Where can I go to learn about the mathematics behind cryptography? I have a very basic knowledge of cryptography, but I am really ...
0
votes
0answers
225 views

What is the danger if a non-prime is chosen for RSA? [duplicate]

I was reading this question about generating primes for RSA keys. The answers point out that most implementations of of the algorithm use probabilistic prime-ness checking algorithms. The answer by @...
3
votes
2answers
56 views

Does a thermodynamic limit on key search apply to quantum computers?

There is (or at least was) a thermodynamic reasoning that any form of brute force key search would require an energy at least $k\,T$ per key tested, where $k$ is Boltzman's constant and $T$ the device'...
1
vote
1answer
68 views

Indeterminate Message Validity as a Noise Source in High Volume Channels

Question Rephrased: Does randomisation of valid and invalid messages in a high volume channel add security? Scheme: valid messages are identified by a pre-shared random number sequence and noise- ...
0
votes
1answer
61 views

Key generation algorithm based on bytes in a drive [closed]

I am a novice cyber security student and thought of a way to generate a random cryptographic key. The algorithm works as follows: Get the size (in bytes) of every file in a directory (drills down ...
1
vote
0answers
43 views

Maximum security strength in bits of ISAAC cipher?

Wikipedia claims key length can be very big in this cipher, so I assume it can offer a million bits of security provided entropy of key is the same? Of course I can SHA-256 hash the key to allow any ...