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Suppose I capture encrypted data that I want to decrypt. Could I use a server farm to decrypt?

For argument's sake, let's say that I'm a bad actor who produces malware. I've infected around 10,000 computers and smartphones with my malware, which runs in the background and can be used to make ...
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Vulnerability of low value generated key

I have read here that Elgamal is resistant to brute-force attack, because the group to where the key is selected is very large. But since the key generation is random, (i assume)there is a chance that ...
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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 ...
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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. ...
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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'...
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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. ...
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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 ...
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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 ...
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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 ...
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After reading this question, I'm pretty shaken up. A determined attacker with $100 in loose change can crack any RSA key in a couple of hours. After believing that these algorithms would take millions ... 2answers 1k views How to calculate a private key from public key on elliptic curve? [duplicate] Provided, that you have to multiply a well known G by the private key to obtain the public key, why not keep adding G to itself until you reach the public key. The private key should be the number of ... 1answer 3k views Is AES256 the most secure encryption algorithm available at the moment? [closed] I have had to edit this question because it was too broad (sorry didn't realise that was not allowed...), so, lets go with: Is AES256 the most secure encryption algorithm available at the moment? If ... 1answer 335 views Perfect secrecy of block ciphers Is it right that all block ciphers don't provide perfect secrecy like AES? If it's true, how can we prove that? If it's not true can you tell me a sample? Any reference or guidance would be ... 3answers 1k views How confident can we be that nobody will crack a 128-bit key? In a context involving a block cipher like AES-128, excluding quantum computers, cryptanalytic breakthrough on AES and implementation attacks (poor TRNG, DPA..), and wrench, how confident can we be ... 2answers 910 views Diffie-Hellman key exchange - why is modulo operation necessary? Could someone explain why it's necessary to have the modulo operation in the Diffie-Hellman key exchange? Let's imagine we do DH without the modulo operation ($A = g^a, B = g^b$). Would that not work,... 3answers 2k 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 ... 4answers 793 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 ... 1answer 368 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? 4answers 33k 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? 2answers 133 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? ... 1answer 72 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- ... 1answer 65 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 ... 2answers 949 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 ... 1answer 1k views Choice between AES-128 and AES-256 for password protection in MS Office Why are we still using the default of AES-128 when password protecting a Microsoft Word document. My answer is and always has been - because its good enough and MS don't recommend changing to AES-256. ... 2answers 355 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 ... 2answers 249 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 ... 4answers 3k 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 ... 4answers 23k 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 ... 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 ... 1answer 31k 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 ... 1answer 590 views Order of multiple encryption algorithms as you can see on image above, in VeraCrypt you can select either Serpent -> Twofish -> AES or ... 1answer 177 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? 0answers 46 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 ... 2answers 340 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 ... 5answers 3k 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 ... 1answer 276 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 ... 1answer 3k views ECC keys vulnerable to brute force attack? I have started learning about Elliptic Curve Cryptography (ECC). Since the key size required in ECC is relatively smaller than the key size in RSA (to provide the same encryption strength), I wonder ... 2answers 7k 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 <... 3answers 953 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 ... 1answer 876 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 ... 0answers 312 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 @... 1answer 2k 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 ... 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? 2answers 53k 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 ... 3answers 2k 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 ... 2answers 19k 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 2answers 11k 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 ...
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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 <...