Questions tagged [encryption]
Encryption is the process of transforming plaintext using a cipher into ciphertext to make it unreadable to anyone except those possessing the key. Decryption is the process of transforming that ciphertext back into plaintext, using the key.
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Concerns about use of MAC in my specification
Here is the pseudocode for a routine I am designing:
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Why is CBC with predictable IV considered insecure against chosen-plaintext attack?
I just learned that using CBC encryption with an IV which is predictable is not secure.
From what I understand, using certain plain texts, and then guessing the IV that it uses, the attacker can ...
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Why is XEX not used instead of CTR?
As far as I know the only disadvantage that XEX has when compared to CTR is that you need a block cipher/permutation while CTR is fine with just a hash function. Meanwhile XEX offers the advantage ...
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Is there a practical way to crack an AES encryption password?
I heard that the fastest method to crack an AES-128 encryption, or and AES-256 encryption is by brute force, which can take billions of years. But I can't help thinking there's got to be a faster way. ...
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Relationship between generating elements given by cycles in Cayley graph
The strong RSA assumption is that the following problem is hard to solve.
"Given a randomly chosen RSA modulus $n$ and a random $z \in \mathbb{Z}_n^*$, find $r>1$ and $y \in \mathbb{Z}_n^*$ such ...
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What kind of attack would a 128 bit SHA-2 be vulnerable to and why?
With SHA-2 for hashing, using only the first 128 bits to create a 128 bit hash, what kind of attack would this be vulnerable to and why?
Since 128 bit encryption keys are secure, shouldn't a 128 bit ...
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In what way is XXTEA really vulnerable?
I'm looking at using the XXTEA algorithm to encrypt a small amount of data (say, less than 32KB) in the context of a software licensing algorithm. That is, we wish to make it difficult (not impossible)...
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Why is a public key insufficient to decrypt a message?
I'm curious about how E2EE encryption works, but the high-level descriptions I've been able to find aren't quite as clear as I'd like them to be. My current understanding is as follows:
Suppose one ...
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Why do we use encrypt-decrypt-encrypt (EDE) in 3DES, rather than encrypting three times?
I'm wondering why we use encrypt-decrypt-encrypt (EDE) sequence in 3DES (also known as DES-EDE, TDES or TDEA) with three keys instead of three times encryption (EEE) with three different keys?
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Is AES resilient to chosen plaintext with access to related keys (key expansion primitives)?
I'm interested in knowing whether a cryptosystem is broken given access to a few primitives.
$\DeclareMathOperator{\KEYEXP}{KEY\_EXP}$
$\DeclareMathOperator{\E}{E}$
Suppose that you have access to an ...
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How to bruteforce password from HMAC-SHA256 hash (if you have the key)?
Short of creating one's own script / program, is there an existing, readily available way of iterating through a list of potential passwords to find which one corresponds to a hash (HMAC-SHA256), ...
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When using CBC-ESSIV for disk encryption, why does the generation of IV require a hash then encryption instead of only one hash?
The CBC-ESSIV algorithm specifies how to calculate the IV to use for a given key (K) and sector number (S) as the following:
$$\text{IV} = \operatorname{Enc}(\operatorname{Hash}(K) , S)$$
https://en....
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Concrete Example of AND Gate Using Garbled Circuit
Most of the resources online like the wiki presents the beautiful idea of Garbled circuit in a rather unnecessarily abstract manner. This is the screenshot of Wiki's protocol:
What would be an ...
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How can I make sure non-open source programs are really using end-to-end encryption?
Without going deep into math, is there a way to make sure that non-open source programs like WhatsApp, FaceTime, Zoom, etc. are really using end-to-end encryption instead of just 'regular encryption' (...
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What is the fastest way to generate a truly random one-time pad without electrical or any other complicated device?
I want to generate a truly random one-time pad as fast as possible, but without the use of any electrical or any other complicated device. What is the fastest way to do that?
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Is bit encryption enough?
Assume that $\Pi$ is a secure PKE scheme (or other appropriate encryption schemes) with 1-bit message space. And it can be applied bit-by-bit to construct a many-bit encryption scheme $\Pi'$.
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What is the exact algorithm for encryption and decryption with hummingbird-1 cryptography?
I have really googled the entire internet but could not find a clear algorithm for hummingbird-1 cryptography.The problem emerges in the decryption module:
What is the initial value of state register ...
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Finding Private key in RSA with public key, cipher text and plain text
Is there a known 'non-brute force' method of determining a private key in an RSA system when all other parameters are know?
I found the values of a ciphertext ($C$), its corresponding plaintext ($P$) ...
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How to properly sign and verify using DSA? Can anyone spot my mistake?
The question that I am trying to answer is as follows:
10.14. The parameters of DSA are given by p = 59,q = 29,α = 3, and Bob’s private key is d = 23. Show the process of signing (Bob) and ...
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Unable to determine plaintext from ciphertext
Given the letter-number cipher: a=00, b=01, c=02, etc., encrypt the word 'hi' and decrypt its ciphertext using RSA. The public key is (5,35) and the private key is (29,35).
I know that 'hi' is ...
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does increasing the number of rounds in feistel increase the security [duplicate]
In feistel cipher , does it matter that number of rounds ? is using more rounds will give the best result?
or it's all about the key size ?
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keyboard communication protocol? [closed]
I'm analyzing the transmitted data from the apple Smart Keyboard to the iPad, and I have troubles arriving to a conclusion:
When I press a key, the keyboard transmit two blocks of data: the ...
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Symmetric versus asymmetric self encryption
I can encrypt my files with a symmetric encryption algorithm like AES, or with an asymmetric encryption algorithm like RSA or ECC (I encrypt my files with my own public key). No communication is ...
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Implementing ESignature and digital certificate
I'm having some issue understanding the mechanism of electronic signature and how implementing it
Here what I understood, correct me if I'm wrong:
(Client is here an android or ios device. Server ...
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I don't understand RSA encryption (specific questions)?
So I've been studying RSA for a class and I'm having a hard time understanding how it works.
Why do we choose the value of e such that e is relatively prime to the totient (as opposed to just being ...
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Unknown bit in the output of encryption of data using SIMECK32 cipher?
How is the unknown bits (annotated by red arrow in figure below) come in the OUTPUT after round 1 and round 2 ?
Following is the pictorial representation of SIMECK round function operation.
Ref: ...
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Are there any algorithms for which generating any zero-knowledge proofs is not practical?
It is related to my earlier question:
Can zkSNARK or other zero-knowledge proofs be used to proof message authenticity without revealing private key?
Are there any algorithms for which generating ...
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Can zkSNARK or other zero-knowledge proofs be used to proof message authenticity without revealing private key?
The situation:
Alice and Bob are exchanging messages encrypted by some known asymmetric encryption protocol. All their encrypted messages, as well as public keys are intercepted by Charlie.
Can ...
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Can an AES-GCM be cracked if the key is known but the nonce isn't?
I'm kind of new in this field and I've been trying to learn it.
I'm now facing an issue where I have a couple of packages encrypted with AES-128 GCM and I have the key that was used to encrypt these ...
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Does Encryption add difficulties to File Recovery?
Seems Yes. People always tell us, it is very hard (or almost impossible) to recover an encrypted hard disk.
But after a second thought. I think this is not true.
Given that we know the KEY, and the ...
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How to backup a secret encrypted by multi parties without revealing the secret?
I'm searching for a way to backup a secret that only the end user knows the information with 2 trusted hosts.
But trusted hosts shouldn't have access to secret at any time.
First basic version :
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Why are there standards of encryption?
Pardon me if this question seems a bit obvious, but if someone has a key to your encryption, knowing what type of encryption you are using (or running outputs against a lot of common encryption types) ...
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Which is the best algorithm for large scale file encryption other than AES?
I've been looking for a fast, powerful and robust algorithm for encrypting large files with authentication .
I would like to implement the algorithm on my own without using third party software. I've ...
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Alternative way to provision secret in Intel SGX enclave
I have a case where I have multiple clients (non SGX, assumed safe) and server(SGX based), talking over a network. I wanted to provision a shared (per client) key which is used to encrypt and decrypt ...
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Storing values under different keys (e.g. during key rotation)
If you are encrypting some secrets (database passwords, access tokens, etc).
When it comes to key rotation, you'll need to store those encrypted values twice, for a short period of time (under the ...
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Is there any existing obfuscation scheme that makes cipher text indistinguishable from plain text?
Suppose a totalitarian government (in the name of anti-terrorism / protection of intellectual property):
has outlawed encryption itself - encryption is only approved for cases where the state has ...
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Encryption with 2 symmetric keys and decryption with one key
Here is my use case:
I need to keep encrypted data in Hadoop. The data is encrypted with symmetric key that is being changed every half a year.
When data is retrieved it should be decrypted.
Lets ...
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How passwords are fed to key derivation functions?
Suppose I want to encrypt data, send it over the network, and decrypt it on the receiver side.
I know the elegant way to do this is by using a symmetric key to encrypt the data and an asymmetric key ...
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I'm trying to understand which cryptographic algorithm is this
I'm reversing a cryptographic algorithm. This is part of the encryption function translated to python (starting from assembly code):
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Explanation of $z^{-1}$ and $T_{1,2}$ within E0 Bluetooth encryption algorithm
I am trying to understand how E0 Bluetooth algorithm exactly works. I know that $y_t$ is the sum of $x_1$ to $x_4$ and can take values $0, 1, 2, 3, 4$. Also $S_{t+1}$ = $(y_t + c_t)/2$ and can be $\{0,...
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Name for a Ceasar Cipher that uses random offsets?
In a traditional Ceasar Cipher, you pick a specific offset such as "plus three" so that to encrypt each character of a message you count three letters up from the input and to decrypt you count three ...
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Research topics related to cryptography and Hamiltonian cycles
I am very interested in pursuing a research where I can show an application of Hamiltonian cycles in Cayley graphs of some group such as reflection groups to the field of cryptography.
But currently ...
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Perfectly secure and indistinguishability property
I'm studying cryptography for my university course, but some doubts arose from reading a book.
In this book the author says:
"Now we present another equivalent definition of perfect secrecy. This is ...
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XORing a nonce with a ciphertext vs XORing a nonce with plain text and then encrypt
Consider a situation where a symmetric key encryption (such as AES) is used to encrypt the plain text. Moreover, a nonce is used to ensure that old communication cannot be used to perform a replay ...
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DES/AES invertibility
My professor has posted a couple of practice questions that so far I haven't been able to find the answer for and I was hoping you could help.
DES would remain invertible—it would still be ...
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Is CBC really dead?
I developed a p2p-app in C# which sends and receives encrypted text messages (50kB). For encryption, my app uses 128-bit AES in CBC cipher mode. For each message it uses a new randomly-generated IV.
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What's the actual difference between RSA encrypting and Descrypting and RSA Signing? [duplicate]
this question arised because I'm working with Windows' CNG library and it has 4 functions for RSA:
BCryptEncrypt (private key, message)
BCryptDecrypt (public key, message)
BCryptSignHash (private key,...
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RSA Decryption: Doubts: knowing p or $\phi(n)$ can lead to find private exponent?
I have some doubts about RSA (the public key $n$ and $e$ is public):
Note $n = pq$ and $\phi (n) = (p-1)(q-1)$
1) Say if some hacker knew $p$, why would it be easy for them to find $q, \phi (n), d$?
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is using secp256k1 curve for ECIES considered safe?
I read SafeCurves it indicates Secp256k1 is not SafeCurve by their standards but bitcoin and ETH use it in their blockchain.
I researched more and figured out that using Secp256k1 ECDSA(singing ...
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Cryptography question(s) about RSA [duplicate]
In the real world, it's best to use at least two or more algorithms to encrypt data.
From what I know, RSA acts as a wrapper to transfer data safely across web systems or API(s), or acts as a wrapper ...
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