# 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.

4,697 questions
Filter by
Sorted by
Tagged with
186 views

### Can we extract public key from signature created by RSA?

I know it's possible with ECDSA. How bout RSA?
44 views

### Symmetric and asymmetric encryption using the same encryption/decryption algorithm?

If we use the following notation: $$C = E(P, K_e)$$ $$P = D(C, K_d)$$ Where: $$E(), D(), C, P, K_e, K_d$$ are the encryption algorithm, decryption algorithm, ciphertext, plaintext, encryption key and ...
• 101
134 views

### How do I decrypt a key encrypted by my HSM under a ZMK?

I've generated a key using an HSM Thales PayShield and i have share it with a counterpart. I followed these steps: i generated key usign KG console command i use FK to form ZMK from clear components ...
252 views

### How to find the round key in AES 256

Can anyone explaine how to find the every 15 round key by the 64 hex digit master key of AES 256 please. I will be really greatfull
50 views

### Are asymmetric encryption and decryption same function? [closed]

In asymmetric key encryption, we have 2 functions, encrypt(m,k) and decrypt(m,k), and 2 keys, ...
• 9
30 views

### Is there a multi-key encryption and decryption algorithm that allows key revocation?

I have private data and I want to encrypt it to share it with some users who should be able to decrypt it. Therefore, I need multiple keys to decrypt it. But, I also want to be able to revoke a key to ...
96 views

### Securely computing the addition of n numbers owned by n people

Assume that we have n people each owning a secret number. Now we want to collaboratively compute the addition of all these numbers without anyone revealing their numbers. Then the result will be made ...
• 101
1 vote
175 views

### Why is static-static diffie hellman needed in Noise_IK?

TL;DR: Why is there a static-static diffie hellman in the Noise_IK handshake? Hi, I am currently trying to understand the WireGuard VPN protocol. As you may know, it uses the Noise_IK handshake from ...
• 13
38 views

### How many ciphertexts should attacker intercepts if he only knows the first 3 bytes of plaintext of each one?

Consider a system in which DES is used to encrypt messages in which the first three plaintext Bytes are known by the attacker. How many encrypted messages is it necessary to intercept in order to be ...
• 143
1 vote
342 views

### Stuck on Decrypting with RSA and SHA256 in Encryption Task

I'm working on solving a encryption task, and I'm a bit stuck. I want to clarify that I'm only seeking hints and not direct answers since I want to solve it myself. The goal is to solve it on my own; ...
• 111
1 vote
67 views

### Secure encryption in the presence of a keyservice

Imagine this scenario: On a particular PC is a service that provides cryptographic functions -- in particular AES-CBC and ECC (ECIES/ECDSA). The service provides access to a single key stored in an ...
• 113
486 views

### How does TLS 1.3 restrict the Diffie-Hellman parameters to ones that are known to be secure?

In previous versions of TLS, the choice of the Diffie-Hellman parameters was up to the participants. This resulted in some implementations choosing incorrectly, resulting in vulnerable implementations ...
1 vote
69 views

### Threshold Paillier encryption key generation time

I have used the threshold version of Paillier encryption without a trusted dealer in an application. I have tested the key generation phase with different security key sizes such as 80, 512, 1024, and ...
• 11
1 vote
104 views

### Issue with AWS Encryption SDK for JavaScript in Browser: 'Buffer is not defined' [closed]

I'm trying to implement AWS Encryption SDK for JavaScript in a browser environment within a React application. When I attempt to construct an instance of the encryption client using buildClient ...
1 vote
113 views

### AES CBC with random IV but key from PBKDF2 with same salt

TL;DR: Is encrypting data with AES CBC with random IV + PBKDF2 key using the username as salt safe? I have searched the internet, but I could not find a proper answer that encompasses the "AES ...
1 vote
106 views

### Enigma Questions: Eliminating the can't encode to itself flaw? Maybe not a flaw

I am currently writing a paper in my old age for the fun of it. I feel that the enigma machine had gotten a bad wrap for some of its flaws. I decided to write a machine simulation to see if I can ...
1 vote
213 views

### Forming ECC key (TLS) in X9.63 format

I am studying TLS handshaking by example a program tlse, which uses libtomcrypt library.I see that in line 5236 (link above) the program call libtomcrypt procedure ...
• 95
1 vote
77 views

### Cryptography particular block length valid message

I am new at cryptography and start to learn some terms. I just saw an question in the book and didn't got a clue about this question. Could someone can explain me the answer of this question? Because ...
• 31
260 views

### Are passkeys actually hardware keys or are they just reversibly encrypted keys secured by a hardware key?

Passkeys have this complicated QR code + Bluetooth dance to enroll a new device which seems like it ought to be securely creating a key on the device in a TPM. However the messaging around "sync&...
1 vote
72 views

### Is there a good website to circulate RFCs [closed]

I'm drafing an RFC for a low computation crypto algorithm, intended for low power bluetooth communication. Likely without a connection using advertisements only. It's going to include raw C code ...
101 views

### Are Schnorr's algorithm really subject to q-computer attacks?

I was wondering whether quantum-computers really break Schnorr's signature scheme. Schor's algorithm works via the quantum Fourier transform, which reveals the cycle time and thus phi. However, with a ...
66 views

I have built a small password manager desktop app using python. This app falls under the master-password model.The app connects to two databases stored locally. The first database stores the users ...
1 vote
299 views

### Can I use Argon2 to encrypt data?

Normally I use Argon2 to generate an encryption key, and then use AES to encrypt data with that key. Can I just set the hash size to be equal to the data size, set the associated data to a random ...
• 11
155 views

### Can you re-encrypt data without knowing what the data is or using PRE?

I'm currently working on a distributed consensus-based system. I currently give the system a private key through a threshold encryption model, and I want to be able to take some data encrypted with ...
• 21
73 views

### How can I send someone a large file safely without using key exchange protocols (for encryption)?

I recently took an exam where one of the questions was roughly the following: You need a specific way for sender S to send a large file M to a receiver R with their secret-public key pair, without ...
• 23
74 views

### Is a Pedersen commitment still secure when r is either 0 or 1?

Specifically if we know the $r$ takes values from the set $\{0,1\}$and $c=g^r*h^m$ does the hiding property still hold? I think I already managed to prove that the binding property holds due to the ...
• 23
242 views

### Best practices on implementing a password manager

I'm a dev new to security and cryptography. I'm writing a password manager and Time-based OTP combo in dart/flutter to use in multiple devices and platform for fun and use it personally for real. I ...
84 views

### Shortest encryption with URL-friendly character set

I need a way to encode a set of information in a way that the result would be as short as possible with a requirement of it being usable as part of URL string. I don't really care that much about ...
• 101
688 views

### Padding Oracle Attack - Decrypting First Block with Static IV

I'm trying to understand the exploitability of the padding oracle attack, which enables someone to decrypt and encrypt the contents without knowing the encryption key. Can encrypted data with the ...
95 views

### Hiding sum of vectors. Hardness based on CVP

This is the problem Let $\mathcal{L}$ be a lattice and $v_1,v_2,\ldots,v_n\notin\mathcal{L}$. Given the values $a_1,\ldots,a_n$ such that $$a_1=\lfloor v_1\rceil+v_2+\ldots+v_n$$ a_2=v_1+\lfloor v_2\...
87 views

### TPM - Ecc based encryption / decryption using the public key

Our device comes with a device certificate which was signed with our private registration authority (CA). The private key (type ECC) was generated on the device itself - to be more specific directly ...
• 786
166 views

### Double Ratchet Algorithm: Active Man in the Middle Attack without Root-Key or Ratchet-Key

I am currently studying the Double Ratchet Algorithm from Signal (link to the documentation). I stepped over a security issue which I was not able to find that it was mentioned anywhere. I assume that ...
• 308
15 views

### When can the types of data be distinguished during the addition of encrypted data to a deterministic encrypted data set with equal proportions?

This question is about adding new data with different proportions to a dataset with equal proportions for each type of data, and determining at what point the added data can be distinguished. For ...
• 31
72 views

### To prove equality/inequality of plaintexts of 2 ciphertexts encypted under different encryption schemes

We have 2 ciphertexts, one encrypted using Paillier and another encrypted under Elgamal encryption schemes. Is there a way to design ZK-proof to prove equality of the underlying plaintexts of these 2 ...
259 views

### What is the post-quantum security of encryptions schemes based on transpositions?

I know that if using Grover's algorithm to break a cipher, one would need to perform (2^[key space])^0.5 queries (the square root of the number of all possible keys). A simple transposition cipher ...
• 391
107 views

### In what way, does adding dimensions to lattice based cryptography decrease vulnerability to quantum computers? and why?

In RSA encryption, the larger the size of the prime numbers utilized for the creation of the public key, the more computational power is required in order to "Brute force" decryption. Does ...
110 views

### Does having more than one HMAC provide more information to the attacker?

Suppose $N$ many messages has been sent from $A$ to $B$ in this format: $\operatorname{HMAC}(K, C(i)) \mathbin\| C(i)$. Where $C(i)$ is some cipher-text encrypted with some secure algorithm using ...
407 views

### Is that possible for local p2p connection with encryption and remote p2p connection with encryption within the same application?

on the wiki page of Rustdesk, it states "the connection is unecrypted, please do not send us issue about this." for local direct IP. BUT, Rustdesk is intended "Virtual / remote desktop ...
123 views

### What is the result of not connecting the 1st register to the xor gate in LFSR?

I designed 8 bit lfsr in vhdl. According to mathematical theory, I xor processed the outputs of registers 1, 4, 5, 6 and 8 and connected them to the input of register 1. theory says that if I give the ...
61 views

### Storing length of encrypted data

I need to encrypt some user's data. However to make it more apparent to the user what data is stored in each key, I was thinking to also store the length of the actual data along the cipher. E.g. <...
• 121
1 vote
We use DES in cipher feedback mode (CFB) to encrypt a plaintext $m = m_1\mathbin\|m_2\mathbin\|\ldots\mathbin\|m_{100}$ into a ciphertext $c_1\mathbin\|c_2\mathbin\|\ldots\mathbin\|c_{100}$, where ...