# Questions tagged [rsa]

An asymmetric (e.g. public-key) cryptosystem, based on modular exponentiation with big exponents and modulus. RSA can be used both for signature and encryption with proper paddings.

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### Commitment schemes for arbitrarily large integers

My question is about commitment schemes for arbitrarily large integers. One scheme I know uses groups of unknown order (RSA or class group) and depends on the strong-RSA assumption. You chose a random ...
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### An “unsafe” curve over RSA? [duplicate]

I'm implementing a token server and considering backing them with ECDSA. The options from the library I'm using expose the NIST curves P-256, P-384, and P-521. The safe curves site does not list P-521,...
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### Why do we use groups, rings and fields in cryptography?

I'm a student of Masters in Cyber Security. I have a habit to understand things from their first principles (at the very beginning). Kindly use any simple mathematical example to answer because I have ...
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### Are GPUs inefficient for calculations on big numbers? Is RSA and EC cypto generally done on CPU only?

Looking specifically at RSA and EC algorithms which imply doing operations on integers >= 256 bits (>> 64 bits), I have noticed (from my limited experience) that 99% of the software for ...
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### Request for a zero-knowledge proof (or hint)

I want to design a zero-knowledge proof (ideally a NIZK, but could be a sigma protocol) so that Alice can prove that a certain encryption contains a value that has been signed by a certain key. More ...
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### RSA decryption time

I'm currently trying to create a lua script that can handle encrypting and decrypting using RSA, but when decrypting, the program takes an extremely long time, whilst when encrypting, the program is ...
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### Do perfect squares count as valid moduli for an RSA semi-prime?

The question is pretty self-explanatory but basically I just want to ask if, when choosing the p and q primes that, when multiplied, become the modulus for an RSA public key, is there a risk that ...
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### What is the Lord of the Ring(s): Side Channel Attack and What are the results

A recent Paper to appear on USENIX Security 2021 titled as Lord of the Ring(s): Side Channel Attacks on the CPU On-Chip Ring Interconnect Are Practical by Riccardo Paccagnella Licheng Luo Christopher ...
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### Example of breaking RSA with CRT [duplicate]

I understand that if the same message is sent to 3 people with $e=3$ that even with different public keys, the message can be decoded using the Chinese Remainder Theorem. I have tried to figure out ...
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### Why if i change some characters of a Public key on authorizedKeys the login still works

This question is similar to: [1] Why does my SSH private key still work after changing some bytes in the file? But in this case (on Windows) after editing the authorized_keys file and changing some ...
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### Combining ECC And RSA for a Web Based Chat system

I'm a building a Web application chat message system(Over TLS) and i would like to know if the following theory is correct. Sender I'm generating keyPairs using RSA and another KeyPairs using ECC. By ...
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### What is the NTRU parameter equivalent to security level 112, 128 and 192?

I came across this paper which mentions this table, which states that NTRU 347 is equivalent to 112 bit security level However, in this paper, Choosing parameters for NTRU mentions that NTRU-401 is ...
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### Factoring Anderson's RSA backdoor

In 1993, Anderson [1] proposed a backdoor to the RSA key generation algorithm. This backdoor requires that a backdoor key (prime) $A$ be implanted within the key generation portion of the RSA ...
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### Reveal a plaintext with 3 encryptions of Textbook RSA

Assume we using Textbook RSA encryption with the public key $(N,3)$. How can I learn message $m$ if I have the encryptions of $m,m+1,m+2$ in an efficient way? I'm studying for a test and it's a ...
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### Guarding against vulnerabilities for a digital signature service (RSA )

Lets's say I have a cipher-module / cryptography-service that signs a hash of some unknown payload. What are the possible attacks that I would need to guard against in this context (primarily assuming ...
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### Can an altered RSA private key still work as the original?

I am interested in understanding public-key encryption using RSA. On the Khan Academy website, I noticed an anomaly when testing out the tutorial. I created the following public/private keys: ...
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### IV in RSA Encrypted Private Key

I have been provided an RSA encrypted private key which was generated in NodeJS (crypto) using the following: ...
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### Why does PGP still use the Fermat primality test? What if it hits one of the Carmichael numbers？

Since the Fermat primality test is not very reliable, most applications use it for pretesting only. Wikipedia says that PGP still uses it: Another well known program that relies only on the Fermat ...
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### Generating a SHA256 pkcs1v1.5 Blind RSA Signature using Chaum's Blind Signature Scheme

I am a noob to cryptography in the sense that I have very less understanding as to how RSA encryption schemes work in practice. However I do understand the theoretical foundations of RSA cryptography ...
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### Using a RSA signature to confirm the sender of a physical letter?

(1) Alice wants to send Bob a physical letter. (2) Alice also wants Bob to be confident that she sent the letter and not an imposter. (3) Alice is confident that a potential imposter will not be able ...
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### Is PyCryptodome's export_key with passphrase secure?

When exporting a private key with PyCryptodome, DER format, PKCS#8 and a suitably strong passphrase, is the resulting exported key secure enough to place somewhere that you would not normally want ...
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### Best model for client software encryption / decryption

I would like to develop a small solution (c#) that must secure data exchange with an untrusted server. The model is that this software will run on a Windows client then Encrypt data before pushing it ...
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### How to handle modular arithmetic with regard to two's-complement negative numbers?

The reason for asking, is that this occurs in real life with CRT calculation of RSA decryption/signing. In CRT RSA, there's the need to calculate subtraction, and it's known negative numbers could ...
As explained in this answer, if one knows the trapdoor (factorization of modulus $N$) in an RSA accumulator, one can generate fake membership proofs. Does the same apply to non-membership proofs? More ...