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.

3
votes
1answer
1k views

In which public key encryption algorithms are the private and public key not reversible?

The RSA public key encryption system has the characteristic that the public key and the private key can be reversed. That is, information encrypted with the public key can be decrypted with the ...
0
votes
0answers
42 views

Encryption/Decryption on multiple users using RSA?

Supposing I have Alice that is the RA, Bob (who is a user) and Kate (who is also a user). For now I use RSA. Alice sends a message to Bob. Alice also sends a message to Kate. Bob and Kate exchange ...
0
votes
0answers
28 views

Alternate to distributing master key to every user in circle of trust

I am designing an end-to-end encrypted file storage system where only the user should be able to access their own data. The best I could come up with is a system designed around a master key that is ...
9
votes
4answers
6k views

Why do we need Euler's totient function $\varphi(N)$ in RSA?

After we calculated $N = p * q$, we calculate $\varphi(N)$ and use it later to determine $e$ (PR) and $d$ (PU). But why? For decryption and encryption we only use $N$ and don't need $\varphi(N)$. So ...
2
votes
1answer
63 views

Is there an equivalent to an RSA UFO in lattice-based cryptography?

So there's this concept within the realm of RSA cryptography called an RSA UFO. It is an extremely important function in the context of cryptocurrency. When starting up a cryptocurrency the creator(s) ...
0
votes
0answers
31 views

What is the “most secure” way to public/private encrypt a 64 bit value? [closed]

I want to encrypt a 64-bit value using a private key. The data size is limited to 64-bit, so the encrypted data must also not exceed the 64-bit limit. The receiver of the encrypted value should be ...
0
votes
0answers
18 views

PBKDF (password) inputs [closed]

If I want site engineer to export data having it encrypted and should be able to read as well as upload it to a server later in case of no internet situation. Is PBKDF (password) should be a good ...
1
vote
1answer
64 views

What encryption shoud I use for single char encryption?

I'm very new to encryption and I wanted to know if it is secure or just possible to use encryption on single chars. I did some research, but nothing to clear and i'm a bit confused. The modes I think ...
1
vote
1answer
55 views

Can the original data be extracted from an RSA private key signed message

I'm working on a system that the main objective is to verify the message was written by the right person, but it would also be desirable if the message can't be understood by anyone sniffing it. It ...
-4
votes
2answers
82 views

Prime number size and RSA decryption

Is there a former proof for why larger prime numbers make RSA securer? Maybe a theorem to show that it takes much more time to find out the private key if primes are larger?
-4
votes
0answers
35 views

I am participating on an international competition, my topic is Cryptography: The RSA Algorithm [closed]

I am participating on an international video science competition. My topic is Cryptography: The RSA Algorithm. I would be more than happy to receive your feedback! Please take a look at it! It will ...
3
votes
3answers
207 views

RSA - What's to stop someone from using the same ciphertext to mimic private key holder?

I've recently looked into fundamentals of RSA and think I understand how it works. However, there's one basic problem I can't seem to figure out. If someone received ciphertext for a given message, ...
-1
votes
0answers
26 views

CRT to decrypt RSA [closed]

How can the Chinese Remainder Theorem be used to decrypt RSA (or the public key) and find out the private key? If it is possible to do this with the CRT, then does the size of prime numbers used to ...
0
votes
1answer
41 views

What does it imply if in RSA pow(m, e, n) is same as the m

So, Let's assume we have n which is made up of 2 strong primes which cannot be factored & e which is textbook value of e ...
0
votes
0answers
30 views

RSA Digital Signature System is failing for larger Prime numbers [migrated]

I implemented RSA cryptosystem to create a simple digital signature system. It is for freeCodeCamp's upcoming Cryptography curriculum. The below program logs "Failure" when I use some bigger prime ...
0
votes
2answers
100 views

Why is prime number size important for RSA security?

RSA modulus is $N = pq$ where $p$ and $q$ are prime numbers. I read from somewhere that the time it takes to decrypt the RSA encryption increases exponentially as key length increases, which depends ...
7
votes
0answers
115 views

RSA factorization with special primes

Suppose that primes for RSA modulus are generated using formula: $P_i(x,y) = \operatorname{next\_prime}(x^{z_i}+y^{z_i}) = x^{z_i}+y^{z_i}+d_i$ where $x,y$ are unknown random numbers with size 128 ...
0
votes
1answer
40 views

Probabilistic verification of signature schemes like RSA?

I was wondering if there were any verification algorithm in the literature that enables a "probabilistic" verification of well-known signature schemes? For RSA signature verification for example, is ...
1
vote
1answer
43 views

I have created values for RSA encryption but it doesn't always work [duplicate]

I am using the values as follows: $(p, q, n, \phi(n), e, d) = (1033, 5039, 5205287, 5199216, 65537, 3784241)$ Yes, I have made sure $e$ and $\phi(n)$ are coprime. For example, if I were to encrypt ...
0
votes
1answer
76 views

Plain RSA with $3$ primes, find all integers $x$ so that $x$ is equal to $y$ when $y= e_K(x) = x^{b} \bmod n$

I'm using the notation from the book: Cryptography: Theory and Practice, Third Edition. I have a cryptosystem with the following information: $n = p_1 p_2 p_3$ and integer $x$ is encrypted using $y =...
2
votes
1answer
48 views

Brute forcing the value of m in RSA

I looked into the math behind RSA and seem to understand the basic encryption and decryption scheme. Let's say there are two parties, Alice and Bob, who wish to communicate and secure their ...
2
votes
1answer
26 views

consequences of using fixed values with OAEP

With DSA / ECDSA using a fixed $k$ means the private key can be trivially easily calculated from two different signatures. To remedy this RFC6979 Deterministic Usage of the Digital Signature Algorithm ...
2
votes
1answer
92 views

man-in-the-middle attack on text-book RSA PKE

I am attempting to solve the following problem: I know the following: 3 messages are being sent between Alice and Bob, all messages are encrypted with the known public key $(d,N)$: Alice sends ...
11
votes
1answer
195 views

Is this paper's technique for factoring RSA 2048 with noisy qubits realistic?

A paper titled How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits has just come out which proposes a technique to factor RSA keys with moduli up to 2048 bits with a design ...
3
votes
1answer
101 views

What makes lattice-based cryptography quantum-resistant?

As opposed to RSA or elliptic curve cryptography?
1
vote
1answer
69 views

How should I address message size limits in RSA encryption?

I am making an end-to-end encryption software program in Java using RSA. I am using BigIntegers and its number theory methods. (I know this is a very slow approach, but I just want to learn to the ...
0
votes
1answer
86 views

Could a quantum computer recover files from ransomware if the attacker doubly encrypted them with RSA-4096?

How would a quantum computer decrypt a file (or find the keys to such a file) if it were encrypted with standard RSA 4096 encryption, but encrypted two times with different keys? The keys are known by ...
0
votes
0answers
45 views

RSA attack with really big N? [duplicate]

N is a really big number,2466 digits in base 10,and e is 65537,I thought n might be factored,but it didn't work. N is such a big number and e is 65537,smaller than N,so how to attack it?
3
votes
1answer
155 views

Inclusion and Exclusion proofs in RSA accumulators

I am reading about RSA accumulators from this video and few other sources. I had a confusion whether the complete set is needed to construct a proof of inclusion/exclusion in an RSA accumulator or is ...
-3
votes
1answer
71 views

how to decrypt if p=q in RSA [duplicate]

p,q should be different,but if I let p = q,and encrypt the plaintext,then I can't decrypt it,so can decrypt it?
0
votes
0answers
42 views

How to calculate RSA public key by modulus unknown format and exponant value? [closed]

I'm trying to calculate the RSA public key by modulus value and exponent value. I got the values from an API by Apple. You can find the API here. The documentation for the API can be found here. ...
1
vote
1answer
69 views

RSA - Very big Modulus and Ciphertext

Is there a known weakness in RSA when the value of modulus (n) is very large? n = 2466 digits e = 65537 c = 2466 digits n cannot be factorized. I checked on ...
-1
votes
1answer
83 views

RSA encryption, Number theory [duplicate]

In RSA algorithm we have the value of $e$ & $d$ exponent and also one of the prime numbers. My question is how to produce another prime number that is not equal to the first one and the digit of a ...
-2
votes
1answer
34 views

Given a point $c$ in a field $Z_p$. Can we get another value $c^{'}$ such that $\left(c^{\prime}-c\right)$ is invertible in $Z_p$?

If we have a point in a field $c$. Can we get another value $c^{'}$ such that $\left(c^{\prime}-c\right)$ is invertible in $Z_p$ ?
2
votes
2answers
94 views

Asymmetric keys (e.g. RSA) must be so much longer than symmetric keys (e.g. AES). Why? [duplicate]

I have been reading that RSA has to do with math (prime numbers), while symmetric key encryption deals with blocks of data and modifying the blocks with replacements and remappings, but I still don't ...
1
vote
2answers
53 views

Efficient attack on RSA with known padding scheme and public key

I am having some trouble with an assignment problem. I hope I can get some guidance here. The question provides us with a public key, $N$ and the padding scheme. This is the padding scheme "Assume ...
0
votes
1answer
64 views

How you find the unpadded short plaintext using RSA?

I am currently trying to understand how you find the unpadded short plaintext when you are using RSA. Please help with explaining the process and so I can understand this topic more.
2
votes
1answer
40 views

Does the multiplicative property apply to modern, non-text book RSA?

I'm aware of the multiplicative property of the textbook RSA and how it can be used to get a signature from a CA without having the CA directly signing it. My question is - can this apply to the real ...
5
votes
0answers
36 views

Finding the period of a function with a single output qubit - impact on RSA

In this paper,May and Schlieper claim that one can find the period of a function $f()$ by embedding $h \circ f = h(f(x))$ for input $x$. This would have the immediate consequence of reducing the ...
-1
votes
0answers
24 views

RSA - Deterministic Encryption vulnerabilities [duplicate]

Which are the vulnerabilities of RSA algorithm due to the fact that is a deterministic encryption method?
1
vote
1answer
77 views

Using Yubikey to store PIN protected secret for disk encryption

I want to store a secret on Yubikey and used it for the disk encryption. The crucial is, I want it to be PIN protected. There are a limited number of PIN tries, and after three attempts the Yubikey ...
1
vote
0answers
63 views

RSA vs. Super Computer vs. Quantum Computer

I know that RSA is known to be secure in the current landscape of computing, and I know that RSA is known to be broken in the world of quantum computing and cryptography. I have two questions, can ...
0
votes
0answers
6 views

Can use openssl instead of Python RSA and Base64 algorithms? [migrated]

Can use the openssl command to implement equivalent functionality with Python RSA and Base64 algorithms? For example, the RSA public key and the password to be encrypted are known. The Python ...
8
votes
1answer
3k views

How long does it take to crack RSA 1024 with a PC?

Using an Intel Core i5 CPU, how long does it take to crack RSA using a key size of 1024 bit (generated using a secure key pair generation function)? Suppose for instance that we have thousands of ...
1
vote
0answers
29 views

How to calculate RSA group signatures

RSA group/ring signatures, how are they calculated?
2
votes
2answers
57 views

Preferred SHA-2 hash algorithm for MGF1 in RSA

Does it make any difference to the security and efficiency if we use SHA-256 or SHA-512 for the Mask Generation Function MGF1 that generates the masking / padding within the OAEP encryption scheme and ...
17
votes
2answers
33k views

What's the difference between RSA and Diffie-Hellman? [duplicate]

I've been reading on a lot of websites that same thing: RSA is for communication using the public and private key for both the server and client, where Diffie-Hellman is just for exchanging the same ...
1
vote
0answers
54 views

RSA How to find the exponent ($e$) of the Public key with the values $p$ $q$ and an example are given

I'm wondering if it's possible to find the public exponent ($e$) with an example and the (rather small) values of $p$ and $q$ given. Currently the only option I found is bruteforcing this value, but ...
0
votes
1answer
56 views

RSA and possible range of $\phi(n)$

If $n = p_1 p_2$ for primes $p_1 \ne p_2$, $\phi(n)$ is $\phi(p_1)\cdot\phi(p_2)$. Does that mean that the possible range of $\phi(n)$ is somewhat narrow, that $(p_1-1) \cdot (p_2-1)$ (that is, $\phi(...
6
votes
1answer
7k views

Should I be using PKCS1 v1.5 or PSS for RSA signatures?

I am implementing an application where a user needs to sign some data that they have created, store it in an untrusted place, then later retrieve that data and verify it is still authentic before ...