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.
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Generate a per data shared secret vs per session
I have read about SSL that they persist the shared-secret for the entire session. However, someone in stackoverflow suggested a way of generating a shared secret for each data to send and then send ...
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1answer
51 views
Why is lcm(n) used now instead of $\varphi(n)$ in RSA? [duplicate]
I know that lcm(n) or Carmichael's totient function $\lambda(n)$ is now used instead of $\varphi(n)$ or Euler's totient function to generate the public key in RSA encryption? Why is this so? Are there ...
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1answer
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Prime numbers in RSA encryption [duplicate]
I'm studying how the selection of prime numbers in RSA encryption may affect the security of the encryption in regards to the public key.
Essentially, are there any specific types of prime numbers ...
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2answers
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How exactly are GPG keys (and prime numbers inside of GPG) mathematically related?
I know that the keys are somehow mathematically related, and I know that they're somehow generated via prime numbers, but how exactly are they related? I realize that it'd probably be best for me to ...
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2answers
78 views
How does AWS Secret key and access key work
Those keys are too short to be public/private RSA keys. What are they? How does it use them to authenticate the client?
My guess is:
AWS access key ID is a form of unique user/account identifier
AWS ...
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1answer
45 views
Value of $\varphi(n)$ and $\lambda(n)$
Is it true that $\varphi(n)$ is generally larger than $\lambda(n)$ for the same $n$? If so, can anyone give me a proof?
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1answer
60 views
Do Carmichael's and Euler's totient functions in RSA generate the same keys?
Starting with the same primes $p$ and $q$ to generate $n=pq$, will Carmichael's totient function and Euler's totient function give the same public key ($e,n$) and private key ($d,n$) in RSA encryption?...
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Time complexity of Carmichael's totient function [duplicate]
I'm studying the efficiency of Euler's totient function and Carmichael's totient function used in RSA encryption.
I do understand that Euler's totient function has several different time complexities ...
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1answer
59 views
Will publishing two or more public keys of the same RSA private key cause a security risk?
I want to make an end-to-end messaging platform where everyone is identified with a unique random private key. Everyone uses other peers' public keys to identify and send encrypted messages and verify ...
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2answers
468 views
Computational complexity of RSA
What's the computational complexity or RSA? One can assume it's O(prime length^2) it you consider multiplication by column, but speed tests slightly differ on slow operations with private key and ...
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2answers
868 views
How does RSA public and private key structure look like?
So I was reading this wiki about the RSA algorithm and I read this article to understand it better. My goal was to create a simple program that would generate private and public keys. I got to the ...
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2answers
11k views
Using the same RSA keypair to sign and encrypt
The RSA signature operation is basically the same as encrypting with the private key. In particular, both operations use the same kind of keys.
Is it safe to use the same RSA keypair both for ...
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4answers
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Choosing which is public vs private key
When I calculate two RSA keys, what if anything, would make any difference which I call the public vs which I call the private key?
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1answer
736 views
Main purpose for Carmichael's Function in RSA
I'm trying to understand the RSA cryptosystem, these are the steps:
Generate two large different prime numbers $p$ and $q$.
Calculate modulus $n$ ($n=pq$)
Calculate: $λ(n) = \operatorname{lcm}(λ(p), ...
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1answer
60 views
Picking 'e' for RSA encryption
What is the reason behind picking either $3$ or $2^{16}+1$ for generating the public key in RSA?
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2answers
725 views
Is RSA inspired by Diffie Hellman?
I read a bit of A Method for Obtaining Digital Signatures and Public-Key Cryptosystems that introduced RSA in 1977, and, while learning the steps in RSA a few days ago, I noticed that they are similar ...
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Can modular operation used along with bit shif for cryptography? [closed]
Let a be input value, k1 and k2 be two keys.
Then
X=(a+k1) mod m;
X=(x<<4);
Y=x^k2;
Can i decrypt back? Because i am not getting exact answer while ...
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1answer
44 views
Probabilistic padding to avoid Håstad’s Broadcast Attack
Can someone explain why probabilistic padding like OAEP is particularly useful for avoiding Håstad’s Broadcast Attack? I don't really get the reason why.
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18 views
PDP schemes parameter generation
For the PDP scheme, I need to generate the following parameter:
g is a generator of Q (Q is the set of quadratic residues modulo N (N = pq is the RSA modulus)
What algorithm can be used to generate ...
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0answers
6 views
Can we write both encrypted text and plain text to the same file? [migrated]
We have a requirement from customer to write payment transaction information to a text file. Of many lines of data per transaction, only one line contains cardholder information, which needs ...
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2answers
6k views
RSA with modulus product of many primes
I would like to ask what happens if we build an RSA system with modulus a product of more than 2 primes, for example let $n=p_{1}p_{2}...p_{L}$. I know only the classical RSA system with $n=pq$ with $...
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1answer
59 views
How to calculate e if we know n,p,q,m,c? [duplicate]
If we know n, p, q, and we have an encrypt oracle, which means we can input any plaintext and we'll get its ciphertext, and here p is smooth, which means the factors of p-1 are very small, is that ...
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1answer
114 views
Is OAEP needed when encrypting a session (random) key using RSA?
My question is two parts:
when encrypting a session key which is used to encrypt bulk data using a block cipher for example, is padding with OAEP really needed [i'm assuming the key is generated ...
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3answers
530 views
Why does OpenSSL differentiate between PSS and non-PSS for private key generation?
RSA-PSS private keys
The following command will generate an RSA-PSS private key:
...
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1answer
83 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 ...
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0answers
25 views
How to get the key data from the pkcs#8 format? [closed]
Being newbie to crypto, I understood that RSA keys are shared are pairs $(e,n)$ or $(d,n)$. But when I was given a doc with keys, they were in PKCS#8 format.
How to get the keys out of this format?
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2answers
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Which attacks are possible against raw/textbook RSA?
The PKCS#1 standard defines multiple padding schemes for signature generation/verification (EMSA-PSS and EMSA-PKCS1-v1_5), and encryption/decryption (EME-OAEP and the less safe EME-PKCS1-v1_5).
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1answer
35 views
How to prevent Public Key from being replaced entirely?
I am using RSA to sign my license file using Microsoft CNG API. I am signing the license file and sending the file with the <...
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2answers
530 views
Guidelines for cryptographic key generation
I was wondering whether you know can point me to some general (basic) principles/guidelines one should follow for generating cryptographic keys? I have looked at NIST 800-133, but was hoping for some ...
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1answer
26 views
I have created values for rsa encryption but it dosent always work [duplicate]
i am suing 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 the value ...
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0answers
9 views
Get modulus of ssh-rsa public key? [migrated]
I'm trying to verify a JWT on client side with Auth0's library idtoken-verifier and am getting thrown an error when checking modulus and exponent of my public key (https://github.com/auth0/idtoken-...
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2answers
93 views
How do I calculate e, d and N based on raw and encrypted message in RSA?
I've got raw and encrypted message, which contains only numbers. For example:
Message: 32016550980634121428089400169, encrypted: 35682226122303060179704449482
I'...
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1answer
64 views
Why is the strength of an Elliptic Curve Cryptography (ECC) half the size of the prime field size?
I've looked around and couldn't find a direct answer. As a general rule, I've read from various sources (here here, and here) that the strength of an elliptical curve key is half of the size of the ...
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0answers
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Difference between JWE encryption algorithm RSAES-PKCS1-v1_5 and RSAES OAEP [duplicate]
In the specifications of JWE (RFC7516) they specify the values for (asymmetrically) encrypting the symmetric key. In RFC7518 in section 4.1 they list the options, of which two are relevant for my case
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1answer
57 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.
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finding private key for RSA
for RSA $N=pq$, $c = m^e \bmod N$
if $m^{12345}= 1 \bmod N$ is given, how to find RSA private key $d$ and message $m$.
Note: $N,d,\phi$ are unknown. $e$ is publicly available.
I think we can take $...
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1answer
283 views
How to choose the integer m in the general number field sieve (GNFS)?
Given an integer you want to factor $N$, GNFS starts by selecting a monic irreducible polynomial $f \in \mathbb{Z}[X]$ and an integer $m$ such that $f(m) \equiv 0 \text{ mod } N$. In practice, if $m$ ...
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1answer
376 views
Using One Time Pad and RSA compared to using only One-time Pad
Here I implemented One Time Pad first for only one time and then I used RSA algorithm to encrypt the message.
For RSA algorithm, I pick p = 2143 and q = 3257 value which does not share any common ...
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2answers
1k views
How can a message encrypted with the public key be decrypted with the private key?
I've been reading about encryption and have a basic understanding of the concept. What I don't understand, however, is how a calculation with one key can result in a number that, through calculation ...
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0answers
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is there any good implementation to the RSA in arduino ? c language [migrated]
I need a good implementation to the RSA algorithm that works on Arduino mega with key size 1024. the code will run on Arduino ide.
the project idea simply is an android app send an encrypted message ...
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3answers
13k views
Is RSASSA-PKCS1-v1_5 a good signature scheme for new systems?
Is RSASSA-PKCS1-v1_5 a good signature scheme to recommend that people use in new systems? Is it believed to be secure and represent the state-of-the-art in RSA-based signatures?
I understand that ...
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2answers
81 views
RSA padding: risk of using constants
Assume I want to make my RSA secure because I heard that textbook RSA, especially in conjunction with low exponents, is very risky. I decide to limit my message length to 100 and subsequently ...
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2answers
594 views
Using Lattice-based cryptography for TLS\SSL
Given the general benefits of Lattice-based cryptography, such as:
Post quantum Security
Security from worst case scenario
Efficiency
What could the outlook of shifting from RSA \ ECC-based ...
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3answers
299 views
Why does BitLocker not use RSA?
If understand correctly from this post and the Wikipedia page for BitLocker and TPM, by default, BitLocker uses symmetric cryptography like AES. However, TPM is capable of performing RSA encryption.
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3answers
258 views
Can Shor's algorithm factor multi-prime numbers?
I know that Shor's algorithm can factor semi-primes ($N = p \times q \space, \{p, \space q \in \Bbb{P} \space \vert \space p, \space q \gt 0 \} $).
Assuming that all prime numbers are so large that ...
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1answer
71 views
RSA calculate public exponent
Suppose I have two messages $m_1$ and $m_2$ as well as $c_1$ and $n$. It's standard RSA so $c_1 = m_1^e \ mod \ n$, $c_2 = m_2^e \ mod \ n$. Further assume the only information we have about e is that ...
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1answer
507 views
The 9 lives of Bleichenbacher's CAT, it puts another scratch again
Bleichenbacher demonstrated a padding oracle attack against RSA implementations that follow the PKCS #1 v1.5. Through the years, there are various mitigation techniques developed as OAEP and limiting ...
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1answer
68 views
Discrete logarithm with exponentiation oracle
Suppose $(n, d)$ is an RSA private keypair. We know the public key only (wlog suppose it's $(n, 2^{16}+1)$ and we are given oracle $E$, decryption oracle for $(n, d)$. Is there any efficient algorithm ...
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81 views
RSA low exponent with padded plain-text
Considering a case, when modulus is large and hard to factor, exponent e=3 and there is a cipher-text which is created by padding plain-text with ...
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2answers
294 views
RSA find public exponent
Suppose I have an encryption oracle which can encrypt $m^e \mod n$ for any $m$. I know $n$ and I know $\varphi(n)$. However the public exponent $e$ is secret. Is it possible to figure out it's value ...
