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
501 views
Common Modulus Attack in a Lucas Group
I'm trying to decrypt a message that is encrypted using a LUC encryption scheme and running into roadblocks. I know that with RSA if Alice and Bob use the same public modulus but different encryption ...
2
votes
1answer
227 views
Attacks on the RSA Cryptosystem
I was reading some articles about attacks on RSA system and I wonder about some generalization of the following theorem.
Theorem (Coppersmith).
Let $N=pq$ be an $n$-bit RSA modulus, where
...
8
votes
0answers
135 views
What changed in PKCS#1 v2.2, and why?
PKCS#1 is one of the most used (de-facto) standard for real-world use of RSA.
That's for good reasons: PKCS#1 is well thought, versatile, understandable, has been relatively stable for over two ...
5
votes
0answers
144 views
Prove that textbook RSA is susceptible to a chosen ciphertext attack
Given a ciphertext $y$, describe how to choose a ciphertext $\hat{y} \neq y$, such that knowledge of the plaintext $\hat{x}=d_K(\hat{y})$ allows $x=d_k(y)$ to be computed.
So I use the fact that the ...
2
votes
0answers
101 views
Ring Signature - paper/code difference in trying to solve inverse trap door function?
there is a paper on ring signatures and a python implementation of it here.
The Step 4 in the paper describes $y_s = v =C_k,_v(y_1, y_2, ... y_r)$ for all $1 \leq i \leq r$ where $i \neq s$. The ...
2
votes
0answers
113 views
RSA reencryption scheme
Is there such an algorithm that would allow to upgrade the encryption of a RSA-encrypted message without revealing the plaintext to the untrusted user?
Basically, such an algorithm would probably be ...
1
vote
0answers
27 views
Generating Polynomials for the MPQS
I'm going to try and eventually factor RSA-100, but my current QS needs a lot of improvement, so I'm going to try and switch over to the MPQS.
I'm a bit confused as to how the MPQS works, which is ...
0
votes
0answers
60 views
Method and explanation for calculating difference in speed between DES and RSA
Our assignment asks us to convert an RSA speed in bytes per second to a DES speed in bytes per second. Our professor's treatment of this ("RSA is 100 times slower than DES") seems insufficient. Could ...
0
votes
0answers
37 views
Is it possible to determine the group order by knowing the “public” and “private” key exponents in an RSA group?
I have an RSA group with modulus $n = p \cdot q$, two safe primes $p=2p'+1$ and $q=2q'+1$ and the "public" and "private" key exponents $d$ and $e$. $\phi(n) = 4p'q'$ is the order of the RSA group. If ...
0
votes
0answers
71 views
Strong RSA problem in $\mathbb Z^*_{n^2}$
Comparing to this question, assume $C, M \in \mathbb Z^*_{n^2}$, $e \ge 3$, is it hard to compute $M$ that satisfies $C=M^e \mod n^2$ when $C$ and $(n, e)$ are given?
0
votes
0answers
82 views
RSA and One Time Password (OTP) service
What is the expert cryptographic opinion on the following?
Assume that there is a web server and a client on web page.
User on the Client calls an OTP web service on the server which
a) creates a ...
0
votes
0answers
77 views
Factorize RSA knowing several N and E
I did a CRT challenge yesterday and there`s one problem I was unable to solve, probably due to my lack of understanding advanced crypto math.
It`s about RSA. There are ten given pairs of N and E ...
