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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Cycle attack on RSA
I originally posted this question in the mathematics section, you can see it here.
Let $p$ and $q$ be large primes, $n=pq$ and $e : 0<e<\phi(n), \space gcd(e, \phi(n))=1$ the public encyption ...
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Including a “purpose” designation in a digital signature
A signature of some data can mean many different things, such as: This is a message I sent, this is a certificate I validated,... So I was surprised that common signing schemes don't include a ...
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1answer
561 views
RSA: If n=35, show that e will equal d
Show that if $n = 35$ is used as an RSA modulus then the encryption exponent $e$
always equals the decryption exponent $d$?
What I have so far:
$n = 35$
Therefore $p = 5$ and $q = 7$ or vice versa, ...
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2answers
408 views
Proof of security for RSA signatures
I am new to here, I was having some problems with a problem I am working on:
"For each of the following variants of the definition of security for signatures, state whether textbook RSA is secure ...
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1answer
440 views
Why is ElGamal considered non-deterministic?
One difference between RSA and ElGamal is that ElGamal isn't necessarily deterministic (while RSA is).
What makes it non-deterministic? Is this advantageous to security? How else does this property ...
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1answer
364 views
What does SSL use? RSA? El-Gamal? Elliptic curves?
I'm not sure what SSL uses to share the symmetric key to both end users, i.e. at the beginning of the communication. Is it RSA? Or El-Gamal? Or something else?
Thanks!
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Definition of Textbook RSA
What is the definition of Textbook RSA?
What are some of the properties of textbook RSA?
How does it differ from other RSAs?
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How do I solve this RSA instance for m?
How we can solve this equation and get the value of M?
$$8 = M^{13} \mod 33$$
not a computer program, but a mathematical operation.
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1answer
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How are trapdoor functions developed/found and where can I find existing ones?
Trapdoor functions are a fundamental part of public key cryptography. An example of the most common trapdoor is
Prime Factorization, used in cryptosystems such as RSA
How are these trapdoor ...
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1answer
438 views
RSA-based authentication and key-agreement protocol
An authentication and key-agreement protocol between devices shall mutually demonstrate their identity, and establish a shared random secret $R$ suitable for securing later communications.
To that ...
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1answer
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Demonstrating the insecurity of an RSA signature encoding scheme
I'm working on problem 12.4 from Katz-Lindell. The problem is as follows:
Given a public encoding function $\newcommand{\enc}{\operatorname{enc}}\enc$ and
a textbook RSA signature scheme where ...
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2answers
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Cracking plain RSA without private key
I was wondering whether plain RSA encryption can be cracked given:
The public key
A plaintext of a known cipher text(s).
In other words the decrypted message from an encrypted one (but without ...
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1answer
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What is the property of RSA where N=e?
In RSA, suppose we know that $e=N$ and we are given the value of $e$.
($N = p\cdot q$ for some large primes $p$ and $q$; $\gcd(e, \varphi(N) = 1)$
Can we calculate $d$ ($d = e^{-1} \mod ...
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Is it reasonable to assure that p-1 and q-1 aren't smooth?
I came across the requirement that, in RSA, $p-1$ and $q-1$ shouldn't be smooth, shouldn't consist of lots of small factors. Therefore my question:
How complicated is it to check whether $p-1$ is ...
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2answers
411 views
Is a RSA-signature of some identifying data a safe way to implement a license key?
I have this idea of implementing a license key:
After the user downloads the program, he connects to a website and sends his Windows product ID.
The website, then, sends this back to him with a ...
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1answer
674 views
RSA-PSS salt size
One of the inputs of RSA-PSS signing and verification is the salt size. According to PKCS#1, you must know the salt size before the verfication is carried out. However, this makes interoperability ...
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Are there practical upper limits of RSA key lengths?
Suppose one wanted to use RSA encryption for the sole purpose of sending key bits for use in symmetric crypto systems, a dedicated key exchange system so to speak.
And say you didn't think that the ...
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Is it feasible to build an index of prime factors?
Would it be possible to break an RSA key, in for example 1 week of time, if the cracker have already spent X number of years building an index of primes by performing every permutation of existing ...
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What is the likely cause when this happens in RSA Algorithm
In using the RSA Algo , if a small number of repeated encodings give back the plain text , what is the likely cause ( Text book question of Chapter 9 ,Crypto and Network Security , William Stallings ...
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2answers
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In RSA, do I calculate d from e or e from d?
In the original paper introducing RSA, it is implied that one should first choose $d$ and then calulate $e$ from $p$, $q$, and $d$. However, I have found in other places (such as the wikipedia article ...
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1answer
230 views
What algorithm does PGP use to encrypt email?
I know it uses RSA/DSA to create keys, but does it use that same algorithm for the actual cipher?
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How can I generate large prime numbers for RSA?
What is the currently industry-standard algorithm used to generate large prime numbers to be used in RSA encryption?
I'm aware that I can find any number of articles on the Internet that explain how ...
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1answer
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is it possible to spoof an identity cert modulus
I was looking at foaf+ssl http://www.w3.org/wiki/Foaf+ssl and wondering if its possible to spoof the modulus of the browser cert so that the foaf and browser cert modulus match
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Why has the RSA factoring challenge been withdrawn?
Wikipedia states that RSA challenge has been withdrawn.
Does it mean that an efficient factoring algorithm is "just around the corner"?
or are there some other reasons?
If the challenge was still ...
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1answer
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How do other, non-RSA algorithms, compare to the PKCS #1 standard?
Arguably the PKCS suite of standards have a profit-oriented bias as they are promoted by RSA and promote their algorithms over others in the form of RFCs and other means.
I'm considering the ...
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1answer
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When is an asymmetric scheme considered broken?
Does the following quote imply that valid encrypted data can be created and decrypted by someone other than the owner of a private key:
An asymmetric encryption scheme is considered to be broken ...
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2answers
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How to calculate the time it'll take to crack RSA or DH?
Sometimes the easiest way to describe security of a type of cryptography is to say that "the time it takes to solve for an x-bit key would be y years". How would one go about doing such a calculation ...
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Is it possible to create an asymmetric cryptosystem where the private keys are not easily verifiable as such?
Plaintext that consists of an RSA key is easily recognizable as such, because it satisfies certain mathematical properties, in particular (See the answer for Why can an encrypted private key be brute ...
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Preventing message replay with RSA
I am using RSA to encrypt some data but I would like to eliminate the possibility of message replay. By message replay I mean sending a valid message multiple times to the original recipient. It is ...
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2answers
504 views
Using an RSA private key simultanously as an AES encryption key to generate random numbers?
Currently I'm implementing a PRNG for an embedded system. Using the RFC 4086 I've decided to use the X9.17 - to be more specific the succesor X9.31- standard to implement my PRNG. X9.17 uses DES, but ...
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Are any of the major asymmetric ciphers distinguishable (EG, RSA, ECC) ?
Related to this question.
Given ciphertexts generated by any of the major asymmetric ciphers (RSA, ElGamal, ECC, etc..) can these ciphertexts be distinguished from random noise? Justify why, why ...
