Tagged Questions
0
votes
2answers
110 views
Physical Level Encryption
What types of algorithms that are capable of signing a message are out there that run on a physical level, e.g. lacking the infrastructure of a standard PC, no memory, processor or motherboard in the ...
-1
votes
1answer
84 views
What length should the padding be when encrypting or signing with RSA?
Does it matter what length the padding is? If so - what length should it be?
(Another point: Should it be random?)
0
votes
1answer
92 views
RSA - Ecrypting the same data with the same public key = same ciphertext?
If an adversary knows my public key and guesses what was my plaintext, can he test for it somehow?
The most obvious way is encrypting the guessed plaintext with my public key and the same parameters ...
3
votes
1answer
138 views
Secure encrypt-then-sign with RSA
I understand that when you want to encrypt and sign data with RSA the generally recommended approach is sign-then-encrypt.
However, I have encrypted data that I need to sign, to prove the author of ...
3
votes
1answer
82 views
implementing long term archive encryption
Let's say I want to create private archives for the long term (e.g. more than 30 ). The archives' sizes could be anywhere from 1 GB to 30 GB. As far as I understand I could go down two ways:
The ...
-4
votes
0answers
63 views
RSA Encryption Sckeme [closed]
Can anyone help me with this question?
A and B want to exchange encrypted messages; specifically, B wants to send a message M
written in binary format to A, which needs to be encrypted. They agree on ...
3
votes
1answer
112 views
Combining AEAD with RSA
'Hybrid' encryption, where we combine symmetric encryption with public-key cryptography, is pretty 'tried and tested'.
To summarise, we generate a symmetric key and encrypt it using RSA. We would ...
2
votes
2answers
134 views
How can mega store my login details and still be secure?
I understand how Mega's encryption works. For a quick summary of all those in the future looking for an answer on this... here is how it works:
Upon first signing up for an account you make a ...
0
votes
1answer
46 views
Solving congruences using PARI
I'm having trouble finding info in the docs about how to solve a system of congruences. The closest I can find is 'matsolvemod' in here: ...
2
votes
1answer
187 views
Low Public Exponent Attack for RSA
I'm having trouble understanding the algorithm for finding the original message $m$, when there is a small public exponent. Here is the example I'm trying to follow (you can also read it in the 'Low ...
4
votes
1answer
136 views
Question about why RSA is hard to attack
I think I understand why RSA is hard to attack but I'd like to get clarification if I actually do.
Assume there are two people, Alice and Bob, who are attempting to communicate privately but that we ...
1
vote
1answer
419 views
How do I derive the time complexity of encryption and decryption based on modular arithmetic?
I want to calculate the time complexity of two encryption and decryption algorithms.
The first one (RSA-like) has the encryption
$$ C := M^e \bmod N $$
and decryption
$$ M_P := C^d \bmod N. $$
...
0
votes
0answers
47 views
How compute encrypt and decrypt runtime for agorithm [closed]
I programming RSA algorithm is the following two function in java language in my thesis
...
2
votes
1answer
257 views
What happens if an RSA key pair has identical public and private exponents?
Rather, is it possible for big prime numbers?
Classroom examples usually involve smaller primes, so for example if you are given a prime number pair $p = 3$, $q = 13$ you would get $n = 39$ and $e = ...
2
votes
1answer
75 views
Individual bits of Textbook RSA
This question relates to the underlying RSA assumption. Forgetting about the fact that Textbook RSA is deterministic, I am curious about the assumed strength of the RSA problem.
Does RSA hide all ...
2
votes
1answer
228 views
How much extra information is in an RSA public key?
I'm trying to calculate the size of an RSA public key in Ruby. I've retrieved the key in PEM format, and once I've decoded the base64 part from the PEM format, I get the size in bytes. What I find is ...
4
votes
1answer
144 views
In RSA encryption, does the value of e need to be random?
I am a novice programmer and am just finishing up an RSA encryption program that I am writing for practice. Currently I have the program generate a relatively small random value for the public key e. ...
1
vote
2answers
118 views
RSA keys finding when messages are known
I have this situation, where, in a game, people send messages to each other (game moves etc...) These messages need to be encrypted, and should only be readable by the destination person. I am using ...
2
votes
1answer
155 views
What is the strength of unpadded RSA?
I would like to use unpadded RSA for homomorphic encryption in a toy P2P game, for things like fair coin flips and shuffling.
How many bits of security does unpadded RSA have, in relation to its key ...
8
votes
2answers
471 views
Why RSA can't handle numbers above 76?
I'm going to encrypt the characters Zhu, and decrypt them using RSA. I'm using the public key $\{e, n\}$ and private key $\{d, n\}$. The values of $e$, $d$ and $p$ ...
1
vote
2answers
760 views
Secure private key storage
I'm developing application in Java that has to store RSA keys in software for foreseeable future (that is, at least 10 years).
The two most common standards of storing private keys are PKCS12 and JKS ...
3
votes
2answers
135 views
Textbook RSA to Realworld RSA
Is there a paper or link where it explains , how the plain vanilla Textbook RSA is actually implemented in practice with all the padding and stuff ?
basically i want to know the intricacies of ...
0
votes
1answer
118 views
RSA Signature - Multiple Use Weakness
I cite from Fundamentals of Computer Security (Chapter 7 on Digital Signature, Paragraph 7.3 on RSA Signatures, page 289):
Multiple uses of the RSA Signature scheme tend to weaken it. The way out ...
6
votes
2answers
2k views
What's the fundamental difference between Diffie-Hellman and RSA?
What is the difference in the purpose of DH and RSA? Aren't they both public-key encryption?
2
votes
2answers
192 views
Is RSA in a ECB-like-mode safe for bulk encryption?
Let's say I would like to communicate with my friend using asymmetric/public-key encryption, e.g. RSA.
(Note: I do realize that in practice this is done through an intermediate symmetric key, but ...
3
votes
1answer
124 views
Safely use CryptSignAndEncryptMessage?
I am developing an application that sends messages which I want to encrypt and sign. The CryptoApi offers a function called CryptSignAndEncryptMessage.
The description says, what this function ...
2
votes
1answer
430 views
How to sign a message using RSA?
Assuming I already have a D, P, Q, etc of an RSA key: How do I now sign a message? If it matters – the message is around 100 bits.
I don't know much about cryptography, but I can get these numbers ...
3
votes
2answers
290 views
Can RSA encryption produce collisions?
In RSA, a message is encrypted by $m^e \pmod N$. $N$ is the modulus, $m$ is the message and $e$ is the public exponent. (I know that $m$ should not be greater than $N$.)
My question is, can $m^e$ be ...
1
vote
2answers
175 views
One-way function and factoring
I am confused about the hardness of the one-way function behind cryptography -- if someone could factor the large number produced back into two primes quickly then the one-way function would be ...
3
votes
3answers
4k views
RSA encryption with private key and decryption with a public key
Does the encryption with a private key and decryption with a public key works in RSA? Is it done when we use RSA for sender authentication ?
Thanks.
4
votes
1answer
185 views
Why does RSA give better security on longer messages?
I am trying to understand the notion of RSA security.
Choosing a public exponent where $e = 3$ facilitates the calculations, considering that it is secure if the plaintext or message is long.
If the ...
6
votes
3answers
1k views
Why RSA encryption key is based on modulo(phi(n)) rather than modulo n
While calculating RSA encryption key we take modulo(phi(n)) rather that modulo(n). I couldn't understand why its so?
1
vote
0answers
76 views
Two untrusted party want to exchange data: how to ensure each one gets the data it needs? [duplicate]
Possible Duplicate:
Two untrusted party want to exchange data: how to insure each one gets the data it needs?
I am trying to come up with what could maybe be a novel algorithm for an ...
4
votes
2answers
407 views
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.
3
votes
1answer
133 views
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 ...
6
votes
1answer
1k views
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 ...
8
votes
3answers
240 views
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 ...
20
votes
3answers
3k views
How can I use asymmetric encryption, such as RSA, to encrypt an arbitrary length of plaintext?
RSA is not designed to be used on long blocks of plaintext like a block cipher, but I need to use it to send a large message.
How can I do this?
