Linked Questions
30 questions linked to/from Definition of textbook RSA
35
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5
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Why is padding used for RSA encryption given that it is not a block cipher?
In AES we use some padded bytes at end of message to fit 128/256
byte blocks. But as RSA is not a block cipher why is padding used?
Can the message size be any byte length (is the encrypting agent
...
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6
votes
4
answers
12k
views
Is it safer to encrypt twice with RSA?
I wonder if it's safer to encrypt a plain text with RSA twice than it is to encrypt it just once. It should make a big difference if you assume that the two private keys are different, and that the ...
- 223
2
votes
3
answers
2k
views
Input limitations on the RC6 cipher
RSA has limitation in input size for encryption and decryption.
Can RC6 be used for encryption and decryption of files larger than 5 MB?
Is there any limitation for input size?
Is RC6 safe for using ...
- 368
30
votes
2
answers
22k
views
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).
Which ...
27
votes
2
answers
38k
views
When to use RSA and when ElGamal asymmetric encryption
If i am not wrong in cryptography there are 2 basic cryptographic schemes for public key cryptography. RSA encryption whose security is based on the infeasibility of solving the factoring of big ...
- 6,160
11
votes
2
answers
3k
views
In textbook RSA with low public exponent, how big does a random message needs to be?
Assume RSA with a public modulus $N$ of $n$ bits, a small odd public exponent $e$, plaintext $M$ a random non-negative integer less than $2^m$ for some integer parameter $m$, with $M\mapsto C=M^e\bmod ...
- 141k
3
votes
2
answers
215
views
Help with RSA step
There's one thing in RSA that haunts me. In books there's just a statement, that
$$ed \equiv 1 \bmod \varphi(n)$$
is taken from Euler's function somehow. And than we use it to get
$$m^{ed} \equiv ...
- 115
3
votes
2
answers
846
views
Does order matter for RSA when used multiple times?
I actually have no idea how RSA works, but I currently (think that I) know
Public and private keys are mathematically doing their opposites
Therefore, the order in which they are applied doesn't ...
- 133
2
votes
2
answers
5k
views
RSA PCKS1 v2.1 RSAES-OAEP algorithm
Using RSA public key (n,e) the encryption of a message is
c= (m^e) mod n
and the corresponding message is decrypted as
...
- 189
2
votes
2
answers
17k
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OTP from Sony BIOS password recover [closed]
From Dogbert's blog:
Sony has a line of laptops ("Vaio") which compete mainly in the high value market segments. They implemented a master password bypass which is rather sane in comparison to the ...
- 121
1
vote
2
answers
69
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RSA: does it matter that we recover something congruent to x rather than equal to it?
In the proof that RSA successfully decrypts the message $x$, we show that $x^{e^{d}}\equiv x \pmod N$. However, I am wondering whether it is a problem that we don't recover $x$ exactly, but merely a ...
- 123
1
vote
2
answers
485
views
Stuck on a cryptanalytical research project [closed]
This is not a technical question, but rather it seeks advice on what to do if cryptanalytical research goes wrong.
I've discovered a new attack that works great in theory, but in practice, it fails.
I ...
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11
votes
1
answer
12k
views
Are there comprehensive alternatives to RSA?
If we wished to, is there a comprehensive alternative to RSA?
I say comprehensive as I wonder if there is one which does both encryption and digital signature like RSA?
If not, simply what ...
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6
votes
1
answer
5k
views
Get RSA PlainText without Knowing Private Key
If I have an algorithm,RSA-Crack(), that, for a given RSA public key (n,e), is able to decrypt 1% of the messages encrypted with that key (without knowledge of the corresponding private key).Can there ...
- 163
4
votes
1
answer
15k
views
Is it true that for RSA with no padding, the length of data must be equal to the length of key?
The question pertains not in terms of security but computing operational functionality, as it how the computation is done.
Is it true that for RSA with no padding, the length of data must be equal to ...
3
votes
1
answer
12k
views
1
vote
1
answer
114
views
RSA: in $E(x) \equiv x^e \pmod N$, do we apply the mod function to $x^e$?
When one is computing $E(x) \equiv x^e \pmod N$ (where $N = pq$) in RSA, what is the precedent for which number in the residue class of $x^e$ to have as the result of this computation? Does this mean ...
- 123
1
vote
1
answer
194
views
Does an binary elliptic curve like sect571r1 support a bijective asymmetric operation pair on bytes? If so, is there a self-contained example?
I'm wondering if a binary elliptic curve (such as sect571r1 aka B-571) supports pairs of asymmetric operations (for example, either sign/verify or encrypt/decrypt) on a fixed bit or byte input size in ...
- 111
1
vote
1
answer
694
views
Is it secure to use RSA to exchange AES key?
I have to create a Client-Server Application using Java and I want to make the communication secure. I thought to use AES to encrypt the messages and for key exchange I make the next steps:
Client ...
- 11
1
vote
1
answer
142
views
special public keys and modulo n
I just picked up cryptography and have some questions on RSA cryptosystem:
Say there are two public keys (n, e1), (n, e2), e1 is coprime to e2. They share the same n. Is it possible to find the ...
- 111
1
vote
1
answer
3k
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OpenSSL RSA same plaintext but different ciphertext
how OpenSSL RSA work ?
I generate public (n,e) and private key (n,d) then I encypted a file by :
...
- 61
1
vote
1
answer
9k
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Textbook RSA with exponent e=3 [duplicate]
I remember $e=3$ is a bad choice for textbook RSA. But I can't really recall why. What happens if I choose $e=3$? Can I retrieve the message by simply calculating $\sqrt[3]{c}$? Why can't I do that ...
- 569
0
votes
1
answer
255
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RSA - encrypted plaintext results in the same ciphertext value
Just started learning about RSA cryptography so forgive me if I made any mistakes or misunderstandings.
M = 20 be the message that i want to encrypt
N = 5*7 , p = 5 and q = 7
φ(N) = (5-1)(7-1) = 24
...
0
votes
1
answer
1k
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RSA How to select a value K such that $e d = 1 + k \varphi(N)$ holds
I am learning RSA cryptography. The part I am stuck on is understanding how k and the public exponent $e$ is selected.
Given the formulas;
Decrypting: $c^d \bmod N = (m^e)^d \bmod N$
Which is equal ...
- 115
0
votes
1
answer
2k
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RSA encryption/decryption process is not working correctly
I'm trying to apply the RSA cryptosystem to encrypt a byte M=72, using predefined modulus n, public key exponent ...
- 111
0
votes
1
answer
2k
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I think I'm trying to find the C in an RSA cipher to find the key for an aes_128_ecb cipher, can anyone tell me if I'm on the right track?
And if I am on the right track, how do I reach the solution from here?
I'm doing a CS game and I've hit a wall (I'm a rank beginner when it comes to encryption) on the encryption portion. I've been ...
- 13
-1
votes
1
answer
10k
views
Why plain RSA encryption does not achieve CPA-security?
Why plain RSA encryption does not achieve CPA-security?
- 27
-1
votes
1
answer
921
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RSA problem - how to find $d$ [duplicate]
For example, let $p = 3$ and $q= 11$, choose $e = 3$. What computation I have to apply in order to find the corresponding $d$? I know it's 7, but I want to know the exact process to be applied to find ...
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-3
votes
1
answer
661
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How does the math part of RSA work? [duplicate]
I understand the theoretical part of RSA (the concept of public and private keys), but I don't understand the mathematical part. Can anyone please explain it to me in simple terms? Thanks.
1
vote
0
answers
110
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How secure is 'Plain Old RSA' [duplicate]
Let's say I use RSA encryption, it's 2048 bits and I use a simple character padding scheme, every character is turned into a 3 digit number and strung together, then encrypted. Saying that no message ...
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