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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237 views
Constructing RSA private key, given public key
As part of a puzzle I was given an RSA 256-bit public key and an encrypted message.
The key itself is very weak, having exponent e = 65537 and modulus N = ...
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0answers
78 views
Actual weakness RSA [closed]
I need modern trends analysis RSA. Hinek books "Cryptanalys RSA and Yan "Cryptanalytic RSA" have been read. What else?
4
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2answers
278 views
Are there any standards of multi-prime RSA key generation?
FIPS 186-3 specifies a method to generate DSA parameters.
Is there anything similar (official standard or widely-accepted recommendation) that shows how to generate the primes for multi-prime RSA?
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2answers
522 views
Decrypt digital signature using RSA public key with openssl
I have a digital signature that was created using the following algorithm: a SHA-256 hash of the body of the message is calculated. It is then signed using an RSA private key and the result is ...
2
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0answers
104 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 ...
4
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1answer
128 views
Why does OAEP have 2 rounds with 2 random oracles?
I strive into understanding why OAEP has two rounds of computations and not just one. I.e: Wouldn't it be safe to hash the random number r and XOR it with the original message?What security risks if ...
2
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3answers
621 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 ...
0
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1answer
167 views
What is a trapdoor permutation?
Can anyone explain to me what a trapdoor one-way permutation is? Is RSA a trapdoor one-way permutation?
Context: I was reading about ring signatures. On page 560, it describes steps to ...
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2answers
120 views
Breaking RSA, given a special kind of oracle that decrypts related ciphertexts for us
Let $c=E^{RSA}_{e}(w)$ be the ciphertext belonging to the plaintext $w$ if an $RSA$ system is used. Assume that the public exponent $e$ satisfies $e \le 10$. Furthermore, assume there is an oracle ...
4
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2answers
357 views
RSA and prime difference
It is known that the two prime factors $p$ and $q$ of an RSA modulus $n$ should not be too close to each other, otherwise an attacker may factor the modulus. In other words, $\Delta = \left| p - q ...
6
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4answers
408 views
Is an RSA variant with public exponent $e=f+(p-1)\cdot(q-1)$ safe (for $f$ random in some small interval)?
Alice is going to use some existing RSA scheme (employing industry-standard signature or/and encryption with proper padding), which she can't change, or influence beyond her choice of key. In this ...
2
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1answer
140 views
Why do we need in RSA the modulus to be product of 2 primes?
I think I roughly understand how the RSA alorithm is working.
However, I don't understand why we need the $N$, which we use as a modulus, to be $pq$ for some large primes $p, q$.
I vaguely know it ...
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2answers
124 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 ...
3
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1answer
172 views
What's the main difference between Pohlig-Hellman and RSA?
Both Pohlig-Hellman and RSA perform encryption and decryption by exponentiation modulo some integer ($p$ prime for PH, $n$ composite for RSA). They both use a key $e$ as the exponent to encrypt a ...
1
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1answer
109 views
RSA encryption input range - plaintexts that map to ciphertexts?
According to the wiki article on the RSA encryption function, the valid range of input $m$ is $0 \leq m \lt n$. However I have found that the following values of $m$ always return themselves when ...
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3answers
497 views
Is 512-bit RSA still safe for signature generation?
The standard CSP on Windows XP only supports RSA up to 512-bit, which means that it's the maximum key size I can use for authenticity verification of updates. The public key is embedded in the ...
2
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1answer
164 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 ...
3
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1answer
221 views
is this RSA private key valid?
is this RSA private key valid?
First, here's the RSA private key in question:
...
2
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2answers
466 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 ...
8
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2answers
481 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
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1answer
507 views
ABC Conjecture's Impact on RSA Encryption
A recent proof of the ABC Conjecture has been released by one Shinichi Mochizuki. Now, I'm not well versed in mathematics but it would appear that this proof implies that finding prime factors could ...
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1answer
88 views
modulus condition [closed]
In RSA algorithm, the modulus $n$ should be chosen based on the below condition
$2^{8(k-1)} \leqslant n < 2^{8k}$
Where $k$ is the byte length of the modulus $n$.
for this condition I want the ...
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2answers
66 views
find solutions that solve the equations
I am implementing a timing attack on RSA for school and I need to generate two sets of messages $Y$ and $Z$ for which holds:
$ (Y^d \mod N) \cdot Y < N $ and
$ (Z^d \mod N) \cdot Z > N $
where ...
3
votes
3answers
336 views
How do ciphers change plaintext into numeric digits for computing?
For example, in RSA, we use this for encryption: $ciphertext = (m^e \mod n)$ and for decryption.
If our message is "hello world", then what number do we have to ...
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4answers
1k views
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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1answer
162 views
RSA 1024bit decryption performance
i want to know how many RSA 1024 bit long key decryption can a regular pentium4 computer do per second ? how to calculate RSA performance and determine its remaining time ?
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2answers
362 views
Homomorphic cryptosystems in RSA
Hopefully Crypto can help me understand homomorphic cryptosystems.
I'm designing a high score server for a game I made, and because of facets in the language i'm using, the player would be able to ...
4
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1answer
1k views
Common modulus attack on RSA when the 2 public exponents differ by a single bit
This is an exam question an i have no idea how to recover the message m.
John wants to send an encrypted message to mary who has a pair of RSA keys, However, John does not know Mary's public key and ...
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3answers
349 views
What is the length of an RSA signature?
Is it the same as the bits of the key (So a 2048 bit system will yield a 2048 bit signature)? At most as the key? Or something else entirely?
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1answer
50 views
Design question for a service that signs messages on behalf of a user
I'm working on a messaging service that lets users author messages and have them signed with an RSA key. The key is used for identity purposes only and can be revoked, so compromising the private key ...
1
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2answers
811 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 ...
0
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1answer
78 views
inverse of 985 mod(φ60131)
Alright Ive been working on this one for a while
I found φ(60131) to be 97294
½(60131+60131(5)^.5) = 97294
then I worked through the GCD
...
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1answer
261 views
How to jusify {e,n} is a valid RSA public key?
I have a two set of key {36,77} and {50,117},
How can validate if it is a valid RSA public keys?
Is there any simple method?
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2answers
525 views
Why should the RSA private exponent have the same size as the modulus?
Consider the generation of an RSA key pair with a given modulus size $n$ and a known, small public exponent $e$ (typically $e = 3$ or $e = 65537$). A common method is to generate two random primes ...
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2answers
138 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 ...
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2answers
2k views
Signatures: RSA compared to ECDSA
I'm signing very small messages using RSA, and the signature and public key are added to every message, which requires a lot of space compared to the actual content.
I'm considering switching to ...
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2answers
176 views
Encryption with private key?
we normally always encrypt by public key and decrypt with private key.
If i encrypt with private key, then its still secure as normal PKI ?
i mean known-plain-text will not take private key on the ...
3
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1answer
157 views
RSA algorithm's license free or paid?
I checked RSA's patent application, which was registered in 1983. As patents don't last more than 20 years, it seems to me it should be free. But my friend said to use RSA I have to buy a license from ...
2
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2answers
120 views
Does a high exponent compensate for a low degree of certainty?
If a RSA certificate is created with a low degree of certainty, does the value of the exponent compensate for this?
I'm asking because certain implementations of key generation software hide the ...
2
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2answers
202 views
How to decrypt this RSA-like cipher
Suppose we have a RSA-type Modulus $n = pq$ with $p,q$ prime. We also pick a random public exponent $e$ with $\gcd(e,\varphi(n)) = 1$ and compute the private exponent $d$ with $de \equiv 1 ...
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1answer
243 views
What is the correct value for “certainty” in RSA key pair generation?
I'm creating an RSA key pair in Bouncy Castle and need to specify an int value for certainty. This Stack Overflow answer says it is a relative test for how prime the values are.
There is another ...
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2answers
1k views
Impacts of not using RSA exponent of 65537
This RFC says the RSA Exponent should be 65537. Why is that number recommended and what are the theoretical and practical impacts & risks of making that number higher or lower?
What are the ...
3
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2answers
239 views
How does the cyclic attack on RSA work?
I am trying to get the idea of cyclic attacks againts assymetric RSA encryption.
Taken from Handbook of applied cryptography .
Let $k$ be a positive integer such that $$c^{(e^{k})} = c\mod n ...
2
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2answers
1k views
How much computing resource is required to brute-force RSA?
It's been over 30 years since Rivest, Shamir and Adleman first publicly described their algorithm for public-key cryptography; and the intelligence community is thought to have known about it for ...
2
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2answers
138 views
Is there a way to compare the 923 bit pairing based key with RSA or AES, etc
I've see many articles, most of them basically the same, praising Fujitsu for cracking what is referred to as a 923 bit pairing based encryption. I understand that in comparing RSA to AES you've got ...
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1answer
121 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 ...
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2answers
96 views
Distinguishing Encryption Methods from the Output
Suppose that you see all IP communication packets between two computers for a day, as they pass through a connecting router, and this amounts to 10MB. You additionally know that all data transmission ...
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2answers
229 views
Is it possible to use the RSA algorithm, or a variant, for software licensing?
I'm almost a newbie about RSA encryption, so my question could it be banal.
I'm beginning to create a licensing system for my software.
I need to distribute a crypted license file to many customers.
I ...
3
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2answers
809 views
How do digital certificates work, and why is it not possible to reverse engineer one from a signed file?
Digital certificates are used quite commonly these days, for signing files. They are used by various operating systems to ensure reliability and security. For example, Android requires that each of ...
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2answers
448 views
RSA Proof of Correctness
Can anyone provide an extended (and well explained) proof of correctness of the RSA Algorithm?
And why is it needed?
I can't say that this or this helped me much, I'd like a more detailed and newbie ...
