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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1answer
497 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
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3answers
319 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 ...
2
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4answers
858 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
154 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
337 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
953 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
325 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
753 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 ...
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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
241 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
492 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 ...
3
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2answers
134 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
172 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
votes
1answer
154 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
117 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
198 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 ...
0
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1answer
219 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 ...
6
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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
236 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
945 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
136 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
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 ...
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2answers
92 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
225 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
votes
2answers
725 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
385 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 ...
6
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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?
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2answers
123 views
Idea for secure password hash-likes, is this feasible/usable/workable?
(Hand moved from stackoverflow.com,due to suggestion)
Since breaking password hashes has become a new passtime for scriptkiddies, I thought of the problem and came up with a novel(?) idea.
store ...
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0answers
120 views
RSA SecurID: Unable to access via web manager [closed]
I'm having an error with access to the web admin of my RSA SecurID server.
I'm getting an error of 100: access denied. The RSA ACE/Server rejected the passcode.
I'm guessing that this is most likely ...
2
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2answers
189 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 ...
1
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1answer
180 views
“Signing” with public key
For this question, the following caveats and assumptions hold:
There exists a 2048-bit RSA key pair used exclusively for signing/verification
The private key is kept completely private
There exists ...
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2answers
99 views
When to prefer exchanging cryptographic certificates over exchanging only public keys?
Let's think of the following case:
A group of peers want to exchange messages with each other. They use public-key cryptography to sign and encrypt messages. Anyone with any name can join the ...
3
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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
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1answer
268 views
What is the harm if I publish an encrypted RSA private key publicly?
What is the harm if I publish an encrypted RSA private key publicly? Or in this case, what is the harm if I publish many thousands or millions of them?
Assuming that the private key is encrypted ...
3
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2answers
460 views
Difficulty of breaking RSA for a given key size
Is it true that breaking a 1024-bit RSA key is as difficult as breaking a 128 bit symmetric key (e.g. AES)? I know that breaking a RSA key is equivalent to factoring the modulus $N$. To factor it, you ...
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2answers
543 views
Why DSA cannot be used for encryption?
Here it is mentioned that DSA cannot be used for encrypt. But Both RSA and DSA can be used to generate public and private keys, right? (Or am I wrong?). Then why can't I use the DSA public key to ...
5
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1answer
830 views
Chinese Remainder Theorem and RSA
Wikipedia has a nice section regarding the speedup of the RSA decryption using the Chinese Remainder Theorem here. I need to understand the implementation of a similar speedup for the encryption ...
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1answer
107 views
How can we find Public key have only 8 or 16bits? How many messages does Eve need to know the Public key in RSA?
Suppose Alice sends messages to Bob by encrypting the messages with Bob's public key.
Eve knows that the data is encrypted using RSA, but does not know the public key. Can Eve figure out the public ...
2
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0answers
112 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 ...
2
votes
1answer
291 views
How many RSA keys before a collision?
I was wondering how many possibilities of private/public keys there are? If a million people for whatever reason tried to generate 5keys each in the same minute (on the same date and time) is there a ...
1
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1answer
2k views
OTP from Sony BIOS password recover
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 ...
8
votes
2answers
763 views
Can two different pairs of RSA key have the same modulus?
Can $n=pq$ be part of two different pairs of RSA keys?
If such keys exist, say $(e_1,n)$ and $(e_2,n)$, how are they related?
What will be the security concerns for the two users?
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3answers
467 views
Why hash or salt when signing?
I've seen an example of how to sign using RSA. Besides the signing itself (s = m^d mod n) it also hashes and adds an IV.
Why is that needed?
5
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1answer
276 views
Are there any MGF1 and OS2IP functions available in C?
I need MGF1 and OS2IP functions, as defined in the PKCS #1 v2.1: RSA Cryptography Standard.
Is there anything available in OpenSSL, or any other open C library?
3
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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
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1answer
426 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 ...
