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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Retrieve value of private key after encryption with the public key

Is there a way to find an RSA private key after it is encrypted with the corresponding public key? Does there exist an algorithm to recover the private key in this special case?
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2answers
65 views

Key space vs Cardinality of 1024-bit RSA

I have been trying to figure out the encryption key space, and cardinality of 1024-bit RSA. From my understanding, the key generated from 1024-bit will be primes greater than $2^{1023}$ but less than ...
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48 views

Knowing N and a relationship between the 2 prime numbers(p and q) find p and q generated with RSA

Let there be $p$ and $q$, 2 prime numbers for which the following relationship is true: $|p-q| < 2 \cdot N^{1/4}$. The algorithm first generates the prime number $p$, then it generates $q$ close ...
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0answers
42 views

Why is the call to RSA_generate_key_ex() failing sometimes? [on hold]

I'm trying to randomly generate a pair of RSA asymmetric keys, however with my current implementation, the RSA_generate_key_ex() method seems to hang forever. I'm unable to extract an error code ...
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1answer
42 views
4
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1answer
180 views

Factoring two RSA modulus with known $|p_1 - p_2| < \ell $

I have two 1024bit RSA modulus $N_1 = p_1q_1$ and $N_2 = p_2q_2$ such that $0 <|p_1 - p_2| < \ell$, and $\ell$ is at most 64bit integer. Can I factorise $N_1$ and $N_2$? What's the answer when ...
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1answer
227 views

Timelock puzzle improvment

I came across this question with this answer about a cryptographic timelock-puzzle that needs approximately 30 years to be solved. There is also an explanation with source code for that puzzle ...
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1answer
48 views

Encryption & Decryption of Video using RSA [closed]

I need code in java for Encrypt & Decrypt any file using RSA Algorithm. I have code which takes a text file read data from it and then encrypt it. but I need program to encrypt mp3, mp4 any file.
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1answer
81 views

How multiplicative property of RSA can be exploited

It is known that RSA has the multiplicative property $E(m_1) \cdot E(m_2) = E(m_1 \cdot m_2)$ because $m_1^e \cdot m_2^e = (m_1 \cdot m_2)^e \pmod n$ But how can this property be used to break ...
2
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1answer
100 views

What use is the signature without the message under RSA?

Using RSA for signing & verification, is there a way to take a valid signature for an unknown message, and for someone else to generate a valid signature using a different key against the valid ...
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1answer
138 views

How to decrypt a '.enc' file that has been encrypted with RSA using a public key?

While solving a CTF challenge online, I came across a situation where I needed to decrypt a '.enc' file that has been encrypted using someone's public key. The ...
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1answer
108 views

Decrypted RSA 64 bit encryption using modulus and private exponent. Got gobbledygook [Verify] [closed]

As part of an experiment, I was given a .enc RSA (encrypted) file that was most likely generated using openssl. I had the public key, I factored it, obtained the private exponent, and decrypted the ...
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2answers
244 views

Toy public/private key example open to frequency analysis?

I've been looking at an online Public Key Encryption Example (summarized below). It seems to me that choosing cyphertext = plaintext^(key) mod n would produce the ...
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1answer
33 views

Identification by RSA

Suppose we have identification scheme as such: Bob takes random $r$, and encrypts it with Alices public RSA key $(n,e)$, sends $r^e$ to Alice. Alice decrypts $r$ and sends it back to Bob, becomes ...
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1answer
76 views

Asymmetric sign in public enviroment

I have RTS game, where all players run game and server just relays messages. Game can generate and store text file on player pc. I want to allow some players to be moderators, so I need to sign or ...
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1answer
41 views

How to choose the integer m in the general number field sieve (GNFS)?

Given an integer you want to factor $N$, GNFS starts by selecting a monic irreducible polynomial $f \in \mathbb{Z}[X]$ and an integer $m$ such that $f(m) \equiv 0 \text{ mod } N$. In practice, if $m$ ...
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3answers
576 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 ...
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1answer
131 views
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1answer
50 views

Openssl library problem

I'm using openssl library and I've a problem with RSA_private_encrypt() and RSA_public_decrypt(). I'm using a key size of 256 bit with no padding of the input message. I've noted that when my input ...
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2answers
64 views

Would the Fiat Shamir identification scheme be more secure if I design it with an exponents higher than 2?

Let's say both Prover and Verifier would use nth power instead of 2nd when creating public keys and when verifying. I know it would slow it down but would that cause the protocol to be more secure?
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0answers
38 views

RSA, proof of correct work, if p is not a prime number [duplicate]

Is there any proof of correct work of RSA algorithm, if p is not a prime number? For example: n = p*q, p = p1*p2, where p1 and p2 are primes. Edit: I found that it's called Multiprime RSA, but i ...
0
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1answer
39 views

Assemble RSA keys from components

I'm studying openpgp cryptography and struggling to understand some things. I can't use pgp tool for generating keys and ecryption, but have to write a simple app to generate keys, encrypt and decrypt ...
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0answers
39 views

RSA: If I know n, e, p, and q, how do I calculate d using the extended euclidean algorithm? [duplicate]

After doing a good amount of research, it's become fairly obvious that I ought to be using the extended Euclidean algorithm to calculate d from the data that I already have. However, this isn't an ...
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0answers
8 views

How to import key BLOB generated from Microsoft CryptExportKey from Linux [migrated]

I have a private/public key pair saved as key BLOBs which were in fact exported with the Microsoft "CryptExportKey" API. Now I need to use the same key pair (specially the public key) under Linux ...
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1answer
66 views

RSA weak padding

Suppose to have a function for numbers expressed in 8-bit $\in [0,2^8-1]$ defined as: $$f(x)=x||x||x||x$$ where $|f(x)|$ is exactly 32 bits. e.g., suppose x=2 (00000010) so ...
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11answers
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Now that quantum computers have been out for a while, has RSA been cracked?

D-wave systems has released a commercially viable quantum computer. This means in theory, that all asymmetric encryption algorithms — such as RSA — are now useless due to the speed at which quantum ...
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8 views

Using ssh agent to sign a string [migrated]

I am trying to learn more about asymmetric keys. I am writing a program that uses ssh-agent server to sign a message. This works well, but it generates a RSA-SHA1 signature of the message, which I am ...
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2answers
287 views

Practical Attack on RSA

Currently I am designing an RSA based application, and I am thinking of how long should the key be in order to be secure against attacks. I know that RSA 4096 bit key can be recovered using Sound ...
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4answers
3k views

Encrypting small values with RSA private key

I'm looking for best practices when it comes to encrypting small (< 128 bytes) amounts of data with the RSA private key. Signing it would make the resulting payload too large.
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1answer
121 views

Deterministically generate a RSA public/private key pair from a passphrase (with sufficient entropy)?

Is it possible to deterministically generate public/private RSA key pairs from passphrases? Would giving the (key generating) algorithm data made from key-stretching the passphrase (instead of a ...
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1answer
140 views

What prime lengths are used for RSA?

Let's assume we have an RSA 2048 that was produced by two primes multiplication. What is the digit's difference in those 2 factors? For example one prime is 1024 digits and second one 1024 or, one is ...
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4answers
966 views

Why are RSA key sizes almost always a power of two?

I know that other bit sizes are possible, e.g. this HTTPS server seems to have a 9000 bit key https://www.ssllabs.com/ssltest/analyze.html?d=qqq.gg, but it's very rare that one sees a key not of size ...
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31 views

Practical strength of non-2^n RSA key lengths [duplicate]

It has for many years been popular to use RSA keys that have lengths that are powers of two. E.g. 1024-bit, 2048-bit and 4096-bit key lengths are all popular for use with OpenPGP implementations such ...
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0answers
35 views

I was wondering if RSA is an homomorphic crypto system? [duplicate]

I was wondering if RSA is homomorphic and how secure is it. I have read there is a variable of this but i don't fully understand the mathematics.
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Is RSA-OAEP secure when e=3? [duplicate]

Is RSA-OAEP secure when the exponent is equal to 3?
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0answers
50 views

Given only RSA public key parameters, what security issues might I be able to detect?

I'm attempting to automate some checks against a large list of .NET assemblies, and want to include a test to see if the RSA parameters used to sign the assemblies are sensible. However, since I don't ...
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0answers
26 views

Where I can find a list of certified software / hardware RNGs compliant to NIST SP 800-22?

I need to use NIST SP 800-22 approved software / hardware to generate RSA key pair. Where I can find a list of certified software / hardware RNGs compliant to NIST SP 800-22? And how is the SP ...
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0answers
41 views

Requested to encrypt data with AES256, digital certification, timestamped

at my job we have been tasked by gov to encrypt some data we send to them. The "law" says we have to do the title above, but they only need us to do the AES256 thing because the data is not really ...
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1answer
72 views

decrypt a saml 2.0 response having aes 128 and rsa [closed]

I need to decrypt a saml 2.0 response. But, the response object has reference to aes 128 and rsa algorithms, and I am having hard time in finding a way to decrypt. Below is the structure of the ...
0
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1answer
48 views

RSA Decryption from samples

I am working on a project for a client which involves decryption of data which was encrypted using RSA. The system in question retains three independent copies of each data-set, but each copy is ...
3
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1answer
157 views

RSA key pair generation and FIPS 140-2, 186-4

I need to securely generate RSA key pair and I need to have access to private exponent in order to process it further. What's the difference in FIPS 140-2 and FIPS 186-4 in connection with RSA key ...
0
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1answer
104 views

Java RSA Padding: no libraries used

I'm trying to implement RSA without using any java libraries using the algorithm from wikipedia HERE So, anyone can clearly see that it is a raw RSA, and can directly be attacked. The question is ...
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2answers
110 views

Why is this a fix to Bleichenbacher's attack?

Looking at the excellent explaination of the attack here: Can you explain Bleichenbacher's CCA attack on PKCS#1 v1.5? I have one additional question: It says that: ""To prevent this attack, SSL ...
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1answer
47 views

RSA padding confusion attacks

Server A produces signed messages on request. You can tell server A what type of RSA padding to use in the signature (either RSASSA-PKCS1v1_5 or RSASSA-PSS). Either way, the message will be signed ...
0
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1answer
66 views

Fault encryption attack on RSA [duplicate]

How to recover plaintext, if we know public key(RSA), correctly encrypted text and text encrypted with faulty public key, where one bit is changed?
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0answers
40 views

Is the half-homomorphic property of RSA a problem for blind RSA signatures?

For blind RSA signatures, is it problematic that RSA is half-homomorph? Take a scenario where blind RSA signatures are used for something like a voting procedure or this proposal: Lots of people, ...
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11k views

How does RSA signature verification work?

I understand how the RSA algorithm works for encryption and decryption purposes but I don't get how signing is done. Here's what I (think) I know and is common practice: If I have a message that I ...
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2answers
592 views

If we can find prime numbers larger than 17 milion digits, why can't we find all 1024bit primes? [duplicate]

"Largest Known Prime Number Discovered; Has 17,425,170 Digits" http://www.sciencedaily.com/releases/2013/02/130213225424.htm If we can find prime numbers larger than 17 milion digits, why can't we ...
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1answer
57 views

RSA Key composition

I'm trying to figure out how it is composed the RSA key. Follow what I know : For a RSA 2048, 2048 is the bit length of the module. The public key is composed by $(e,M)$ when $e$ is the public ...
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1answer
63 views

Convert numeric message from RSA ciphertext to alphabetic

I have a set of numeric values that are supposed to represent a message encoded via textbook RSA. For example: 60889 37946 13359 61629 35960 13747 I've decrypted ...