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Questions tagged [rsa]

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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Is RSA provably secure in the sense of Douglas Stinson's ``provable security''?

Here's a quote from Douglas Stinson: “[i]f a cryptosystem can be ‘broken’ in some specific way, then it would be possible to efficiently solve some well-studied problem that is thought to be ...
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Is it possible to generate same RSA key on purpose?

I want to ask if I have a RSA private key can I use it to generate RSA key that is identical. If yes how can I do it?
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Can you tell how many times data has been encrypted?

I'm using multiple RSA keys to encrypt a piece of data. The data length is constant but the data itself is not. Each time I encrypt I prepend a 64 bit string to the newly encrypted ciphertext. This ...
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Can we find the exact number given remainder of the numbers with mod m?

I have around 1500 numbers. The numbers $x_i$ are calculated as $x_i$=($p*t_i$) mod m. $p$ constant and same for all the numbers while $t_i$ are chosen randomly everytime. For example the given ...
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RSA restore part of D from E and N

I have full N and e part of my RSA private key. Also, I have the most of my D part. Just lost several bits in the start of D part. Can I restore the whole RSA private key from that data and use it ...
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The 9 lives of Bleichenbacher's CAT, it puts another scratch again

Bleichenbacher demonstrated a padding oracle attack against RSA implementations that follow the PKCS #1 v1.5. Through the years, there are various mitigation techniques developed as OAEP and limiting ...
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Find factor of a numbers of around 3500 bit long, given 1000 such numbers. Each number is product of s*p, p is constant and s is randomly chosen

Given 1000 numbers of form s*p, number are of 3500 bit long. How to factor these numbers? s and p are not necessarily prime numbers. p is constant for all numbers and s is randomly chosen for all ...
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RSA engine with inaccessible private keys - susceptible to any attacks?

We are going to integrate some hardware accelerator for RSA into our next system on chip. This chip can accelerate the core RSA operation, i.e. modular exponentiation $y=A^x \mod(N)$. The private key (...
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RSA limiting down the possible values for $n,q$, and $d$? given only $e$ and $p$ [duplicate]

Suppose someone forgot the value of $n$ and you only knew the values for $e$ and $p$. How could one go about limiting down the possible values for $n,q$, and $d$? I'm thinking to try and solve $\gcd(...
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RSA find $q$ given only $e$ and $p$

Lets say hypothetically all one knew was a value of $e$ and a value of $p$. As an example, lets assume that $e = 13$ and $p = 67$. Would it be possible to find the value of $q$ from this equation? ...
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Send content to owner of gpg public key, nested content symmetric encryption

If I want to encrypt a text content file using a symmetric algorithm like AES, is there a standard format gpg will expect, where it can detect a symmetric key (encrypted with recipient gpg public key ...
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Equivalent RSA modulus for NIST P-192 and P-521 elliptic curves [duplicate]

At www.keylength.com, I found the following table of ECC field size and the corresponding RSA modulus recommended by NIST. ECC Modulus RSA Prime Size 160 1024 224 2048 ...
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Performing a dictionary attack on RSA/ECB with no padding

I have the exponent $e=2^{16}+1$ and modulus $n$ (154 digit number) of an RSA public key along with the ciphertext (64 bytes) encrypted using the same key with RSA/ECB and no padding. I am required ...
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RSA PSS security advantage

To my humble opinion, please correct me if I'm wrong, RSA-PSS (PKCS#1 ver 2.1) advantage over RSA as described in PKCS#1 ver. 1.5 is in its security proofs. Does this proof and the advantage is still ...
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What exactly is an RSA UFO and what are its cryptographic properties?

I recently read a page describing what is called an "RSA UFO", or "generalized RSA moduli of unknown complete factorization". Though they practically spell out the properties and generation algorithm ...
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For elliptic-curve cryptography, does a 256-bit key imply that $x$ and $y$ are each 256-bits or 128-bits?

In the wikipedia article, the claim is made that "256-bit elliptic curve public key should provide comparable security to a 3072-bit RSA public key". Since, in ECC, the public-key consists of a point $...
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Recover message in RSA-OAEP with fixed seed

In RSA-OAEP given a fixed and a known value for the seed, is it possible to recover message using its ciphertext and the public key $(n,e)$?
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Unable to reproduce correct signature data

"Skatteetaten" is the Norwegian tax authority. We're currently trying to implement signing of messages for digital cash registry systems and i'm not able to reproduce the desired signed data. Went ...
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What is the best way to sign a message using RSA?

I was preparing for competitive exam, and I came across this question. I had a lot of discussion with my friends before I resorted to posting it here and I wanted myself to be clear on this. Let $M$ ...
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RSA: Is there a way to increase the partially encrypt data without knowing the private key?

EDITED QUESTION FOR A BETTER EXPLAINATION I have this crypted information (RSA): ...
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Sharing RSA private key between SSH and SSL services. How bad is it?

An appliance uses a curious way of obtaining ssh-rsa host keys: There is a single configuration option "management certificate" that sets RSA private keys both for HTTPS and SSH management. ...
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Best way to attack a small e and small m RSA problem?

I am working through a series of crypto exercises to learn a bit more about RSA and crypto in general. In the case where one has a small $e$ AND a small m, would it be correct to say that if $m<N^{...
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Is there a variation of Coppersmith's method that applies to disjoint variable set with additional control?

We have a polynomial $f(x_1,x_2,x_3,x_4)\in\mathbb Z[x_1,x_2,x_3,x_4]$ where the only monomials are either from set $$\{x_1,x_1x_2,x_2,x_3,x_3x_4,x_4\}$$ and we seek solutions $(x_1,x_2,x_3,x_4)\in\...
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Proof of concept for RSA malleability

I'm trying to see how easy RSA malleability is. I generate 2 ciphertexts with a public key: ...
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RSA encrypting private keys blinding

I am studying RSA couldn't understand this question: Alice encrypts the private factors of the modulus using her private key. In order to increase security, she multiplies them with a random integer $...
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Why does the Node crypto library do Diffie Hellman this way?

I was sifting through the Node Crytpo library and I came across their Diffie Hellman utility class. Their class implements a generateKeys function that, in their ...
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brute force RSA [closed]

I have a ciphertext c_t and a RSA public key pair (e, n). I also know that the encrypted message is a three-letter word in the ...
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Input limitations on the RC6 cipher

RSA has limitation in input size for encryption and decryption. Can RC6 be used for encrytion and decryption of files larger than 5 MB? Is there any limitation for input size? Is RC6 safe for using ...
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Size of group for Elliptic curves vs RSA for equal security

For my research, I would like to compare the efficiency of a scheme when instantiated with Elliptic curves and RSA. So, I would like to know a "latest" comparison (as of 2018) on what group sizes of ...
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Is RSA inspired by Diffie Hellman?

I read a bit of A Method for Obtaining Digital Signatures and Public-Key Cryptosystems that introduced RSA in 1977, and, while learning the steps in RSA a few days ago, I noticed that they are similar ...
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Inclusion and Exclusion proofs in RSA accumulators

I am reading about RSA accumulators from this video and few other sources. I had a confusion whether the complete set is needed to construct a proof of inclusion/exclusion in an RSA accumulator or is ...
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Cost of multiplication when e is randomly selected. RSA

Using schoolbook multiplication (which has cost $\mathcal{O}(n^2)$) to multiply two $n$-bit numbers) what is the cost of computing an RSA encryption with $e = 3$? What is the cost if $e$ is chosen ...
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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 ...
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How much data can I encrypt with RSA before I need to change the key

How much data can be encrypted with the same RSA key before it has to be changed? I looking for the total amount of data that can be encrypted for a single key pair, not the maximum length of data ...
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RSA - Does knowledge of part of the ciphertext decrease encryption security for the rest of the ciphertext?

There is a language called SystemVerilog that can be protected via encryption to allow sharing/licensing code for others to use, but prevents them from seeing the code contents. This is done based on ...
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Which algorithm to use for S/MIME

I'm wondering if the algorithm 1.2.840.113549.1.1.1 (rsaEncryption) is still secure to use for S/MIME encryption. I'm afraid that the scheme is vulnerable against ...
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Advantages and disadvantages of multiprime RSA [duplicate]

What if in RSA $N = pqr$ except $N = pq$? I know that this will also work. But what exactly are the advantages and the disadvantages of this? Could you give me at least one of each?
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Need a test suite for my RSA implementation

I have an assignment to build a software which can encrypt/decrypt by RSA method. I already did it, but my teacher said that I need to find a test suite (include: modulus, public key, private key) to ...
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Is the only use for the private key of a root certificate signing certificates issued by it?

A root certificate can be used to issue intermediate certificates. The private key of the root certificate is needed in order to sign any intermediate certificates. However, after that, we only need ...
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How might one create a system of election by lot (sortition) that is both secure and verifiable?

I've been puzzling recently over sortition, a democratic method of selection for public office which I find very fascinating. Basically, instead of choosing candidates like Hillary Clinton or Donald ...
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How do we know if we have successfully decrypted something?

Suppose for any given typical Bob, Eve and Alice encryption example where Bob and Alice exchange information using RSA. Bob encrypts his message using Eve's public key and sends his message off to ...
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Are the Common modulus attack, Common Factor Attack, and Wiener's attack different?

Is there a difference between: Common modulus attack Common Factor attack Wiener's attack or are these just a different name for the same attack?
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Upper bounds on difference of RSA primes

I was wondering whether given a concrete $N = p \cdot q$ whether we can find a upper bound on $\Delta = | p - q|$ as function of $N$ e.g, $N^\delta$, and thus test whether a given $N$ is vulnerable ...
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Fault attack on RSA-CRT

I am trying to understand fault attack on RSA-CRT, and I found some example, which I don't know how to solve it. I know public modulus $N$, public exponent $e$, a value of faulty signature (where ...
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What is the computational complexity of Coppersmith's bivariate algorithm?

Coppersmith's original paper Finding a Small Root of a Bivariate Integer Equation; Factoring with High Bits Known says the algorithm to find bivariate roots under certain conditions runs in ...
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RSA finding p and q integer with condition

I'm given $N=p\,q$ and told that $44\,p\approx 17\,q$ (with the value given for $N$ some 49-digit integer 8124642558124642555899928124642555899924479992447). In ...
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RSA - Finding all possible encryption exponents

Consider the standard RSA-algorithm: We have chosen two primes $p$ and $q $ such that $n:=p \cdot q$ and computed $\varphi(n)$. We now need to choose the public key $e$ such that $$1<e<\varphi(...
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How to encrypt file with RSA and AES that anyone with RSA key can decrypt them?

How to encrypt a file with RSA and AES-256 that anyone with RSA key can decrypt them?.
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Attack on RSA when I know $e$, ciphertexts $c_1, c_2$ of the same message $m$ with 2 coprime modules?

I know that the same message $m$ was sent to two people resulting in ciphertexts $c_1, c_2$. The public keys are $n_1$ and $n_2$, $gcd(n_1, n_2) = 1$. And $e=3$ in both cases. How can I retrieve the ...
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RSA most significant bit oracle attack

I have been reading up on RSA attacks and came across a problem that could be called a most-significant-bit (MSB) oracle attack. For the sake of clarity, let's define RSA primes $(p, q)$, private key ...