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 with proper paddings.
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Completing RSA Encryption
Being new to cryptology, I'm trying to understand how I would complete RSA encryption by hand.
I can only follow the formula so far before becoming very confused.
I want to encrypt the value "123&...
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PRNG For RSA (ANSI_X9.31)
I have a query please , I want to know how to generate random numbers using ANSI_X9.31 algorithm for RSA Algorithm please .
Thank u
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Why does it take more time to decrypt the same file with 256 bit RSA in TEE than in REE?
We all know that TEE can utilize almost all of the CPU's performance, so its time spent encrypting files using RSA256 is less than that of REE.
But why isn't decryption?
Why does it take more time to ...
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RSA public key identification
Consider a multi party system where public keys of all receivers are known. Server wants to send message to one of them using (textbook?) RSA. Adversary is given ciphertext and even Message to be send,...
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How can a recipient recognize which encrypted messages are intended for them?
Let's say there's a decentralized email service where parties' public keys are known. A sender sends a message to a recipient by encrypting via RSA with the recipient's public key and posting the ...
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Reveal a plaintext with 3 encryptions of Textbook RSA
Assume we using Textbook RSA encryption with the public key $(N,3)$.
How can I learn message $m$ if I have the encryptions of $m,m+1,m+2$ in an efficient way?
I'm studying for a test and it's a ...
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Generating a SHA256 pkcs1v1.5 Blind RSA Signature using Chaum's Blind Signature Scheme
I am a noob to cryptography in the sense that I have only little understanding as to how RSA encryption schemes work in practice. However I do understand the theoretical foundations of RSA ...
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How to calculate number of possible key pairs in RSA
What determines the number of possible RSA key pairs for a given $n$?
Is it because $\varphi(n)$ produces the number of values that are less than $n$ and coprime with $n$?
Is it as simple as $\varphi(...
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Need help to understand this RSA common modulus attack Python code
I am reading Practical Cryptography in Python. I have problem understanding the common_modulus_decrypt() function. I think the prerequisite of RSA Common Modulus Attack is that two public exponents ...
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Standard tools for deterministic RSA key generation using seed?
I'd like to resuse the mnemonic I have from bip39 for crypto in other domains such as ssh and tls, etc. Are there standard tools (ie, openssl) to deterministically generate rsa key/pairs given a seed ...
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If we have multiple unique RSA signed messages produced from the same private key, can we always find new valid signatures?
Say Alice publishes $t$ unique signed messages with her private key $d$,
$$
m_1^d, m_2^d, m_3^d, ... , m_t^d \mod n
$$
For $t = 2$, we have $m_1^d, m_2^d \mod n$ and if we let $x \equiv m_1m_2 \mod n$ ...
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RSA algorithm implementation
$$m^{ed} \equiv m \bmod n$$
$n =pq$, so by Chinese Remainder Theorem it is equivalent to
$$m^{ed} \equiv m \bmod 𝑝, m^{ed} \equiv m \bmod q$$
where $n=p\cdot q$
So how did 2 come from 1 by the ...
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How to Update Non-Membership Witness upon deletion in RSA Dynamic Universal Accumulator
The Universal Accumulator paper mentions the following for updating non-membership witness upon member deletion.
Choose $r$ such that $a\hat x − rx ∈ Z$$2^l$
What is Z$2^l$ and how can we ...
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Why $f(x)=x^e$ is a bijection i.f.f $e\in{\mathbf{Z^*_{\phi(N)}}}$?
I understand that if $e\in{\mathbf{Z^*_{\phi(N)}}}$ then $\gcd(e,\phi(N))=1$
and if $e\not\in{\mathbf{Z^*_{\phi(N)}}}$ than $\gcd(e,\phi(N))\neq{}1$.
But I couldn't figure out why this implies ...
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RSA assumption and relationship given by generating elemts of a Cayley graph
I have read a very interesting description of computation related to the RSA group as follows.
"By the Chinese remainder theorem, we have that:
$$(\mathbb{Z}/pq\mathbb{Z})^* \cong (\mathbb{Z}/p\...
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Why modn and modular exponent g^x mod n are not cryptographic hash functions?
I have been trying to find a solution to this question and wasn't able.
When it comes to signatures and Hash Functions, how would be possible to show that $\pmod n$ and modular exponent $g^x \pmod n$ ...
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Finding RSA private exponent with a chosen ciphertext attack?
Let's say there's this blackbox app that has a known modulus $N$, private exponent $e$, and takes ciphertext $C$ encrypted against $N$ and $e$ input and outputs plaintext $M$.
The encryption is done ...
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How to calculate RSA Key Size correctly starting from 384 bits to 15360 bits or beyond 15360 bits
Hello fellow experts here, I am new to cryptography.
Recently I looked into RSA Key Size (Microsoft RSA library), it actually describes that the minimal key length required is 384 bits and maximum ...
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RSA CTF Guidance
There's a great cryptography based ctf site that I've been going through. There's this one question around RSA that has been puzzling me for over a week now.
Please don't tell me the answer, I'm only ...
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Coppersmith's method for small public exponent
Can Coppersmith's method be used to break RSA when we only have access to public key and one ciphertext?
For e.g. suppose we have N and ciphertext c both are 1024-bit numbers and the public exponent e ...
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Common modulus attack with not coprime exponents
lets suppose we have the public keys $(n,e_1)$ and $(n,e_2)$, such that $\gcd(e_1,e_2)=d>1$, and the same message encrypted with these two keys.
I'm trying to see if common modulus attack on RSA ...
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RSA Decryption: Doubts: knowing p or $\phi(n)$ can lead to find private exponent?
I have some doubts about RSA (the public key $n$ and $e$ is public):
Note $n = pq$ and $\phi (n) = (p-1)(q-1)$
1) Say if some hacker knew $p$, why would it be easy for them to find $q, \phi (n), d$?
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Message input format for RSA algorithm
I was trying to implement the RSA algorithm myself. I have written the key generation part. My question is if I have the word "apple" which I want to encrypt, do I have to convert each alphabet to ...
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Binary verification of application image before loading it into DRAM
Working on a boot process where the application image has to be verified before loading it into DRAM.
We found 2 strategies;
RSA-1024, where the private key is secure in premises and the only public ...
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How RSA is implemented by authentication protocols?
I am a beginner in cryptography, i recently learned about RSA algorithm : In short, my understanding for this is :
Sender needs receiver's public key to encrypt the message to a cipher so that only ...
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Why aren't Diffie Hellman public keys used for authentication?
So I have been reading about Diffie Hellman and specifically the MitM attacks that it is vulnerable to.
I am aware that these are solved currently in ssl for instance by using rsa signatures to ...
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RSA algorithm, relationship of the plaintext $m$ with $p$
I am studying the RSA algorithm. If for example the plaintext $m$ has some relationship with prime $p$, let's say $m$ is multiple of $p$ (where $p$ is the $p$ in $n=p \times q$). Can this give an ...
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Does there exist a public database of RSA-2048 moduli and their factors?
Provided some modulus for RSA 2048, is there a way I could look up if
the modulus
and their factors
exists online?
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Size of Key Material of TLS_DHE_RSA_WITH_AES_256_CBC_SHA
What is the size of key material required for generating MAC keys, encryption keys and IV when use TLS_DHE_RSA_WITH_AES_256_CBC_SHA ?
How to calculate it?
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Signing a binary hash vs character representation of the same hash
I have a hash that I want to sign, with the hexadecimal representation: hash_bin=0x11223344 (length 4 bytes).
The same hash also has a character representation hash_text=”11223344”, which is the ...
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Security of ciphersuite and key
Is anyone able to cite resources that can be based on choosing a cipher suite?
In my case, for a VPN server (OpenVPN) I chose a set of ciphers:
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
It provides 128 ...
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RSA - Very big Modulus and Ciphertext
Is there a known weakness in RSA when the value of modulus (n) is very large?
n = 2466 digits
e = 65537
c = 2466 digits
n cannot be factorized. I checked on ...
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How you find the unpadded short plaintext using RSA?
I am currently trying to understand how you find the unpadded short plaintext when you are using RSA. Please help with explaining the process and so I can understand this topic more.
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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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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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How to exchange a secret through untrusted server in two steps?
I have a web application where I control the server, however, it should not have any knowledge of secrets that are exchanged between its users. This server holds RSA public keys of each registered ...
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RSA: Private key given public key, plain text, and cipher text with no padding?
Are there attacks which will return the RSA private key when the attacker knows the public key, plain text, and cipher text when no padding is used in the RSA algorithm? If yes, what are the known ...
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Same message space for different public exponents
What is the weakness, if there is any, of using the same message space for different public exponents (assuming e changes everytime)?
Imagine I have a message space [0,n] where n is a 1024 bit number ...
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Hybrid encryption for MQTT payload?
i've written a simple code for payload encryption, i'v done it with AES-128 CBC mode ,it works fine ,the senario is very simple : the publisher send a JSON payload format that includes the encryption ...
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RSA - Compare two values for encryption exponent, both are relatively prime and $e < λ(n)$
So we have $q = 311$, $p = 163$, $e = 101$, I found $d = 39281$ using Euclidean Algorithm and checked by encrypting and decrypting a message.
Next it is asking if $e = 101$ was a good choice or would ...
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Can an attacker predict value of $d$ if attacker already used $n$ for encryption? [duplicate]
In RSA we have value of n and e which is known to sender.
If the sender keep maintaining a database of possible n's he can easy calculate $\phi(n)$ because he already know $p$ and $q$ then. $d$ is $e^{...
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Coppersmith's method implementation
suppose i have two equations:
$$ (m)^{3} \bmod n = c_{0}$$
$$(m + 2^{k}r + d) \bmod n = c_{1}$$
The values($c_{0}, c_{1}, k, d$) are known.
I wanted to retrieve r (ofc $|r| < n^{\frac{1}{9}})$
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RSA encryption and decryption not resulting to the correct result?
I'm having a hard time creating a functioning RSA algorithm for some reason even though I have all the steps right (or at least I think I do). So I have the following :
I picked prime numbers, $p$ ...
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Simple RSA proof of correctness using Bézout's identity
To show that $m^{ed} \equiv m \pmod{pq}$ with $de \equiv 1 \pmod{\phi(pq)}$ and $p\neq{q}$,
Choose $e$ coprime to $\phi(pq)$ so that $\gcd(e,\phi(pq)) = 1$ and
$$m^{\gcd(e,\phi(pq))} \equiv m \pmod{...
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Confused about final subtraction of modulus in Montgomery Multiplication, during modular exponentiation
I'm confused about how one might supposedly bypass the final subtraction of the modulus in radix-2 montgomery modular multiplication, when used in a modular exponentiation algorithm. The following two ...
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sign data and append certificate VS sign data and certificate
I am currently writing my masters thesis in which I need to develop a licensing module for an application.
The license itself is a JSON Web Token which is signed using a RSA private key.
Since we ...
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Different ways for modular exponentiation $A^E$ with negative A's
I was looking at a way for modular exponentiation $X=A^e \mod{n}$ with negative base $A$ in order to evaluate how it needs to be changed so I can use it with my hardware acceleration unit.
The crypto ...
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Is this schema secure?
I want to know if we use function H as random oracle in RSA Blind Signature and assume that RSA Assumption is correct, is it true that the ...
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Calculate RSA private exponent when given public exponent and the modulus factors using extended euclid
I was reading this answer that shows how to calculate the inverse of public exponent, i got to the point where we apply the euclidean algorithm and finish substituting to get
(40−2×17)−1×(17−2×(40−2×...
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Factoring RSA number knowing some B-smooth numbers
Hi I am studying for an exam and having some problems solving one of the questions. It reads as follows: Factor $$N=44370047$$ using Quadratic Sieve by using the information that you get from squaring ...
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