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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Is it possible to generate a membership proof using an RSA accumulator without knowing all the accumulated values?

I am currently learning about RSA accumulators and this was just a question I had since in most available implementations I see in Github accumulated primes are stored in hash tables and they are ...
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WebCrypto SubtleCrypto RSA sign/verify AND encrypt/decrypt?

I have a project where I'd like to use public-key cryptography in both typical sign/verify situations and encrypt/decrypt situations. For example, I'd like to create a self-signed X.509 certificate ...
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Can a single RSA SecureID device be used for authentication with two different applications of different organizations?

There is a RSA SecureID having PIN + token digits (dynamically changing on device) which is already in use in Company-subsidiary-A whose technology ecosystem is ...
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Looking for a group where multiplicative inverse is hard but calculating multiple pairwise inverses is easy

I have an equation that comes up in trying to do an Attribute Based Encryption scheme, where users have certificates that sign off on attributes that are also watermarked. I perform a division to ...
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What is Stateless blockchain [closed]

I don't exactly the meaning of stateless blockchain. What is the advantage of stateless blockchain? Can someone explain it?
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Brute force integer factorization - back of the envelope calculation

RSA-240, an integer with 240 decimal digits from the original RSA Factoring Challenge, has recently been factorized. According to the researchers, the factorization took a total of 900 core-years on ...
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Nonmembership witness in universal accumulator

We can say that when compared to a Merkle tree, inclusion proofs are constant size by membership witness. Can we say that also for exclusion proof bu nonmembership witness? Is there any advantage of ...
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About the RSA with ASCII [closed]

I have a question about the RSA question is, The ciphertext message produced by the RSA algorithm with key $(83749637, 390625)$ is ...
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Create a ciphertext that decrypt to different plaintexts with different keys in RSA

(This is inspired by this question 1; have also read this question 2 but it's one-time pad) I would like to know, given two message $m_1$ and $m_2$, as well as public keys $(e,n_1)$ and $(e,n_2)$, ...
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How to design a moderated, group for private messages?

I’m trying to figure out how I could create a private group that was P2P yet still allowed someone to moderate members (no public access to messages). I’m assuming standard hybrid encryption (RSA/EC + ...
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RSA signing - does EMSA-PKCS1-v1_5 padding need to be verified?

I am working with an embedded system that accepts firmware updates only if they are validly signed by a particular 2048-bit RSA private key (the embedded system's bootloader knows the corresponding ...
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Help with next step in the Quadratic Sieve

So I am at the same step as someone from math.stackexchange but he never recieved an answer so I will copy-paste his question here: Say, for N = 90283, I compute bound 𝐵=𝑒(12+𝑜(1))(ln(𝑛)ln(ln𝑛√))...
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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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Is encrypting data with AES-CTR-128 and keys with RSA-2048 secure?

Here's a question. I have a file that have to be encrypted with strong cipher (I've choosen AES-CTR-128). I'm using MVC 2019 to compile C++ program. Firstly, I create RSA-2048 key pair (public and ...
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Is the RSA cipher alike to the Shift/Caesar cipher?

I'm sort of a beginner on cryptography so this is probably a really elementary question. I only know the historic ciphers and the general background on cryptography as well as it's general meaning. I'...
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RSA p and q size to encipher a block

I have a plaintext about 18 bit size. I have to encipher it using RSA. How large have to be p and q? So M (message to encipher) = 2**18 bit I tried, using a Python coded RSA alghoritm, different sizes ...
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Secure implementation of public key cryptography

Reading online I've found out that for example the RSA implementation that you usually find on textook is not secure. Where I can find some secure implementation of algorithm such as RSA, ECDH, ECDSA? ...
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Problem with calculating the correct value for $(p-1)*(q-1)$?

I came to a problem when calculating some values for RSA encryption task. So the data I have is this: $e*d=81$ $C=5$ Now I have to calculate the original message($m$) and I have an issue because I ...
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RSA: How to compute plaintexts knowing ciphertexts, public key and relation between plaintexts

I'm trying to solve an exercise where you have to compute two plaintexts $p_1$ and $p_2$, knowing the corresponding ciphertexts $c_1$ and $c_2$ and the public key, of which $e=3$, and $n$ is a large ...
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Using RSA public key as private key and vice-versa

I am writing an application that involves checking to see if data has been created by me. I do this by encrypting the data with the private key on my server, and then decrypting it using the public ...
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Is direct RSA encryption of AES keys secure?

I am wondering: If we take this scheme/procedure and each of it seems very secure (to me at least), is it truly secure or is there a vulnerability hidden in the process? This is the scheme: Bob has ...
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Nonmembership and membership witness in universal accumulator

I am trying to understand cryptographic accumulator and I dont exactly the definition of universal accumulators.I found a definition with its properties in "Universal Accumulators with Efficient ...
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RSA - Compute signature

I have a question in (textbook) RSA. Suppose we have two public keys $pk_1=(e_1,N)$ and $pk_2=(e_2,N)$ (with $\gcd(e_1,e_2) = 1$). Assume that there are $\sigma$,$\sigma'$ such that $\sigma$ and $\...
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RSA: If the least significant bits of the factors are leaked, what advantage is there in factoring N?

For $N=pq$, if the first $x$ least significant bits of both $p$ and $q$ are leaked. what is the advantage in factoring $N$? Does this give an advantage beyond simply lowering the number of bits we ...
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Multiple (RSA) public key encryption how to verify others received the same information? Non-deterministic encryption

I have an RSA system between multiple parties. Alice takes the targets (Bob and Oliver) public keys and encrypts a message using them and sends it to them. All parties know each other's public keys ...
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The GCD strikes back to RSA in 2019 - Good randomness is the only solution?

When someone collects lots of RSA public modulus, the first thing comes to mind is; $$\text{GCD them all}$$ If you calculate the GCD of two different RSA modulus and if the result is not 1 then you ...
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Which padding is used for sha256WithRSAEncryption (1.2.840.113549.1.1.11), deterministic or random?

Questions Is the only way to know which padding was used is to know the context of how sha256WithRSAEncryption was used (that PS is 0xFF when signing, and random non-zero when encrypting)? Is there ...
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Server stored, encypted messaging app

For my personal research, I have to create a messaging app, but security is only important part of application, security from MITM (man in the middle attack), at device end, and at server level. (note:...
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Elliptic Curve vs RSA key length comparison

I'm new to ECC. From this website (GlobalSign Elliptic Curve Cryptography) a 256 elliptic curve key pair provides as much security as a 3072 bit RSA key pair. My question is: how do experts come to ...
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How does RSA encrypt a message? Are the message packets chained together?

This question is quite related to this one, but I am looking for more details. I am writing a very basic implementation to demonstrate how RSA works. My current implementation generates key pairs ...
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How to rotate keys for plaintext in DB encrypted by RSA?

I have encrypted plaintext with an RSA public key. It is stored in a database. This public key will be encrypted by another key with a different encryption algorithm. What does key rotation look like ...
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Finding a pair of exponents so that $c^a \bmod N = c^b \bmod N$

I am not very familiar with RSA, so this question may appear to be stupid. Suppose that in RSA encryption, we are given $c$ (the ciphertext) and $N$ (the semi-prime modulus), can we find a pair of ...
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My RSA decryption doesnt match answer

Break the RSA code whose key is $(n, e) = (8369428283, 1234567)$. Find the deciphering key and then decipher the message under the assumption that the plaintext consists of 7-letter blocks in the ...
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In RSA encryption, can I calculate d given only m,n,c and e? [duplicate]

Newbie here. Not familiar with cryptography; just interested and reading up about it from time to time. We know that the RSA problem (let's say $c=m^e \bmod N, c^d= m \bmod N$) is about recovering $...
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Do I have to know RSA padding scheme in advance when verifying signature with EVP_Verify*?

Is there a way to figure out what RSA padding type was used on signature during verification (when calling EVP_VerifyInit, EVP_VerifyUpdate and EVP_VerifyFinal) or is it a matter of convention which ...
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Modification of RSA using two inverses, one for P mod (Q-1) and one for Q mode (P-1), instead of inverse d mod [(p-1)(q-1)], more or less secure?

Lets say I have the following modified RSA scheme We choose two large primes P, Q, with additional restriction that these are relatively prime to (p-1) and (q-1) We choose N = PQ as public key We ...
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Verify XML digital signature

I'm trying to figure out how to verify an XML digital signature. I have received a signed XML response (in string) in following format: ...
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Is it more weak to encrypt with the private key RSA?

I have a simple question. Is it more weak to encrypt with the private key against the public key with RSA ? Like is it easier to "crack", "brake", "solve", "decrypt" when I encrypt with the private ...
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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: least significant bit position in key

How can I show that $C' = 2^e·C^* \bmod N$ when it is decrypted will add zero bits in the least significant bit position of the key? I am not sure if the cause is multiplying by a ciphertext which ...
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Msieve & Yafu - RSA Exponents and bruteforcing

I am a layman in regards to the math behind RSA (and in general, relatively), and my goal is to bruteforce a large quantity of 512-bit RSA keys. Having searched around, I see that msieve, yafu, and an ...
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Asymmetric or Symmetric encryption

I'm currently looking into OpenSSL and its API and I'm not really familiar with cryptography. So I was looking at the example on asymmetric encryption of an envelope. And it says the message is ...
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Forgery against signature using RSAES-PKCS1-v1_5 padding

I wonder what is the security of RSAES-PKCS1-v1_5 under chosen-plaintext attack, in the context of signature verification. Notations. Let $(N,d)$ be an RSA signing key, and $(N,e)$ the corresponding ...
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How to derive a 4096 bit or 8192 bit RSA private key from a (BIP39) mnemonic seed?

How to derive a 4096 bit or 8192 bit RSA private key from a (BIP39) mnemonic seed? Any tool available for this?
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How is Diffle Hellman with RSA immune to man in the middle?

Alice and Bob want to exchange keys, Alice sends his half (the public key of the ephemeral key pair) signed with his private key and makes the public key available. Eve is bridging the connection so ...
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Appropriate public exponent choice for RSA encryption

From what I understand, we can arbitrarily choose an exponent e as long as $\gcd(e,\phi(n)) =1$. But what is the most appropriate choice for it? Should it be small compared to $\phi(n)$ or approach ...
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Verify if a prime number was accumulated

If a trusted administrator generates RSA accumulator $A$ as: $$ A = g^{x_1 x_2 \cdots x_k} \bmod N $$ where $N=pq$, $p$ and $q$ are both prime numbers and all $x_i$ are also prime numbers. How can a ...
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Requirements for RSA key parameters

Recently I'm working with a chinese vendor for POS devices and their devices use 2048bit RSA keys for signing binaries. I had to generate a public/private pair (so I can sign my own binaries) and I ...
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Is the role of public key/private key determined arbitrarily or mathematically?

I have read about conflicting information about the roles of public/private keys. In one article(Asymmetrical-key algorithms), it says: Simply put each party, say Alice, picks a private random ...
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Not Using RSA In OT1/2 Oblivious Transfer?

I was reading Oblivious Transfer (Wikipedia) and the 1-2 oblivious transfer. I was confused why RSA was needed. Why wouldn't this work?: A:m1, m0 A:x1, x2 -> B B:k, b B:Xb+k -> v -> A A:Xb+k-X1, ...