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.

Filter by
Sorted by
Tagged with
1
vote
1answer
46 views

Licensing software with asymmetric signed files

NOTE: I know that there are numerous topics here on StackExchange about this but I've read them all and this question still persists. I'm currently working to enhance the security of a windows based ...
0
votes
1answer
32 views

What algorithm for AES key wrapping to choose in an embedded environment

In an embedded environment, what AES key wrap algorithm is best, in terms of performance and security coverage? We are using RSA PKI asymmetric encryption.
2
votes
1answer
130 views

Using YubiKey to store a PIN-protected secret for disk encryption

I want to store a secret on YubiKey and use it for disk encryption. It's crucial that it be PIN protected. There are a limited number of PIN tries, and after three attempts the YubiKey would be ...
1
vote
1answer
24 views

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 ...
2
votes
1answer
223 views

Secure multi-party computation for digital signature

Is there any practical algorithm that will allow to use public key cryptography (RSA or ECC) in the following way There are N parties. Up to M are malicious adversaries (were trusted, but got taken ...
2
votes
1answer
71 views

Why is there no “ephemeral non-DH EC” key exchange in TLS?

In RSA key exchange, the client picks a premaster secret and encrypts it with the RSA public key in the server certificate, and sends it to the server. This offers no forward secrecy. In ECDHE key ...
1
vote
1answer
46 views

number theory question in a group with unknown order

I was reading a paper and I am struggling understanding one part of it. Lets say we have a group $G$ of an unknown order $n$. we know that $B<n<B+C$. both B and C are large values). we choose a ...
1
vote
1answer
61 views

Is there an asymetric encryption whos output size is quite equal to the input size

I want to verify, that a chunk of data which has a size of around 16 bytes is sent by me, by simply encrypting it via a private rsa key, providing the public key in the source code for the ...
1
vote
2answers
130 views

Why can't ransomware practically use RSA to encrypt all files?

I understand that a few ransomware have used an RSA public key to encrypt all files belonging to the victim. This is a bullet-proof system in terms of its security because the private key is always ...
3
votes
3answers
4k views

RSA: Is it secure to use the private key to encrypt and the public key to decrypt?

This may sound weird: What if I don't let others know my public key, then use my private key to encrypt, and the public key to decrypt? Is this secure? Let me explain a little bit: Common usuage: use ...
0
votes
2answers
63 views

A number theory problem in RSA

Let say we have $N=pq$ (Both $p$ and $q$ are safe primes, meaning $\gcd(p-1,q-1)=2$) let's assume $e$ is an odd number which can be efficiently factored and assume that we know the $e$'th root of 1 ...
10
votes
4answers
8k views

Why do we need Euler's totient function $\varphi(N)$ in RSA?

After we calculated $N = p * q$, we calculate $\varphi(N)$ and use it later to determine $e$ (PR) and $d$ (PU). But why? For decryption and encryption we only use $N$ and don't need $\varphi(N)$. So ...
0
votes
0answers
8 views

Openssl : Is it possible to disable RSA blinding? [migrated]

Basically I am trying to compare versions of openssl, regarding timing attacks. But is it possible to disable RSA blinding in any given version of Openssl (new versions)? I implemented everything in ...
2
votes
1answer
174 views

Information security evaluation

I saw this exercise for evaluating the security(confidentiality, integrity, authenticity, and non-repudiation) of some schemes: ENC(M) || SignA(ENC(M)) ...
1
vote
1answer
45 views

RSA Signing: SHA512 incompatible with PSS?

I am wrapping the RSACng class from the .Net API. Whilst unit testing, I run checks against an array of possibilities: Key Size = 1024, 2048, or 3072 bits Padding ...
1
vote
1answer
25 views

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 ...
4
votes
1answer
67 views

What is the Bilinear-map accumulator disadvantage

Bilinear-map accumulator [1] is more efficient than the RSA accumulator [2] but do you know any disadvantage for the bilinear-map accumulator when compared to RSA accumulator?
1
vote
2answers
93 views

SHA-3 for Integrity

We used to use CRCs to check the integrity of files. For safety analysis we could associate a probability for detecting a corrupted bit in a large file. Now we are using an RSA Signed SHA-3 hash for ...
3
votes
1answer
72 views

Can a 3rd party decrypt static Diffie Hellman?

Do cipher suites that use static Diffie Hellman (not Ephemeral) allow for the same 3rd party decryption ability as RSA cipher suites? With RSA key exchange, 3rd parties can gain possession of the ...
3
votes
1answer
107 views

RSA Accumulators with auxiliary information or known trapdoor information

In "Universal Accumulators with Efficient Nonmembership Proofs" by Jiangtao Li1, Ninghui Li2, and Rui Xue3 section "How to compute witness with the auxiliary information" the authors write: "The ...
31
votes
6answers
6k views

Is it feasible to build an index of prime factors?

Would it be possible to break an RSA key, in for example 1 week of time, if the cracker have already spent X number of years building an index of primes by performing every permutation of existing ...
0
votes
0answers
24 views

SubtleCrypto.wrapKey usage: can exportKey but not wrapKey? [migrated]

I'm trying to wrap an RSA private key using an AES-256 key-wrapping key, using the SubtleCrypto API. I've managed to make the RSA keys and key-wrapping AES key (plus another symmetric AES key) using <...
4
votes
1answer
144 views

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 $(e,n_2)$, ...
0
votes
1answer
86 views

Exponentiating big numbers for RSA operation

I am following the book "Network security private communication in a public world - 2nd edition. Section 6.3.4.1 Exponentiating big numbers. base = 123, exponent = 54, mod = 678 What I understand is ...
8
votes
1answer
169 views

Can we break RSA with an optical Fourier Transform?

We all known that RSA can be compromised using quantum Shor's algorithm. The horsepower underlying this algorithm is the Fourier transform. However, we can use alternatives to perform this function, ...
1
vote
1answer
131 views

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 ...
31
votes
0answers
1k views

Who first published the interest of more than two prime factors in RSA?

Multi-prime RSA is now a well known technique (described here): it uses $k>2$ distinct secret prime factors in the public RSA modulus, with the advantage that, using the CRT, we can gain a speed ...
4
votes
3answers
735 views

Recommended key size for DKIM

What is the recommended key length for DKIM? I'm currently thinking about a 1024-bit key vs. a 2048-bit one. From the crypto point of view for RSA, 2048 or 4096 bits is clearly recommended--no ...
-2
votes
1answer
5k views

crack RSA encryption

According to Wikipedia RSA definitions are : so we have $n$ and $e$ because $p$ and $q$ are prime so there is only one $p$ & $q$ which fit to n so from n we can have $p$ and $q$ so we have $\phi(...
0
votes
1answer
140 views

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.
0
votes
0answers
35 views

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 ...
5
votes
4answers
2k views

Choosing which is public vs private key

When I calculate two RSA keys, what if anything, would make any difference which I call the public vs which I call the private key?
2
votes
0answers
64 views

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 ...
1
vote
0answers
60 views

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 ...
0
votes
0answers
19 views

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 ...
0
votes
0answers
54 views

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 ...
1
vote
1answer
61 views

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 ...
1
vote
1answer
27 views

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 ...
2
votes
1answer
3k views

How to create a PEM file for storing an RSA key?

I have an RSA private key $\{d,n\}$ and a public key $\{e,n\}$, where $n$ is the modulus, and I also have the prime factors $p$ and $q$ of $n$. I want to create a PEM file containing this information,...
2
votes
1answer
93 views

Can Paillier ,RSA or any other schemes be used for universal re-encryption like elGamal?

ElGamal, RSA, and Paillier cryptosystem have homomorphic property, and can be used fro re-encryption purposes. I want to use the encryption to re-encrypt ciphertext(as in proxy re-encryption but ...
1
vote
0answers
22 views

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 + ...
1
vote
0answers
23 views

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√))...
1
vote
3answers
174 views

Negotiate a secure connection without certificates?

I would like to have a simple experience for a user for setting up a secure connection between two computers against a MITM attack. Something like the following: A number (possibly base64) appears ...
30
votes
4answers
7k views

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 ...
1
vote
3answers
983 views

two public keys with same passphrase insecure? | can two hashes be compared?

Suppose someone had generated a 2.048-Bit RSA GPG/PGP key pair and published the public key on the usual key servers. Then he withdraws this key and generates a new one in 4.096-Bit RSA using the same ...
4
votes
2answers
4k views

Openssl & RSA : how many public exponents are possible?

I would like to know if it is possible to set the public exponent we want with "OpenSSL RSA" or if it is really limited to 2 possible exponents: 3 65537 If yes, why ?
8
votes
1answer
806 views

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 ...
1
vote
1answer
167 views

Large Volumes of Asymmetric Encryption

First of all, I apologize in advance if I use any incorrect terminology. I am just getting my feet wet when it comes to cryptography and there is a lot to learn. For the past 12 months, we have been ...
3
votes
2answers
118 views

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'...
0
votes
0answers
37 views

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 ...

1 2 3 4 5 40