Questions tagged [public-key]

An asymmetric cipher is an encryption scheme using a pair of keys, one to encrypt and a second to decrypt a message. This way the encrypting key need not be kept secret to ensure a private communication. Similarly in public key authentication, the verification key can be public and the signing key private.

Filter by
Sorted by
Tagged with
2
votes
1answer
66 views

Is Googles Envelope Encryption the same as Hybrid Encryption?

Google is advertising the use of Envelope Encryption in their products with their KMS. By the description, it sounds very much like Hybrid Encryption. But since I could not find any reference to ...
2
votes
1answer
110 views

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 ...
2
votes
1answer
506 views

Public Key generation for Ed25519 vs X25519

It is my understanding that EdDSA uses a slight variant of Curve25519 (typically used for ECDH), called Ed25519. Given the same private key, are the differences between the two algorithms enough to ...
3
votes
1answer
157 views

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 ...
2
votes
3answers
150 views

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 ...
0
votes
0answers
24 views

Efficient receiver determination of public posted cipher

Assume there is a global message board, that people use to send messages to other people. Of course no one else but the receiver should know the content of the message, so senders use asymmetric ...
5
votes
1answer
1k views

Is there asymmetric encryption in SSH?

I've read in DigitalOcean article about SSH that in order for a server to authenticate a client: The server sends the client this encrypted message. If the client actually has the associated ...
0
votes
0answers
27 views

Symmetric key crypto secure communication infrastructure

Imagine that public-key crypto stops working. Are there any academic proposals out there that would explain how we could implement commercially viable secure communication based on the current ...
0
votes
2answers
145 views

Difference between Identity-based encryption and multiple key-pairs of public key encryption?

What is the difference between Identity-based encryption and multiple key-pairs of public key encryption scheme?? Suppose trusted key generator generates a bunch of public and private key pairs $(k_{\...
1
vote
2answers
79 views

Understanding Montgomery's parameterization of elliptic curves

I'm having a bit of trouble understanding the translation of affine coordinates to projective coordinates in Montgomery curve ECM. Would be very thankful if someone could explain it by expanding the ...
5
votes
2answers
877 views

True asymmetric ciphers beside RSA

Is there any TRUE public key cipher beside RSA? Most people would answer Elgamal or ECC, but for what is my understanding (and I know cryptography only superficially), those are not true asymmetric ...
5
votes
3answers
452 views

Why RSA-KEM is more secure than Textbook-RSA?

I am studying RSA-KEM but I can not see why it should be as secure as padding RSA messages (e.g with RSA-OAEP) when exchanging a key between two parties (say A and B). It is easy to see that Textbook-...
2
votes
3answers
3k views

Why do we need a digital signature?

First of all, I want to say that I'm totally new to cryptography. I searched on crypto stackexchange but couldn't find the answer to the following question.(probably because it's easy, but I still don'...
1
vote
0answers
61 views

Safest method for encrypting a file on a local machine

I am looking for a safe method to encrypt a local file on my machine. Let's say I have a file containing my logins and passwords -- how can I make sure that the encryption is reasonably sufficient in ...
0
votes
1answer
123 views

Can we retrieve his private key using his public key in ECC?

A paper wallet is the name given to an obsolete and unsafe method of storing bitcoin which was popular between 2011 and 2016. It works by having a single private key and bitcoin address, being printed ...
1
vote
1answer
134 views

Is it safe to re-use the same p and q to generate a new pair of keys in RSA if the old private key was compromised?

Say I selected two large primes p and q for RSA and computed my public key (e, n=pq) and my ...
0
votes
1answer
111 views

Authenticated encryption using libsodium's crypto_box_curve25519xsalsa20poly1305

It seems that crypto_box_easy, generates a random nonce and appends it to the cipher text in libsodium. I understand using the same nonce with the same key can be ...
11
votes
5answers
3k views

Suppose I capture encrypted data that I want to decrypt. Could I use a server farm to decrypt?

For argument's sake, let's say that I'm a bad actor who produces malware. I've infected around 10,000 computers and smartphones with my malware, which runs in the background and can be used to make ...
0
votes
0answers
40 views

Where to store public key of an asymmetric cryptosystem?

I am developing an application that uses ECIES encryption and I am currently storing private keys in secure place on each peer and storing public keys in a shared database (accessible by all peers). ...
2
votes
3answers
554 views

Why are in asymmetric cryptography as many keys as people involved needed?

The question: "10 friends wish to establish secure communications between themselves using asymmetric-key cryptography. How many keys need to be known by each user?" was posed by my teacher. He says ...
0
votes
0answers
27 views

Will CT (Certificate Transparency) override the use of CAA and/or DANE/TLSA records?

I'd want to know if some of these competing technologies has more chance to survive. It seems they are thought to solve a similar problem by different manners and I'd want to stick to the most ...
1
vote
0answers
46 views

Zero knowledge proof that ElGamal ciphertext encrypts the opening of Pedersen commitment

Given ElGamal ciphertext for a message $m$ with a random $r$ as $(c_1,c_2) \gets (g^r, g^my^r)$ for a public key $y$, and a Pedersen commitment $C \gets g^xh^r$, I have been able to create a proof ...
2
votes
2answers
327 views

RSA exercises example

I have doubts about this question Consider the following textbook RSA example. Let be p = 7, q = 11 and e = 3. Give a general algorithm for calculating d and run such algorithm with the above ...
2
votes
1answer
900 views

Database and End-to-End Encryption

I'm currently designing a mobile/desktop application to synchronize some messages or notes. I'm searching for a way to secure it and to avoid letting the server be able to read the messages. My goal ...
2
votes
4answers
660 views

Why use symmetric encryption with Public Key?

A. From what I heard (and I am beginner at a security/cryptography), if you have a payload that is very large, asymmetric is a no-go. B. Also, if you do have secret symmetric (e.g. AES) keys, you ...
0
votes
0answers
25 views

What is the current state of the Conjugacy Search Problem in Matrix and Permutation Groups?

It results that I have come with a mathematical approach to solve the CSP (Conjugacy Search Problem) where the platform group $G$ is either a permutation group or a Matrix Group. From my part I ...
9
votes
1answer
8k views

Can an RSA private key have several public keys?

Ok, so my cryptography lecturer in University posed this question at the end of the RSA key generation lecture as a brain teaser. I have been thinking about this and I think I have come up with a way ...
22
votes
5answers
24k views

Why is it important that phi(n) is kept a secret, in RSA?

Why is it important that $\phi(n)$ is kept a secret, in RSA?
-1
votes
1answer
65 views

I am new to digital certificate 509V3 concept. can some one please clarify the below points [closed]

I am using RSA 2048 with SHA 256 primitive in certificate: How to verify the user certificate n + 1 with Root certificate n? why it is required to perform Certificate chain verification? How to ...
0
votes
1answer
385 views

PKCS1 v 1.5 Signature questions

I'm crash studying the public key cryptography topic and I have a few questions about how signatures are created. So are digital signatures just encrypted hashes? If that's the case then I can hash ...
0
votes
2answers
219 views

Digital signatures with one-way function, can messages be longer than the signature?

Ethereum and Bitcoin both use 512 bit signatures, can the message that is being signed be longer than 512 bit?
0
votes
1answer
1k views

How is public key cryptography used for digital signature?

In public key cryptography, there are two different keys used for the encryption and decryption of data . I am wondering how it is used for digital signature
13
votes
1answer
9k views

How can one validate with a public key a JWT signature generated with a private key?

As I understand it, a JSON Web Token (JWT) consists of 3 parts: the header, specifying the hashing algorithm to use for the signature; the payload itself; and the signature, which is a hash of the ...
1
vote
1answer
97 views

Digital signature

I learned that a digital signature is encrypted using private key and is decrypted using public key. How does the verifier gets the public for verifying the signature? If a person has to request ...
0
votes
1answer
764 views

RSA-OAEP Padding scheme

Honestly I'm really confused about padding in RSA scheme. I don't study computer science, and I'm a beginner learning cryptography (self-taught). Can anyone give me suggestions?
3
votes
1answer
91 views

Is there another group structure that is suitable for RSA other than $U_{pq}$?

I know that calculating the cardinality of $U_{pq}$ is infeasible and therefore it is extremely hard to break a code using Lagrange's theorem. But later on my studies i realized main principle of RSA ...
2
votes
1answer
134 views

Chosen Plaintext Attack and Chosen Multiple-Plaintext Attack

The original CPA game: The adversary gives two arbitrary messages $m_0$ and $m_1$ to a challenger; The challenger encrypts an arbitrary message $m_u$, $u∈\{0,1\}$ , and sends the ciphertext to the ...
1
vote
2answers
130 views

How does this formula work $(aG + bG) = (a + b) G$ in ECDSA?

Please explain how does this formula $(aG + bG) = (a + b) G$ work in ECDSA? According to the source: $a$ and $b$ are different private keys Suppose $a = 3$ $b = 4$ then the public key is $Q = aG$...
0
votes
1answer
65 views

What's the proper way of fitting hash digest to encryption scheme?

I would like to know what is the proper way of fitting the hash digest to the prime in which the encryption scheme operates. regardless if the bits of the hash digest is larger or smaller than the ...
1
vote
1answer
42 views

Is it possible to execute elliptic curve encryption on small sensor-tags CC2650?

I am working on a project wherein ECC needs to be implemented on small devices, namely, CC2650 sensor-tags for authentication. The ECC implementation should be on Contiki OS. I have read some articles ...
0
votes
1answer
263 views

Is there a feasible way to generate an RSA key manually the same way as it is for an ECC one?

In elliptic curves, a private key is just a random number, and one relatively small compared to other crypto systems (256 bits for ECC vs 4096 bits for RSA for example). Suppose I don't trust ...
0
votes
1answer
58 views

Is it possible to construct dataset for only another party to consult?

Is it possible to construct a dataset made of some kind of probabilistic encrypted indexes such that anyone can update the information contained in the set but only the one with a secret key could be ...
2
votes
1answer
111 views

Paillier Private $\mu$ and $\lambda$

The Paillier CryptoSystem has a public key that $(g,n)$ and the private key which can be exclusive to $\lambda$, where the decryption scheme is: $m = L(c^\lambda \bmod n^2)/L(g^\lambda \bmod n^2) \...
2
votes
1answer
231 views

What happens when i sign a public key with its private key pair?

I am not a cryptologist, just a cryptography user, so not sure if this is safe. I want to sign a public key with its private key pair. Is it dangerous to share this signature result along with ...
12
votes
3answers
6k views

Why are asymmetric cryptography keys more vulnerable to brute force attack than symmetric ones?

I came across this paper which says that Asymmetric keys must be many times longer than keys in secret-cryptography in order to boast equivalent security. Keys in asymmetric cryptography are ...
1
vote
1answer
82 views

RSA figuring out the recipient of a ciphertext

I have this question I am trying to figure out the answer about RSA. I'd be grateful if someone could actually help me understand how the procedure would work. I am new to cryptography and with all ...
2
votes
0answers
25 views

What are some examples of out of bound channels that work over the Internet in practice?

If I want to verify a public key (be it RSA, PGP, etc.) with another client over the Internet only, what are some viable out-of-bound channels for verification? Which channels have been used in ...
0
votes
1answer
162 views

Hashing using asymmetric cryptography

Every now and then, we read that some hashing function has been weakened or broken, but we almost never hear this for asymmetric cryptosystems like RSA or ECC. That's because while asymmetric ...
1
vote
1answer
65 views

Is it possible to calculate the random factor $r$ from a encrypted message and the private key in a Paillier cryptosystem?

I have already done my research and found various sources that state that it is possible but there are also a lot of them that says it is not possible to recover $r$. This Q/A on this site for example ...
1
vote
1answer
38 views

What happens after sharing the secret key in quantum cryptographic schemes to send the message bits?

As a person working on the physics perspective of quantum communication, I understand the process upto which the quantum key is shared securely. What happens after this process to send message bits? ...

1
3 4
5
6 7
34