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.

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[MS-WCCE]: Windows Client Certificate Enrollment Protocol - Null Signature

MS ADCS is using Windows Client Certificate Enrollment Protocol for issuing and renewing certificates. In the [MS-WCCE]: Windows Client Certificate Enrollment Protocol document, there is a chapter 2.2....
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Is it possible to use Diffie-Hellman protocol for symmetric group?

I was asked this question during one of my first cryptography classes, and I'm not sure if I understand it correctly. To begin, I know that after using the Diffie-Hellman protocol (which itself is ...
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Key Exhaustion Risks in Symmetric and Asymmetric Cryptography

For the symetric keys it is recommend that the same key should not be used to encrypt large number(2^32) of cipher blocks to avoid the key-exhaustion risk. Curious to know whether the asymmetric key ...
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Is it possible to homomorphically evaluate an encryption circuit?

I know that it is possible to homomorphically evaluate a decryption circuit as it is the main idea behind bootstrapping, but I was wondering if it was possible to evaluate an encryption circuit ...
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Why I need to pass Secure Random when I am loading the key from PKCS8 format [migrated]

I am using Ring lib in Rust to generate ECDSA_P256 and I am passing SystemRandom, and I am getting PKCS8 key pair format. Until ...
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Sending public key trough untrusted server

I am developing end-to-end encrypted chat system (which is open-source). When I want to give other client my public key, I need to send it trough server, right? I want to make sure no one can edit the ...
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How to know if an ECC public key is y or -y

I'm a beginner still learning how ecc works... And i think I understand that in secp256k1 public keys there is something called addictive and negative inverse for example private key:- ...
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Can you sign messages using Wireguard's keys?

I was wondering if I could use Wireguard's keys to sign messages, and prove authenticity of a node that runs Wireguard with its known public key from other nodes, so that I can use it in a system to ...
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Is it possible to generate an elliptic curve (with the hard discrete logarithm problem) by iterating only a finite field, but not its $j$-invariant?

Let me ask one question. Maybe, you know an answer. Thanks in advance for any response. Let's fix an elliptic curve $E$ over the field $\mathbb{Q}$ of rationals without complex multiplication, i.e., ...
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Obfuscation scheme wanted

I'd like to know if there's any cryptographic scheme that implements something similar to what I'm summarizing here below. Thanks a lot for reading and for any hint or question. Intro-Scenery: There's ...
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Does Qrypt's BLAST protocol based on "Doubly-Affine Extractors" use public-key or symmetric-key cryptography?

The company Qrypt states that "Key distribution based on asymmetric algorithms is a weak link for cryptography" and claims to "enable encryption without distributing encryption keys&...
Very Tiny Brain's user avatar
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Is concatenation of secure encryptions secure?

If I have $n$ secure assymetric encryption schemes, is their concatenation $Enc_{k_1,...,k_n}(m)=Enc_{k_1}(m)||...||Enc_{k_n}(m)$ secure? My intuition is that the concatenation is secure, but I can't ...
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What can I use for encrypting by one key, decrypting by another key?

I have case when I need take payload to client with key for decrypting. But client mustn't encrypt another payload by this key. After some research, as I understand it's case of asymmetric encryption. ...
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Using HPKE, if I generate my key pair can I derive the public key from the private key just in case I lose the public key?

Hypothetically, if I am using tink-java and I generate a keyset/keypair. If I lost my public key, can I get the public key from the private key?
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The proof of Claim 5.2 in the "On Lattices, Learning with Errors, Random Linear Codes, and Cryptography"

When I'm reading this paper "On lattices, learning with errors, random linear codes, and cryptography" by O. Regev. I have trouble understanding the proof of claim 5.2. "Hence, it is ...
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in MA-ABE, what is the diference when prove a scheme is selective or static?

I have read [1]Decentralized Multi-authority ABE for NC1 from BDH, [2]Decentralizing Attribute-Based Encryption, [3]Fully Adaptive Decentralized Multi-Authority ABE, When I compare security proof in [...
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Is there any cryptography-based assured data deletion technique currently as a standard?

I've recently read part of a book exploring secure data deletion techniques for many storage mediums. In particular, I read about assured data deletion techniques developed for data outsourced to the ...
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Signature Chains: Ensuring Authenticity and Trust

I'm studying for an exam and came across this question: When an electronic signature of a message claimed to be produced by Alice is verified we typically verify (at least the first time): that the ...
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Clarifying terms for cipher, algorithm, rsa, asymmetric, openssl

I am a self taught front-end developer and I am just trying to get my cryptography terminologies straight. I will make some statements. Can someone correct my mistakes? Question 1 I read that cipher ...
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Devising a system that allows for aggregate computations but does not hold the single values

First of all apologies if this is not the right place. I am not very knowledgeable in cryptography but I thought you can at least point me in the right direction of research. The following is a toy ...
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The weakening of PQC as a result of lack of KEX?

As far as I can tell we don't have any good key exchange post-quantum candidates. SIKE was broken some time ago. It is possible to reach an authenticated shared secret by having the public key holder ...
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In Bitcoin, given half the 52-character private key in WIF format, is it possible to reconstruct the whole private key?

Given the following two preconditions: It is almost impossible to reconstruct a bitcoin private key if an attacker only has one half of the private key as well as the public key. It is almost ...
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P256 signature verification was succeed with 2 public key [duplicate]

I tried to recover public key from P256 signature. With 2 recovery id ( 0, 1 ), signature makes 2 public key. And I tried to verify signature with public key and verification was succeed all of 2 keys....
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Not understanding elliptic curve scalar multiplication to produce Ethereum address

This is the equation Public key = Private key * G Here, ...
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How does the security of RSA compare to a symmetric cipher when both public and private keys are secret?

When RSA is used in a fashion where both the private key and the public key are both secret (for example, when the public key in a KEM is never leaked) could RSA be then evaluated as a symmetric ...
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Given and encrypted message, is it theoretically possible to decrypt a message without the key or guessing it? If so, what methods could be used?

Decrypting an AES-Encrypted Message Without the Key: A Cryptographic Challenge Summary: I am investigating the possibility of decrypting an AES-encrypted message when the encryption key is unknown ...
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Keygen with timelock encryption so that the secret key is hidden from everyone?

I'm wondering if the following scheme (or something similar) can exist: I want to encrypt a randomly generate a public key and secret key pair, $(pk, sk)$. I would like that $sk$ is encrypted some ...
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In Symmetric encryption where Alice and Bob message each other, how can both decrypt the same data?

I first posted this question on StackOverflow but they told me it belongs here instead: https://stackoverflow.com/questions/77856486/in-symmetric-encryption-where-alice-and-bob-message-each-other-how-...
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RSA signatures without padding by using XOF output in range [1, n-1]

RSA signatures are implemented by encrypting the padded hash with the private key. Why not take the approach RSA-KEM is using by removing the padding entirely and replacing the hash with a XOF that ...
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Semantically secure public-key encryption scheme

Suppose that $(\mathrm{Gen},\mathrm{Dec},\mathrm{Enc})$ is a semantically secure public-key encryption scheme. I define $E' = (E(e,m)\oplus m)\parallel (E(e,m)\oplus e)$. Clearly, this is now not ...
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Ephemeral ECC refresh vs. simple hash ratchet

Some protocols employ ephemeral ECC key exchanges throughout the session. Such as the Noise framework. Is the rationale to do this simply because you can do it efficiently? To provide future secrecy ...
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Loop back or cyclic nature of secp256k1 curve

I am working with point addition and scalar multiplication on the secp256k1 curve for points $(x,y)$ or public keys to derive the next public key scalar k times further from it. Actually when I use a ...
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Are RSA signatures distinguishable from random data?

In the spirit of Are curve secp256k1 ECDSA signatures distinguishable from random data? Are RSA signatures distinguishable from random data? What if you don't know the message? What if you have many ...
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Security proof of this paper(Ciphertext-Policy Attribute-Based Encryption) which proposes the first CP-ABE scheme

I have trouble in understanding the security proof of this paper(Ciphertext-Policy Attribute-Based Encryption) why are these two hybrids equivalent to the modified game above? It is obvious that $...
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Compute a proof for a verifiable delay function

I am trying to solve the following problem: Alice generates a RSA key $(n, \phi)$, she shares with Bob the value $n$, and $y = g^{2^{t}}\;\text{mod}\; n$ for $g$ a generator of the group $\left(\...
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Non-prime value chosen for u in DGK encryption

In DGK encryption, one of the parameters of public key is value u where it is a small prime with minimum length l+2. It is not obvious for me what is the security compromise if u is not prime. Any ...
Fattaneh's user avatar
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CCA security problem

Let $(\mathsf{Gen}, E, D)$ be a CCA-secure public key encryption system with a message space $\{0,1\}^{128}$. Is the following derived cipher $(\mathsf{Gen}, E', D')$ also CCA-secure? Justify your ...
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Finding plain text given two cypher texts of the same plain text with two diffrent public keys

I want to find the plain text from two cyphertexts of RSA, encrypted with two diffrent public keys. I know that: for E((n,e),m) = c0 and E((n,f),m) = c1 , c0^x . c1^y mod n = m mod n = m (ex + fy=1) ...
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RSA key generation with large random numbers and no primality testing

Does the security of RSA rest entirely on the modulus having at least 2 large random primes? Suppose you were to generate 2 random 1,000,000-bit numbers and just use the product of those as the ...
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1 answer
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Difference between a a doubled point and a point from point addition

Are all doubled points on an elliptic curve even, meaning if you compress the point, it will have '02' plus the $x$ coordinate? If not, what distinguishes a doubled point from a point resulting from ...
Dev Tenji's user avatar
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Cannot get RSA encrypt and decrypt to work in hardware and online calculator

I am attempting to get a hardware implementation of RSA working but I am having trouble with encryption and decryption. First, I ran these commands to generate the keys: openssl genrsa -out private-...
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Possible to encrypt message without knowing recipient public key?

Assume Bob is sender and Alice is future recipient. In ideal situation Bob know Alice public key, and encrypt message with it. But what if Bob don't know Alice public key (he only will know Alice ...
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which DH protocol is safer in communication with given condition?

I am trying to understand some concepts such as DH problem and its variants. I have the following question from the book I read. (note that I translated the question from my language to english) ...
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5 votes
1 answer
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Integrating Elligator mapping with libsodium Curve25519 implementation

I'm currently working on a project where I want to map Curve25519 public keys to uniformly random noise. The main idea is that when these transformed public keys are sent over a network, an outsider ...
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What scheme is the best for combining two shared secrets?

I'm developing a program that uses a hybrid Key Encapsulation Mechanism (KEM) scheme, employing Kyber and X25519, with each producing a 32-byte shared secret. What would be the best scheme to combine ...
Zola Gonano's user avatar
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2 answers
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What happens if we know that for an RSA key pair, the equation $d^e \equiv c \pmod{n}$ holds?

If we possess the knowledge that the expression $d^e \equiv c \pmod{n}$ holds for an RSA key pair, what would be the implication or consequence of this? Here, $e$, $n$, and $d$ represent the public ...
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Is it safe to derive a secret from a signature?

Many blockchain users have wallets that hold a private key, which can interact with a website. For example, the website can request the wallet to sign a specific message. 'Do only sign this message if ...
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I'm wondering if using the same one public key does not guarantee privacy in the computation of multiple data owners

Participating entity: multiple data owners, computing clouds Protocol: The multiple data owners send their data to the computing clouds, which perform the computation of the data. Privacy protection:...
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Are high-dimensional versions of NTRU cryptosystem more secure?

The basis for this question is a 1-dimensional NTRU cryptosystem. After some literature inspection I have found out it can be also generalised into higher algebras: quaternions (QTRU) and octonions (...
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Does ECC give the most secure assymetric cipher for a given public key size?

Cracking an ideal block cipher is basically a brute force key enumeration. The complexity of the attack is exponential, growing as $2^b$. Cracking ECC is also exponential, but the cost grows as $2^{\...
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