Questions tagged [elliptic-curves]

Elliptic curves are algebraic-geometric structures with applications in cryptography. Such a curve consists of the set of solutions to a cubic equation over a finite field equipped with a group operation. Questions relating to elliptic curves and derived algorithms should use this tag and might also consider more specific tags such as discrete-logarithm and ecdsa.

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Can two different hash function create two unlinkable ed25519 keys from the same randomness?

Assume the following scenario: Alice has access to 32 bytes of true randomness $s$. Alice hashes $s$ with SHA-512, and uses the resulting hash as the secret $d_{A}$ for ...
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Help breaking ECDSA with biased nonces

I am currently trying to do the cryptopals challenge 62, breaking ECDSA with biased nonces, with the help of those two links (1 2) that describe accurately the attack. However, after around 15 hours, ...
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EC implementation on Edward curves : what modulo is used in implementation?

I'm trying to implement EC scalar multiplication in the fastest way possible (but still with a good curve) on a GPU. I'm specifically looking to implement it based on https://github.com/Chair-for-...
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Is it possible to generate ECDSA signature without nonce?

I am newbie to cryptography and my college has given me this ECDSA. I know that you have to divide result of: h(m)+r.priv in order to generate signature. But is it possible to generate signature ...
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extracting a public key from an Ed25519 private key with OpenSSL? [migrated]

Ed25519 private keys can be generated by doing openssl genpkey -algorithm ed25519 -outform PEM -out private.pem. My question is... using OpenSSL is there a way to ...
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Is using a cofactor to find a base point only for performance reasons?

For elliptic curve cryptography, the procedure to find a base point that generates a subgroup with order $n$ is: Calculate the order $N$ of the elliptic curve (using Schoof's) Choose $n$. $n$ must be ...
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Are there any public keys for which the private key can be easily derived (ECDSA)?

I know that generally it's infeasible to find the private for any given public key. But I also came across the question "Find ECDSA PrivKey to PubKey = 0", in which it was explained that the ...
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Can I know from a Bitcoin public key if the private key is odd or even?

Can I know just from a Bitcoin public key if the private key is odd or even? [moderator note] That is, can we find parity of the private key from a secp256k1 public key?For the original dump of ...
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running Project Wycheproof against crypto implementations in languages other than Java

So I guess https://github.com/google/wycheproof "tests crypto libraries against known attacks". It appears to mainly be intended for Java crypto providers but can it easily be adapted to be ...
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What is/was SEC#1 ECC public key leading octet 0x01 for?

In the SEC#1 elliptic curve cryptography standard, the encoding of the public key involve a leading octet: 00h: The public key is the point at infinity. 02h, 03h: The public key is the compressed ...
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Why does ECDSA produce a pair of values in its' signature (r,s)?

I was wondering why ecdsa generates a signature in form of a pair (r and s) and why it can't be only one value.