# Questions tagged [secp256k1]

This tag should be used for anything related to the secp256k1 algorithm used for Bitcoin's public key cryptography.

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### Subtraction of inverse points in secp256k1

In pure math given: k = 10 l = -10 k + l = 0 k - l = 20 Now in secp256k1 $K = k*G$ $L = l*G$ $K+L = O$ $K-L = O$ Why do we get identity point on subtraction since: ...
• 13
1 vote
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### Secp256k1 giving y-value for inverse of point

Given a secp256k1 point $P$ with scalar 3 where: $P = 3*G$ You get a point with co-ordinates: ...
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### What's wrong with BIP32 from NIST's perspective?

BIP32 is listed as Non-Approved Security Functions (see page 29 in 1). I could not find any problem with the primitives used in BIP32. HMAC-SHA512: This is a FIPS-approved algorithm (see page 25 in 1)....
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1 vote
47 views

### Can the ability to sign arbitrary messages expose the private key?

Consider a system that consists of a black box (some abstraction layer with perfect sandboxing). The black box contains a private key that cannot be extracted by request, but the black box exposes an ...
1 vote
149 views

### What’s the fastest known Koblitz curve addition law for FPGA that maximizes the per-LUT throughput?

The addition or multiplication laws used by large mainstream libraries achieve faster speed by using many many more operations in order to avoid larger numbers. And my problem is here: faster speeds ...
• 196
1 vote
117 views

### Is it safe to reuse the same scalar when doing direct scalar multiplication on Koblitz curves?

Let $s$ be a private key and $k=intAsScalar(s)$. Finding $s$ from $P_k=[k]G$ involves solving the Elliptic curves discrete logarithm problem. But what if the same $k$ is also used for performing 1 or ...
• 196
1 vote
56 views

### The comparison of public keys corresponding to signatures based on secp256k1

Can two signatures based on the elliptic curve secp256k1 be compared to determine if they use the same public key without recovering the public keys?
171 views

### can we modify the prime field by increasing it in secp256k1?

If in ECDSA secp256k1 we have the prime field p=2256 - 232 - 29 - 28 - 27 - 26 - 24 - 1, can we increase it to p=2256, if we keep the double and add operations the same, the curve equation the same ...
1 vote
97 views

### How to use smt solvers in order to restrict the possible key search where a portion of the private key and a portion of the public key hash is known?

I’m in the following situation : I’ve a portion/first bytes of a private secp256k1 security key such as it would take minutes to fully recover it through Pollard’s Kangaroo if I had the public key. ...
• 196
1k views

### When incrementing a private key by 1, by how much is the public key Incremented?

If you have a secp256k1 keypair and you increment the private key by 1, then a faster way to compute the new public key is to perform an addition on the previous public key. But by how much? Some ...
• 196
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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:- ...
1 vote
46 views

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### Help with adding and multiplying points on secp256k1

I'm currently working on implementing digital signatures on the curve secp256k1 (for learning purposes only), and I'm having some trouble implementing ECDSA on curve secp256k1. As I understand it, ...
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268 views

### What is secp256k1 and can we have a post quantum cryptography with that? [closed]

Please detail secp256k1 and its role in a public key cryptography. Please explain can we use it into a post-quantum cryptography and how can we do it?
• 109
1 vote
669 views

### ECDSA SECP256k1 curve - same-r-value-is-used-for-two-different-addresses

Edited: changing the notation according request by fgrieu. I have prepared 4 transactions for 2 pubkeys with the same r1 and r2. properties of secp256k1: ...
• 11
1 vote
54 views

### Can a quantum attacker prove that incomplete ECDSA signatures were produced with the same key?

Assume a 256-bit ECDSA private key used with Secp256k1 and SHA-256. This key signs multiple different messages in a fully deterministic manner as described in RFC-6979, so signing the same message ...
• 43
190 views

### Given multiple incomplete ECDSA signatures, what can a quantum attacker learn in the following scenarios?

Assume a 256-bit ECDSA private key used with Secp256k1 and SHA-256. This key signs multiple different messages in a fully deterministic manner as described in RFC-6979, so signing the same message ...
• 43
41 views

### Fusion auth versus jose4j library for jwt using secp256k [closed]

I am a beginner in-terms of JWT libraries in programming. How the keypair used (secp256k1) is related with the algorithmic header used for creation of JWT? And why authfusion doesn't need an ...
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157 views

### Elliptic Curve - Is it possible to know whether a particular value is the result of ECadd or ECdouble?

As we know the public key is generated from the private key and the process is point addition and point double and so on. If we see a list, it would look like a list of values coming from ECadd and ...
476 views

### Criteria for choice of prime field in secp256k1?

In secp256k1, the prime order field $\mathbb F_p$ uses $$p=2^{256}-2^{32}-977$$ This is the largest prime $p$ less than $2^{256}-2^{32}$ allowing to construct a Koblitz curve $y^2\equiv x^3+b\bmod p$ ...
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1 vote