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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In God We Trust and Faith in Cryptocurrency [closed]

Currency currently has "In God We Trust" written on it. Has faith in God been replaced with faith in Cryptocurrency? Or more directly, faith in the cryptographic primitives used to "...
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How to verify a lnurl-auth callback with python

I want to create a Python implementation of an lnurl-auth server. I started a quick HTTP server to be the callback url, and captured the signed callback sent by BLW on Android. ?tag=login &k1=...
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What is the difference between secp256k1_ecmult_gen and secp256k1_ecmult?

libsecp256k1 has two implementations, secp256k1_ecmult in ecmult.h and secp256k1_ecmult_gen in ecmult_gen.h, to multiply the points of an elliptic curve. secp256k1_ecmult_gen supports simple ...
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What is the math behind Bitcoin's elliptic curve?

I have seen many videos regarding the math behind the bitcoin elliptical curve but none of them show the public key generation. They are just defining few steps. I need the complete math behind the ...
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51 views

need help generate single publickey on cuda device

I am trying to generate a public key from a hash on a cuda device. I couldn't find a ready source for that task. So I want to try to modify/ create a new function for this task. the source code I want ...
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100 views

secp256k1 lib compiling issue “invalid use of incomplete type secp256k1_context”

I make a small test code (test.cpp), try to show the problem I meet: to compile use g++ -o test test.cpp -lsecp256k1 #include <stdio.h> #include "secp256k1.h" static ...
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133 views

secp256k1 recovery id and how does the code work

Here I have some questions regarding the recovery id (recid) defined in secp256k1 implementation. I had found few posts about how the recid is defined and what does it mean, also the source code (...
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46 views

Public key Exceeding Mod P? A Clarification Request On The Discrete Logarithm Problem

I tried to observe / implement the discrete logarithm problem but I noticed something about it; but before I get into it let me give some clarification which is open to correction. a = b^x mod P ...
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How to calculate the new sequence number N for the new final field Fp curve?

Are there simplified algorithms or online services or Python scripts where can calculate a new ordinal N for a new finite field Fp in an elliptic curve? y^2 = x^3 + 7 I know that SageMath exists and ...
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4 ERRORS GENERATED WHILE INSTALLING BITCOIND

I need your help plz. I have been struggling for weeks to make bitcoind work in my mac terminal. I installed all required programs and dependencies: xcode, bitcoin core, openssl, homebrew, and cloned ...
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122 views

Using secp256k1 in personal project

I am trying to use secp256k1 for a toy project that I am working on for learning purposes. I am using Ubuntu 20.04 and I can clone and compile the library just fine. I have tried to include it in a ...
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Linking libsecp256k1 as shared library to Bitcoin Core

I'm not sure if this question is better suited in the context of Autotools, but since it's about Bitcoin Core, I'll try to ask it here. I am trying to Compile/Link libsecp256k1 as a shared library ...
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How to change the field of the elliptic curve to the new value N while keeping the default Secp256k1 parameters?

I want to change the margin of the elliptic curve to the new N value, while doing so I want to keep the parameters Standard G-point Generator Secp256k1 that is, I want to replace: N = ...
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149 views

What are the co-ordinates of generator G in his uncompressed form on secp256k1?

I was looking at BitcoinWiki and it says that G, in it's uncompressed form, has a value of: G = 04 79BE667E F9DCBBAC 55A06295 CE870B07 029BFCDB 2DCE28D9 59F2815B 16F81798 483ADA77 26A3C465 5DA4FBFC ...
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53 views

In compressed public keys, is the 2 or 3 the parity or the sign?

In different places I've read that the 2 or 3 is the sign or is the parity of the elided Y coordinate? Which of these is it, or are the sign and parity equivalent in some way?
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Is there a simpler form of BIP32-like key derivation?

I've read about BIP32 key derivation functions, and also: Any Elliptic Curve could work in the BIP32 scheme. The only property of a Curve that BIP32 relies on is that a * G + b *G = (a + b mod N) * G,...
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Why doesn't basepoint G of Secp256K1 seem to be on the Elliptic Curve?

From what I understood are these the coordinates of basepoint G of Secp256K1 on the Elliptic Curve, in hexadecimal and decimal format. Hexadecimal Gx = (79BE667E F9DCBBAC 55A06295 CE870B07 029BFCDB ...
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250 views

Openssl magic values? Secp256k1 and ECDSA similarities? What makes secp256k1 special?

Part 1: Running this command seems to be a reliable way to produce a pubkey from a valid private key that for Bitcoin. Is this a correct assumption? openssl ec -inform DER -text -noout -in <(cat &...
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63 views

Does secp256k1 library provide API for generating uncompressed key?

Hi I am right now want to do a make a small tool to generate some test vector for ecdsa. Openssl is quite good, for support secp256k1 bitcoin provides an excellent library. However, it looks what I ...
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300 views

produce a public key from private key with ecc, with clear description about k=k*g

According to this answer: https://bitcoin.stackexchange.com/a/63996/100526 When he wants to generate a public key from the private key, he has used K=k*G. but I can't understand it's result. If we ...
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132 views

Positive or negative private key of a bitcoin wallet?

Private key is a number. Is the question positive or negative? Is it possible to know a positive private key or negative if you only know the public key? For instance: Positive private key: 2 ...
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626 views

How to subtract two points on an elliptic curve?

Please tell me if there is a formula for A-B, (That is, subtraction of two points / minus). I know how two points are added, A + B this addition is described in detail (Please tell me how you can ...
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122 views

Is it possible to add two secp256k1 points to get a “shared key”?

As I know from the Elliptic Curve Diffie Hellman (ECDH), you can create a "Shared Key": https://asecuritysite.com/encryption/ecdh2 This will look like this: dA × dB × G = Shared Key QB = dB × G QA ...
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297 views

Problem to link to libsecp256k1 on ARM architecture

Trying to compile with g++ -o addr 69_addr2.cpp $(pkg-config --cflags --libs libbitcoin) is getting me this error: /usr/bin/ld: /home/pi/libbitcoininstall/lib/libsecp256k1.a(libsecp256k1_la-secp256k1....
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128 views

Why not every [x,y] coordinate on the Secp256k1 curve corresponds to a valid uncompressed publicKey?

First, some background. 1. There are some coordinates x,y satisfying y^2(mod p)=x^3+7(mod p) on the Secp256k1 curve that do not correspond to a valid Bitcoin uncompressed publicKey of the form 04[x,...
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598 views

Is there a Python or SageMath implementation for solving the ECDL problem for small secret multiplier?

I am looking for a Python script or SageMath code implementation for testing the Baby Step - Giant Stepand Pollard Rhoalgorithms on the secp256k1 curve. I have read that these algorithms are well ...
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149 views

secp256k1.publicKeyCreate generating symbollic key

Following is my code: const bip39 = require("bip39"); var HDKey = require('hdkey'); var bip32 = require("bip32"); var bitcoin = require('bitcore-lib'); var EthereumBip44 = require('...
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301 views

What is the context in libsecp256k1?

I am experimenting with making a wallet for educational purposes, and would like to use libsecp256k1 directly. Aside from creating a context, and using it in calls, all I have perhaps learned so far ...
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415 views

Question about Python library coincurve/libsecp256k

I am a noob with cryptography, just trying to learn using python and the library Coincurve ( https://github.com/ofek/coincurve ) which is a mature Python binding for libsecp256k1. The following code ...
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674 views

Bitcoin scripts that force disclosure of the private key

Context: I am creating an example code that would demonstrate an atomic swap between Elements and Bitcoin, with the aim that the swap transactions cannot be trivially linked, as it would be with ...
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93 views

Private key generation doubt

I read that the private key pk has to be any number between 1 and n, where n is almost 10^77. Since pk' s function is practically to be used as a scalar for multiplying the generator point G, why does ...
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What is the reasoning behind the choice of 2^256-2^32-977 for the prime on the secp256k1 curve?

In Bitcoin's elliptic curve (secp256k1), the prime p = 2^256 - 2^32 - 2^9 -2^8 - 2^7 - 2^6 - 2^4 - 1 the generator point Gx = 0x79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798 ...
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177 views

Can a Bitcoin (secp256k1) key be converted to a Ed25519 (Tor v3) key?

If I have secp256k1 keypair that is widely known, like a Bitcoin address, can I convert that into a Ed25519 key pair such that someone could access a .onion address in a deterministic way?
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147 views

Generator Point G multiple

if in a curve y2 mod p = x3+ 7 mod p ( ecdsa-secp256k1) p=115792089237316195423570985008687907853269984665640564039457584007908834671663 G=...
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473 views

tiny-secp256k1 and ECDSA signing determinism

I noticed in bitcoin when using the tiny-secp256k1 library to sign the signature for a signature hash of an input, the signature is always the same. However in other ECDSA secp256k1 libraries (im ...
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991 views

How public key is calculated from a base58 encoded private key?

I followed this post and created a private key for bitcoin wallet. The post says after finding the random 256 bit(32 bytes) integer the version number should be prepended and the checksum should be ...
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354 views

Is there a list of coins that are bip-32 compatible?

BIP 32 allows me to derive keys based off a root key pair, and all these keys will be on the secp256k1 curve. That means I'll be able to use BIP 32 for other coins that are also based on your curve. ...
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211 views

Problematic Digital Signature with SECP256K1

I am trying to test out TestNet3 and I have a keypair generated using Java crypto library. The private key is 23F847360E1EB348A212F443C633058080A8EB9F05AD132F8B82D51FE672EADD and the public key is ...
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1k views

SECP256K1 Minimum Value for Private Key

I've been looking into Elliptic Curve Cryptography, in particular the SECP256K1 spec which is used in Bitcoin and Ethereum. So I understand that the Generator point G is fixed based on the spec and ...
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BIP32 recommends a 256 bit seed. Why do most Bitcoin wallets only use a 128 bit seed?

According to BIP32's "Master key generation" section, "256 bits is advised". See https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#Master_key_generation Why did BIP32 consider 256 bits ...
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1answer
3k views

How can a deterministic wallet have one private key but multiple public keys

If we take for example bread wallet. There is one mnemonic to remember, which means one private key? But when you use the app, your public address constantly changes. So more than one public key? ...
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434 views

Private key exported from Electrum, unable to recreate Address with Python

I have created a new Electrum wallet, and here is an address: 1JkZLnmFfpVFLT2ZMtKzc6BuXMdmY41EHA By right-clicking on it, I choose "Private key" which gives: ...
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1k views

How were the secp256k1 base point coordinates decided?

79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798,483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 seems very random to me. I see how this point is on the curve, but how ...
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517 views

C secp256k1: What do prefixes 0x06 and 0x07 in an uncompressed public key signify?

In the eckey_impl.h header file, the implementation of secp256k1_eckey_pubkey_parse checks if the first byte of a 65-byte public key is 0x04, 0x06 or 0x07. Where can I find documentation regarding the ...
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1k views

Why was the Schnorr code removed from Bitcoin Core?

I was looking for the Schnorr implementation in Bitcoin Core and was surprised to see that it was removed on Nov 2016 (commit e06e878fd7dcc99825025fa99aedb86bc7d5c29f). Why was the source code ...
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1answer
635 views

Is there a point on the secp256k1 curve for any given X coordinate?

There function in libsecp256k1 that allows you to directly set the field element to 32 bytes of your choice. Does secp256k1 always return a valid group element for any 32 byte value? ...
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2k views

Is the following a valid bitcoin private key? - FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE

In secp256k1 (Bitcoin's elliptic curve) it is defined that valid private keys may range from 1 to FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE BAAEDCE6 AF48A03B BFD25E8C D0364141 - 1. (https://crypto....
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C secp256k1: creating bindings in another language with FFI

I am attempting to create bindings from the C library libsecp256k1 into Scheme (the guile implementation) but I am guessing my question applies to other target languages. Say I want to export the ...
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85 views

C secp256k1: What is the purpose of the idiom '(void)data;'?

The following code is contained in the file secp256k1.c: static void default_illegal_callback_fn( const char* str, void* data) { (void)data; fprintf(stderr, "[libsecp256k1] illegal ...
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111 views

C secp256k1 : Segmentation Fault when passing NULL context to secp256k1_ecdsa_verify

Passing a NULL context to secp256k1_ecdsa_verify results in a segmentation fault (see attached code). I have the feeling this behavior is unintended as the secp256k1 library appears to be systematic ...