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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4
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1answer
118 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 ...
0
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1answer
23 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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0answers
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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,...
7
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1answer
446 views

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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2answers
96 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 &...
0
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1answer
43 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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0answers
77 views

How do I Enable ECDH in secp256k1-py?

I removed the libsecp256k1 that was previously installed to my system. I cloned repo https://github.com/bitcoin-core/secp256k1.git. I configured it with: $ ./configure --enable-experimental --...
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2answers
106 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 ...
2
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1answer
73 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 ...
2
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3answers
269 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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1answer
93 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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2answers
183 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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1answer
85 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,...
0
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1answer
314 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 ...
0
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0answers
111 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('...
0
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1answer
214 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 ...
0
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1answer
293 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 ...
3
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1answer
460 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 ...
0
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1answer
84 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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3answers
1k views

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 ...
3
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2answers
153 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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1answer
129 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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1answer
402 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 ...
0
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1answer
694 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 ...
2
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1answer
310 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. ...
0
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1answer
203 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 ...
2
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1answer
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 ...
6
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2answers
1k views

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 ...
5
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1answer
2k 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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2answers
356 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: ...
5
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1answer
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 ...
5
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1answer
458 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 ...
8
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1answer
949 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 ...
6
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1answer
560 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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1answer
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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0answers
48 views

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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2answers
76 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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0answers
103 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 ...
3
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1answer
341 views

C secp256k1 : what is the purpose of secp256k1_context_randomize?

In the course of studying the secp256k1 library API, I came acrosssecp256k1_context_randomize which seems similar to providing a seed to a pseudo-random generator. At the same time, the file secp256k1....
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1answer
151 views

C secp256k1 : ec_pubkey_parse successful on NULL context despite attribute

Looking at the main API file secp256k1.h of the C library, we have: SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_parse( const secp256k1_context* ctx, secp256k1_pubkey* ...
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0answers
978 views

Cannot build secp256k1 C library on Debian stretch

I was hoping that someone would be able to suggest something about this (the same process works perfectly fine on my Debian Jessy machine) $ uname -a Linux front 4.8.0-1-amd64 #1 SMP Debian 4.8.7-1 (...
4
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1answer
2k views

OpenSSL and Secp256k1 differing in implementation of ECDSA signatures?

OpenSSL (from ssl in Mac OS X Version 10.11.6) and Secp256k1 (from the bitcoin-core repository) seem to differ in their implementations of ECDSA. I'm having issues with these differences and want to ...
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0answers
459 views

Can I quickly check the cofactor of secp256k1 is 1

I was wondering if there was a quick way to check that the group underlying the elliptic curve secp256k1 was indeed cyclic with the usual point G a generator. I am given the prime number underlying ...
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2answers
2k views

C++ and secp256k1

I am working on a tiny C++ bitcoin application for a university project. I'm using Blockcypher API to create transactions, but I faced a problem with signing transaction's hash that returns one of the ...
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2answers
714 views

How do I add two secp256k1 keys together?

I have two public/private keypairs, A and B. I want to add them together to get a new keypair AB. I'd also like to be able to add the public keys of A and B to get the public key of AB. How do I do ...
4
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1answer
727 views

How to determine if a public key point y is negative or positive, odd or even?

Take a bitcoin public key (x, y) and its additive inverse (x, -y). How do you identify which is the positive point and which is the negative point? Example Private key 1 -> (x, y) x = ...
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1answer
194 views

x , y coordination division

python code def inverse(x, p): return pow(x,p-2,p) p = 0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f #private key 2 -->(x , y) value xx = ...
4
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1answer
2k views

order of group of points of secp256k1

points on curve secp256k1 form a group E(Fp) over field Fp. p = 2^256 - 2^32 - 2^9 - 2^8 - 2^7 - 2^6 - 2^4 - 1 is prime. n is the order of group E, n=...
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3answers
2k views

How do you derive the lambda and beta values for endomorphism on the secp256k1 curve?

You can see a little background about this on this bitcointalk post by the late Hal Finney. Beta and lambda are the values on the secp256k1 curve where: λ^3 (mod N) = 1 β^3 (mod P) = 1 As seen ...
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2answers
226 views

What sort of tasks can an ASIC be developed to do?

I know requiring a lot of memory is one thing that makes an algorithm ASIC resist. Are there any others? Could an ASIC be developed to do Elliptic Curve Crypto? Like adding two points, or signing a ...