generating public key from private key on the command line

[cyberguy]

is there any command line utility that can be used to do the secp256k1 calculation on a given hexadecimal number (private key) and print the result (public key) to stdout in compressed and/or uncompressed form. can this be done using openssl ?

[1715396253]

1715396253

[1715396253]

1715396253

[piotr_n]

you can use gocoin for that - the lib or the wallet app

[cyberguy]

you can use gocoin for that - the lib or the wallet app

I need something that can run on a 32-bit machine with low memory requirements

[piotr_n]

you can use gocoin for that - the lib or the wallet app

I need something that can run on a 32-bit machine with low memory requirements

It does. You only need the wallet tool, which has tiny requirements. It even runs on Raspberry Pi.

[piotr_n]

Try this:

Code:

package main

import (
	"fmt"
	"encoding/hex"
	"github.com/piotrnar/gocoin/lib/btc"
)

const PRV_KEY_HEX = "AB9EA551E262A87A13BB90591BE7B545CDF3FD0E1234567890ABCDEF12345678"
const COMPRESSED = false

func main() {
	private_key, _ := hex.DecodeString(PRV_KEY_HEX)
	fmt.Println(hex.EncodeToString(btc.PublicFromPrivate(private_key, COMPRESSED)))
}

You will just need to fetch gocoin package first (having go and git installed):

Code:

go get -d github.com/piotrnar/gocoin

[cyberguy]

Try this:

Code:

package main

import (
	"fmt"
	"encoding/hex"
	"github.com/piotrnar/gocoin/lib/btc"
)

const PRV_KEY_HEX = "AB9EA551E262A87A13BB90591BE7B545CDF3FD0E1234567890ABCDEF12345678"
const COMPRESSED = false

func main() {
	private_key, _ := hex.DecodeString(PRV_KEY_HEX)
	fmt.Println(hex.EncodeToString(btc.PublicFromPrivate(private_key, COMPRESSED)))
}

You will just need to fetch gocoin package first (having go and git installed):

Code:

go get -d github.com/piotrnar/gocoin

thanks, will give it a try

[unknown9387]

First question, did the previous suggestion work.  2, if you don't mind telling us, would you be willing to explain what you're trying to do?  I have a simple python program that could easily be modded to just spit out public keys.  Though I don't think I have one that will allow you to input (on the command line, as opposed to actually putting it into the python program itself).  I also think the one(s) I have would require a decimal input.  Just asking.

[YarkoL]

Yes gocoin works just fine.

You can also do this very simply with
pybittools

https://github.com/vbuterin/pybitcointools

right at the start of the readme is an example.

[bit22gen]

is there any command line utility that can be used to do the secp256k1 calculation on a given hexadecimal number (private key) and print the result (public key) to stdout in compressed and/or uncompressed form. can this be done using openssl ?

bitgen can be used:
http://bitcoin-gen.org/

Currently it will require two commands to get the information, but modifying the source to give all information at once is trivial.
It can run on a 32-bit machine and has low memory requirements.

For example:
$ bitgen hex 12312381273918273128937128912c3b1293cb712938cb12983cb192cb1289b3 info

Would give:
Wif    : 5HxJGdttiqC6hd4wXyExr8Jmv6WugaCtZtteoT8MCj74fhanXrQ

Next:
$ bitgen info 5HxJGdttiqC6hd4wXyExr8Jmv6WugaCtZtteoT8MCj74fhanXrQ

Gives:
Public point  :(6B4D16EF98953A36752D7A2776B5989ED8700B8F80ECAA1818F15E3EF31D1532
              : E9B6F7C6BE1017AC8D0A733DD099CBBB3A0DAEC89514F50F57A4B0259ACC0F10)
Public key    : 046B4D16EF98953A36752D7A2776B5989ED8700B8F80ECAA1818F15E3EF31D1532E9B6F7C6BE101 7AC8D0A733DD099CBBB3A0DAEC89514F50F57A4B0259ACC0F10

[cyberguy]

is there any command line utility that can be used to do the secp256k1 calculation on a given hexadecimal number (private key) and print the result (public key) to stdout in compressed and/or uncompressed form. can this be done using openssl ?

bitgen can be used:
http://bitcoin-gen.org/

Currently it will require two commands to get the information, but modifying the source to give all information at once is trivial.
It can run on a 32-bit machine and has low memory requirements.

For example:
$ bitgen hex 12312381273918273128937128912c3b1293cb712938cb12983cb192cb1289b3 info

Would give:
Wif    : 5HxJGdttiqC6hd4wXyExr8Jmv6WugaCtZtteoT8MCj74fhanXrQ

Next:
$ bitgen info 5HxJGdttiqC6hd4wXyExr8Jmv6WugaCtZtteoT8MCj74fhanXrQ

Gives:
Public point  :(6B4D16EF98953A36752D7A2776B5989ED8700B8F80ECAA1818F15E3EF31D1532
              : E9B6F7C6BE1017AC8D0A733DD099CBBB3A0DAEC89514F50F57A4B0259ACC0F10)
Public key    : 046B4D16EF98953A36752D7A2776B5989ED8700B8F80ECAA1818F15E3EF31D1532E9B6F7C6BE101 7AC8D0A733DD099CBBB3A0DAEC89514F50F57A4B0259ACC0F10

THIS is exactly what I wanted. In fact it is more than what I wanted. Thanks a lot.

To all those who posted above. Thanks for your replies. But I will only be considering bitgen, since the features I need are present in it.