Using Python: create a private key of my choosing, then generate public key and address

Question

I'm looking for a simple, easy to use Bitcoin library for Python.

What I want to do is verify I can enter a hex private key that I want, and get the expected pubkey in compressed format, and the 1Btc... address.

I've looked at cryptotools on github which looked promising, and easy to use, but it would not accept a hex value that wasn't a multiple of 2. I know that sounds odd, but I want to be able to enter a hex value like c12 and have it work as expected (unless I have to enter 0c12 and that will work, with the leading zero discarded). I expect than when I enter 0cfa721d that this will be interpreted as big endian.

bitcoinlib looks promising, but I find it confusing and I've tried for a couple of hours but unsure of how to get what I want.

1. Input private key in hex
2. Get back pub key in hash160 format, compressed
3. Get the 1Btc... address as well.

I wonder if this is a strict mathematical relationship. For instance could there be an arbitrary or infinite number of pub keys from the private key? Is there a way to ensure I get the pubkey I want from the private key? I want to test known private keys with the pubkey and BTC address generated that corresponds to known private keys and addresses, so I can try and figure out how whoever generated these addresses from choices of private keys I can try to replicate and do the same thing myself.

Thank you for any help or suggestions.

Answer 1

For this very reduced case, you can take a look at https://github.com/circulosmeos/bitcoin-in-tiny-pieces

It has each operation coded for ease of understanding, isolated in a different file, but they're easy to join or to use directly from command line: for example:

$ echo 0x01 | ./bitcoin-public-from-private.py | ./bitcoin-address-from-public-key.py

And for the question:

For instance could there be an arbitrary or infinite number of pub keys from the private key?

In principle, from a private key only one public key is derived: but this can be coded in three different Bitcoin addresses. Normally only one or two of these formats are used.

This is in the most simple case, not considering more complex cases introduced later in Bitcoin (like HD keys, etc)...

Answer 2

I find the Bit module the easiest and most straight forward, albeit a tad, limited but with bit you can simply:

from bit import Key

# To generate private key
privKey= Key()

# Create Ripemd-160 Hash (address)
privKey.address

# or 

myAddress = privKey.address

# Segwit

MySegwitAddress = privKey.segwit_address

You can also import your own existing private keys like so:

# For wif format:
privKey = Key.('L1VotKmtZRLZSnSPhLhQxfts2aqBMru2APTs4Yuc8TYJ4jNhQoGB')

# For hex format:

privKey = Key.from_hex('ccb8c423403f4d5b6cde505d2a8f39d1d9399f6e06853339f5b11593cc502dc9')

# For int format:

privKey = Key.from_int('92598274663553697917256765988661195316245391320286084491562671024534692310473')

privKey = Key.from_byte('b'\xcc\xb8\xc4#@?M[l\xdeP]*\x8f9\xd1\xd99\x9fn\x06\x8539\xf5\xb1\x15\x93\xccP-\xc9')

Exporting works pretty much the same way as importing except you replace from.[format here] with to.[format here], you can even import or export a PEM file of your private key.

The documentation is enough for the library to give you the core functions, but is also somewhat lacking, for example you can't create compressed bitcoin addresses. But otherwise you can sign, send transactions, even select exactly which outputs you want to use .etc