go-ethereum | Go language implementation of the original/classic design | Blockchain library

I'm trying to attach to a go-ethereum node from a go script:

I am trying really hard to convert Ethereum private keys BIP44 in string format to a type that can (*ecdsa.PrivateKey) be used by rest of the code.

The following site is frequently referenced and, I assume, accurate:

https://gobittest.appspot.com/Address

I'm trying to repro these steps in Golang but failing at the first step :-(

Is someone able to provide me with a Golang snippet that, given a ECDSA private key, returns the public key? I think I may specifically mean the private key exponent and public key exponent per the above site's examples.

i.e. given e.g. a randomly-generated (hex-encoded) private key (exponent?) E83385AF76B2B1997326B567461FB73DD9C27EAB9E1E86D26779F4650C5F2B75 returns the public key 04369D83469A66920F31E4CF3BD92CB0BC20C6E88CE010DFA43E5F08BC49D11DA87970D4703B3ADBC9A140B4AD03A0797A6DE2D377C80C369FE76A0F45A7A39D3F

I've found many (relevant) results:

https://crypto.stackexchange.com/questions/5756/how-to-generate-a-public-key-from-a-private-ecdsa-key

But none that includes a definitive example.

Go's crypto/ecdsa module allows keys to generated and includes a Public function on the type but this returns the PublicKey property.

Alternative ways that start from a private key appear to require going through a PEM-encoded (including a DER-encoded ASN) form of the key which feels circuitous (and I would need to construct).

See the answers below: andrew-w-phillips@ and kelsnare@ provided the (same|correct) solution. Thanks to both of them!

For posterity, Bitcoin (and Ethereum) use an elliptic curve defined by secp256k1. The following code from andrew-w-phillips@ and kelsnare@ using Ethereum's implementation of this curve, works:

I'm trying to debug Go implementation of ethereum(link), because my core interest is in developing new consensus algorithm (i.e. modify the open source Go code from github).

However, I'm having problem with the location/path of the source code. When I put the folder(i.e. go-ethereum) outside of the $GOPATH and then try to compile&debug geth(go-ethereum/cmd/geth/main.go) it shows the following error: Use of internal package is not allowed.

From that error message, I figured out that the import github.com/ethereum/go-ethereum was not importing my source, and instead it was getting code from internet(like other libraries). Which of course is definitely what I shouldn't do when I'm trying to modify the github.com/ethereum/go-ethereum package code.

So, my workaround was to clone the source code into $GOPATH/src/github.com/ethereum/go-ethereum and followed this answer, and Goland IDE started compiling&debugging without error (wasn't able to go build ./cmd/geth/main.go though due to error undefined: configFileFlag...)

Thereby now I've got a working debugger that can debug with my source code modification, but this doesn't look like ideal source code structure.

The question is:

Is putting source code inside $GOPATH(because of internals) a proper approach? If so, what if I was using go-ethereum package from another project?(Fortunately I'm not, but I'm curious) Do I have to stash&revert changes I made to the code?

I'm getting used to Go, and trying to understand how it works.

So I'm trying to run the test code from my repository zoonoo/go-ethereum, forked from the original repository ethereum/go-ethereum.

When I run go test . under the eth directory, I get the following error :

It's easy to use web3js to call functions that don't require signing (e.g. functions that do not update the state of a contract). However, it's not clear how to call functions that require signing, other than manually unlocking my MetaMask wallet and calling functions inside Remix environment.

After deploying my dapp for the first time to Ropsten, I need to call createItem(string name, uint price) 100 times to populate the items array initially. Since I don't want to do it manually in Remix, I want to write a script that does it automatically.

It looks like I need to have ethereumjs-tx in addition to web3js to sign transactions programatically without having MetaMask. I also need to have my account and privateKey. With all this information and the official web3js doc, I come up with the following:

Newbie. There is a go-ethereum method:

eth.estimateGas({from:'firstAccount', to:'secondAccount'})

that works well, but same method with contract address like:

eth.estimateGas({from:'firstAccount', to:'contractAddr'})

fails with error

gas required exceeds allowance or always failing transaction

I have looked into go-ethereum source code and it has the line, that contains proposal to use contract address as second parameter: https://github.com/ethereum/go-ethereum/blob/master/accounts/abi/bind/base.go#L221

The question is: is there any possibily to use eth.estimateGas with contract address as second parameter and how to avoid above error? Thank you.

I'am writting a script to interrract with a smart contract:

I've written a small go program to be run on a MIPS 32-bit router. I'm able to get a basic hello world program running on the router using the go build toolchain.