Monday, August 10, 2020

Create a JWT singed with RSA private key in .net core

The following example is a snippet of a C# code that generates an RSA private key out of a .pem file and uses it to sign a JWT. The privateKey variable, stores the contents of the .pem file minus the "-----BEGIN RSA PRIVATE KEY----" and "-----END RSA PRIVATE KEY-----" lines.

string privateKey = @"
byte[] RSAprivateKey = Convert.FromBase64String(privateKey);
RSA rsa = RSA.Create();
rsa.ImportRSAPrivateKey(RSAprivateKey, out _);
var jwt = tokenHandler.CreateEncodedJwt(
   issuer: "...",
   audience: ...,
   signingCredentials: new SigningCredentials(
     key: new RsaSecurityKey(rsa),
     algorithm: SecurityAlgorithms.RsaSha256)

Thursday, April 9, 2020

Deploying smart contracts to ganache using python and web3

Ganache is a useful tool that emulates Ethereum blockchain in your local machine and it is very practical for testing smart contracts. Most tutorials explain how to deploy a smart contract in ganache using truffle, which is a development framework by the same company. But this is not necessary. Here, I explain how to write and compile a contract using Remix, and deploy it using python and

Write your smart contract in remix and compile it. Then press the "ABI" button on the bottom left (see picture) and paste the output in a file. This will be our ABI_file. Do the same with the "Bytecode" bottom. This will be the bin_file. Then you can use the python script from this github repository. Make sure you have installed the dependencies and that you have modified the ABI_file and bin_file variables of the script accordingly.