ASP.NET Core - Encrypt And Decrypt Public Key And Private Key

Introduction

In this article, we will learn how to encrypt and decrypt using a public key and a private key using ASP.NET Core.

Now we will start.

Step 1

First, we need to download the OpenSSL. To download it, go to the below URL.

https://slproweb.com/products/Win32OpenSSL.html

Download and install this .exe

Note, when you install, you have to change the path and install the C Drive (remove \Program Files in the path)

The current path is C:\OpenSSL-Win64

Step 2

Now generate a public key and a private key using the command prompt.

CMD Run As Administotor,

Command : cd/

Command : set OPENSSL_CONF=C:\OpenSSL-Win64\bin\openssl.cfg

Command : OpenSSL-Win64\bin\openssl.exe version

Command - OpenSSL-Win64\bin\openssl.exe req -x509 -nodes -days 3650 -newkey rsa:1024 -keyout privatekey.pem -out mycert.pem

In the output, you just hit the enter again and again when the next command is not shown.

Command : OpenSSL-Win64\bin\openssl.exe rsa -in privatekey.pem -pubout -out publickey.pem

Command - OpenSSL-Win64\bin\openssl.exe pkcs12 -export -out mycertprivatekey.pfx -in mycert.pem -inkey privatekey.pem -name "my certificate"

In this command, it asks to enter the password. You just enter the password and again need to enter the same password.

All the commands are done, now go to your C Drive and in C Drive you are shown 4 Files

In these files, mycert.pem file is the Public Key.

And mycertprivatekey is Private Key.

Now your ASP.NET project.

Just copy these two files and paste them to the wwwroot folder.

Now start with the code.

Goes to controller:

For encryption:

For decryption:

public static string DecryptUsingCertificate(string data) {
try {
byte[] byteData = Convert.FromBase64String(data);
string path = Path.Combine(_hostEnvironment.WebRootPath, "mycertprivatekey.pfx");
var Password = "123"; //Note This Password is That Password That We Have Put On Generate Keys
var collection = new X509Certificate2Collection();
collection.Import(System.IO.File.ReadAllBytes(path), Password, X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet);
X509Certificate2 certificate = new X509Certificate2();
certificate = collection[0];
foreach(var cert in collection) {
if (cert.FriendlyName.Contains("my certificate")) {
certificate = cert;
}
}
if (certificate.HasPrivateKey) {
RSA csp = (RSA) certificate.PrivateKey;
var privateKey = certificate.PrivateKey as RSACryptoServiceProvider;
var keys = Encoding.UTF8.GetString(csp.Decrypt(byteData, RSAEncryptionPadding.OaepSHA1));
return keys;
}
} catch (Exception ex) {}
return null;
}

Now we have just used this method:

In this article, we learned about Encryption And Decryption with the help of public and private keys using ASP.NET Core.

This article gives you a basic understanding of how we can generate a Public and Private Key with the help of Open SSL.

5 Comments

Join the conversation! Your thoughts help the community grow.

Abdalla Hassan4y ago
Excellent and thorough article, if you may pleased to do the same using ECDSA key with SHA256 and also explaining how to import the private key from a pem file to certificate using dotnet 4.7.. Thanks
Ramakrishna M4y ago
Can you explain the same to with a file.... say .pdf
Sílvio Bernardo5y ago
Awesome! Thanks!
Hamid Khan5y ago
Keep posting......................
Hamid Khan5y ago
Very good start......................