 using System;
using System.IO;
using System.Text;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.OpenSsl;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.X509;

namespace security_sandbox
{
    class Program
    {
        static void Main(string[] args)
        {

            var certificateString =  @"-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----";
            var pemreader = new PemReader(new StringReader(certificateString));
            var cert = (X509Certificate)pemreader.ReadObject();

            // Alternatively, load the public key directly
            var pubkeyString = 
@"-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE7f1xwQL5m/UcN4zL+zsly6V1g3/w
NcL5TdCfWt0XfnUfg0x+RsIf1uerBnhrmhH0cN9o0xfXg5B3hURFlXVuEQ==
-----END PUBLIC KEY-----";
            pemreader = new PemReader(new StringReader(pubkeyString));
            var pubkey = (AsymmetricKeyParameter)pemreader.ReadObject();

            var data = "Hello";
            var signature = Convert.FromBase64String("MEUCIQD5593C/NBhHA1DILT72gjhGj/lKjom9vYP+JbuypBrxQIgNAjYT1LihEpPbUhe1n9ccUHQvw676bGqOTEU/25qcRQ=");

            // Verify using the public key
            var signer = SignerUtilities.GetSigner("SHA-256withECDSA");
            signer.Init(false, pubkey);
            signer.BlockUpdate(Encoding.ASCII.GetBytes(data), 0, data.Length);
            var success = signer.VerifySignature(signature);

            if (success) {
                Console.WriteLine("Signature verified successfully using public key");
            } else {
                Console.WriteLine("Failed to verify signature using public key");
            }

            // Verify using the certificate - the certificate's public key is extracted using the GetPublicKey method.
            signer.Init(false, cert.GetPublicKey());
            signer.BlockUpdate(Encoding.ASCII.GetBytes(data), 0, data.Length);
            success = signer.VerifySignature(signature);

            if (success) {
                Console.WriteLine("Signature verified successfully using certificate");
            } else {
                Console.WriteLine("Failed to verify signature using certificate");
            }
        }
    }
}

created 4 years ago

C Sharp Online Compiler

Write, Run & Share C# code online using OneCompiler's C# online compiler for free. It's one of the robust, feature-rich online compilers for C# language, running on the latest version 8.0. Getting started with the OneCompiler's C# compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C# and start coding.

Read inputs from stdin

OneCompiler's C# online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

using System;
 
namespace Sample
{
  class Test
    {
      public static void Main(string[] args)
       {
         string name;
         name = Console.ReadLine();
         Console.WriteLine("Hello {0} ", name);
	}
     }
}

About C Sharp

C# is a general purpose object-oriented programming language by Microsoft. Though initially it was developed as part of .net but later it was approved by ECMA and ISO standards.

You can use C# to create variety of applications, like web, windows, mobile, console applications and much more using Visual studio.

Syntax help

Data types

Data Type	Description	Range	size
int	To store integers	-2,147,483,648 to 2,147,483,647	4 bytes
double	to store large floating point numbers with decimals	can store 15 decimal digits	8 bytes
float	to store floating point numbers with decimals	can store upto 7 decimal digits	4 bytes
char	to store single characters	-	2 bytes
string	to stores text	-	2 bytes per character
bool	to stores either true or false	-	1 bit

Variables

Syntax

datatype variable-name = value;

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition or set of few conditions IF-ELSE is used.

if(conditional-expression) {
   // code
} 
else {
   // code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement) {
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

data-type[] array-name;

Methods

Method is a set of statements which gets executed only when they are called. Call the method name in the main function to execute the method.

Syntax

static void method-name() 
{
  // code to be executed
}