cscの作法 その212

概要

cscの作法、調べてみた。
BouncyCastle.Crypto.dll使ってみた。
練習問題やってみた。

練習問題

暗号を復号せよ。

方針

平文は、「hogehoge2」。
rsaで作る。
秘密鍵、公開鍵の両方で、やる。

サンプルコード

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Operators;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Prng;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.OpenSsl;
using Org.BouncyCastle.Pkcs;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.X509;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Crypto.Encodings;

namespace ConsoleExample
{
	class Program {
		static void Main(string[] args) {
			var myenc = File.ReadAllText("myenc.txt");
			var encrypted = Convert.FromBase64String(myenc);
			var privateKeyPem = new StreamReader(@"myprivatekey.pem", Encoding.ASCII);
			var privateKeyReader = new PemReader(privateKeyPem);
			var keyPair = (AsymmetricCipherKeyPair) privateKeyReader.ReadObject();
			var rsa = new Pkcs1Encoding(new RsaEngine());
			rsa.Init(false, keyPair.Private);
			byte[] decrypted = rsa.ProcessBlock(encrypted, 0, encrypted.Length);
			Console.WriteLine("decrypted: " + Encoding.UTF8.GetString(decrypted));

			var myenc2 = File.ReadAllText("myenc2.txt");
			var encrypted2 = Convert.FromBase64String(myenc2);
			var publicKeyPem = new StreamReader(@"mypublickey.pem", Encoding.ASCII);
			var publicKeyReader = new PemReader(publicKeyPem);
			var publicKeyParam = (AsymmetricKeyParameter) publicKeyReader.ReadObject();
			var rsa2 = new Pkcs1Encoding(new RsaEngine());
			rsa2.Init(false, publicKeyParam);
			byte[] decrypted2 = rsa2.ProcessBlock(encrypted2, 0, encrypted.Length);
			Console.WriteLine("decrypted: " + Encoding.UTF8.GetString(decrypted2));

		}
	}
}

実行結果

>bc11
decrypted: hogehoge2
decrypted: hogehoge2

以上。