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c#bouncycastleputty

How to load PuTTYgen keys in Bouncy castle

I'm playing around with encrypting. I have got stucked on loading the keys with BouncyCastle. The keys have been generated by PuTTYgen (SSH-2 RSA 4096 bit). Is there maybe some other way to load it?

PuTTY-User-Key-File-2: ssh-rsa
Encryption: aes256-cbc
Comment: rsa-key-20160508
Public-Lines: 12

I get:

An unhandled exception of type 'System.IO.IOException' occurred in BouncyCastle.Crypto.dll
Additional information: unexpected end-of-contents marker*"

const string pubkey = @"AAAAB3NzaC1yc2EAAAABJQAAAgEAlX+AsmDF7FoR7D2jWYJTKLD6ZH6FAY9v2vPa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";

const string prikey = @"...";

var publickey = Convert.FromBase64String(pubkey);
//var privatekey = Convert.FromBase64String(prikey);

Org.BouncyCastle.Crypto.AsymmetricKeyParameter publicAsymmetricKey = Org.BouncyCastle.Security.PublicKeyFactory.CreateKey(publickey);
//Org.BouncyCastle.Crypto.AsymmetricKeyParameter privateAsymmetricKey = Org.BouncyCastle.Security.PrivateKeyFactory.CreateKey(privatekey);

ADDED: I generated a new key with "ssh-keygen -t rsa -b 4096" and tryed to load it with pemreader:

   const string pubkey = @"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";
    
   var pemReader = new Org.BouncyCastle.OpenSsl.PemReader(new StringReader(pubkey));
   // KeyParameter is still null
   var KeyParameter = (Org.BouncyCastle.Crypto.AsymmetricKeyParameter)pemReader.ReadObject();

ADDED:

I was able to generate a public key and also load a unencrypted private key (https://rietta.com/blog/2012/01/27/openssl-generating-rsa-key-from-command/)

openssl genrsa -des3 -out private.pem 4096

openssl rsa -in private.pem -outform PEM -pubout -out public.pem

openssl rsa -in private.pem -out private_unencrypted.pem -outform PEM

var publickey = Convert.FromBase64String(pubkey);
var privatekey = Convert.FromBase64String(prikey);

var asnprivate = Org.BouncyCastle.Asn1.Asn1Object.FromStream(new MemoryStream(privatekey));
var privStruct = new Org.BouncyCastle.Asn1.Pkcs.RsaPrivateKeyStructure((Org.BouncyCastle.Asn1.Asn1Sequence)asnprivate);
   
AsymmetricKeyParameter publicAsymmetricKey = PublicKeyFactory.CreateKey(publickey);

But I was not able to load the encrypted private key...

Solution

  • With the openssl PEM I was able to make it to work. I continue to find out how to load load the protected private key.

    Thanks for all the input.

    using System;
using System.IO;
using System.Text;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1;

namespace EncryptTest1
{
    class Program
    {
        static void Main(string[] args)
        {
            const string pubkey = @"MIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAuQhcZKNnIC2bvJhI5Yzq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";
            const string prikey = @"MIIJKQIBAAKCAgEAuQhcZKNnIC2bvJhI5YzqoH9uGAHuiAt9bOXdIrsaeEwsIUMu
yNfXkLozwlcJb0YLgqhpP3gNLb58WCb1AvkVZHgzLQbay93HwmBiEPW6LZIKGsHw
h1awBmJpeWhU8h3oNP+KpNq44H+jAeM9G9EnW0y7+AUbe3pnisOWVZHmM72A2mLq
1piCOjmvjegzgB8/rU7ZkRrNadeFO7DBP0Ew6eElS3iXfFHJmbK+L5lL0pFxvUMR
fGVC33NQkuSoWiQJZsYyUgIk6WSOQm3t5fw6VESMTfd1xKlaBGp7IrWksthEF+XA
u5ziAcSdjBwJLEFzJ2830cQ4GhFS3JtU/Iao6MbJkUuaHoI3Xx9C7d6RiKbK1uZr
OHjyVsUhqpYwyAUdrViraj0pybxbE2GwbRC4/NyHuPKG3gBULiGYbl8wwlhl71nR
VdkPQtGw36kmGWHRk3ERM6JgLWsDZjED4ak2Na6VzIvnqVs0HROl/4Rd4rHZvl9t
39tfVBtofEkD4C0B5BdgW/B2XQM7Fd4celn3q/+FKmvaVydoFGG0s4YZL6hsqOIS
fhdT10jGrwNKe+zupnrXZO66mtX8rvPtY4x2WXcHrbp1cgSr+2r8Mteh8Eff+6rq
ArU1i1ezDm3SrKs1WMFKu1hRKDYudfOaB/L7gvEvD+lUE9qnjlYUBGSXKMUCAwEA
AQKCAgBdi6GSa54egZBjx6XLD/Qq0mHpl0ht1UlC/e9PuMJIIVKKOnnzplPgYpL6
ZKBrdkEpfFVBdkNLZitdMczbBOzQz4gn8ng5a1WrqqjJpEHM+jFLl9MvyR7TC3wB
mkKf6YjVCoCgmcewEDdsI+NoJdS87s11NbfQNHEWkY12k32LmPoE7s+FULM+Fp3v
o34t/x5lUyDhoGhLY1+Dbvg0L5Q4GdCOGFiVzI+cueY3EExqF4gmRDsZ5ePqLlWE
/j8y21c5c2hLV7Qrnt/hK8yDYoJmygUZAcuzcl8FLoQ0ZxruJDJA1rIa59THSgzQ
offtPOWoAS16SraGT03SJGHSDY5kzCZkEx7MJv8dn5hydLzJ5bzbiJ1rheNdZNzp
yjT/X61jtjQnX2gmev/bN4Q54qqc2YbVfh7BwvyBAL2c7oHxFP3xmJgCZt6OS6S1
HUR8/QDrcLJVwNNsTL7uvToSiRBrTWjFUuc0k6m2h8takD9sONHH7+hZu9TEL2a9
/bjowuPIrmrrYbgYN9DospmJZrDfEby79+t8aDsycAzK3uHIn1GfdhDVNFayJjPR
VP593GRhY/B6CwM7lCFxzTqOU4e9ITLpkLV//CpK77g9xGVUGQk1X0NieBbzUtHY
DzSnsC2k9dOwootlrMvJYTUv3+BdzG3jEleCP6qoYxd43iKtAQKCAQEA61HUaI9v
dlxIK/oG5RWYSFZHCc0oOeTMw1MJ+rOQ5c3RUbIrn/fj+i2zGknt5b+5LH6i5jXw
YEY4o1bJJCjT51AhdV6HxlljAfUeX98T2uaVVZxQJio/uqJg9N63s9bIhdq94NJg
MWIRKsip76gV76qXhFRyRXfEjQvy9PZHC/A2Qs+azrcD97jnzf/XzOpnot+W8Ul1
b2fOHk0RqdQs2ZJ/ajZrVnK40WX3AZlSVYZuwPKaW90BtifxjZUESGAIsAzh7Eve
tX3lgpsDP7JaBZZYdP6AzDEkjPKDFH4P/KmEHl9eWHfcuVu+T+Er3xFe94PUbW9P
f52XbXox4OrYQQKCAQEAyUsvez7ri7/bXcUcrfjHHQuSs5Mw+R0yyg77yT8o6nkB
6cDWT4BmIc/+IoTIAXySOczftVxjL1bXrsYQSYLkoTKOuYAQRi0zN3/alTFW2A3P
7ec8hANTuxAXCwuNd1jjEtVaOEuNdVYg4gsEmHEvejJsBIDJkT/VzbYJVB+Y1k3J
Sd0R6h0KAROsJ4lefK9kh7MzN8B/SUDeuiaPkxBzrMzGFeDifieWiyxWTqoGPHUV
eO5NfJSYHfn7VmEvB3cNmqcc56i9Thie6a0iDUbKmkwPfDmEABu3ex9HctpnYOCk
gzR/huwPiWP1IGYznilwIOvt/mdyiAPmGQn6xakPhQKCAQEAlDfLgTxvKW8Aqmpm
c16Bt3ZYckz9fFGnw5OHIph9uLFFmZ6OqciamNa2C+Xq6R40hVkSQ8xPpmQ0gnVE
ZfktV3H6URIElSNyICaDRkGdIPDBuNWnChLsZyKlzTaHIMg1L1JS7Mu1eQVa6MbR
erk1b+rUWq5R931zmJ+hHTgOEe/wTW60BGX0ItEdeHwgMdqnAkiwqzPouw34Hs/O
Q1j4EuaaSI0UWLQTwxjlVuV6nZH6Kp/kJ95xmIlaNSJaOzf54OGMX6h+E3TD3drD
VhiBaSmEd9RhzbtaWUja1Up9yVgAdpz9MN32ce3eVjPuzScE2QP5BiDpQulBGtyv
lAp3wQKCAQAyf2sc9w7uUyY8Iuvr9QI2liWqaR2bESkhqZqexPqFv++r7ZWWAjcc
+mndzQPD47VnTK8+dzvmr1mSXdvOJUkn62AEx0zN3h8AKFH0pZkMwIJOQ3laAN+r
iQDO44oMy77DhcSJZOLK8d1z96GigJqRhD627nwitSn03lr+wKJ9+KurnQsWeUx+
Mqo4jOyoSPPmWx1ZOjB0dxKpDm1sTm9GhWSYLn+DeHj61xebymmgFxtY6CeGPlzf
AEx+QgkjTUmbZ5sHvrwm8GRFaQqm3ACNrtEfr+oegNWJzLIG7SWMFy8OP0hS17ua
Evp2s0z1u52GlMlyzg7ccmXyGB/SIHRlAoIBAQCqF/P8D+T8uEiiQron39NAGgSM
FFyi1uj3IeDrDPgdsLT5TtpFOnHpUMjhxVEhdIQm2K4MH44/aBW40CgS+OGHclay
SzwdtfHyPuK1H8TwaJqgA5NYu/xTyiR8QqRE+qwwh5wMH4f4ErhKglnQJVNxHeo7
ZlRul6vFgS3uaaEyaPXrG5pFRPeLlqllJxQ5Z1mQtqaK9U0dSCykxW6zaz3d8YXE
BIe/0Vc1/0d80lkJk/3SnLGIAiC2C9dpmA6RmgkGa0cyD5QPmXmYXHFT+tA7S/lV
W+5C6ZO0aaOmO+F+W82ZJ92FRd8CITasoPO9zxalJBEGD/s5ehnRhhizLqjY";

            var publickey = Convert.FromBase64String(pubkey);
            var privatekey = Convert.FromBase64String(prikey);

            var asnprivate = Asn1Object.FromStream(new MemoryStream(privatekey));
            var privStruct = new RsaPrivateKeyStructure((Asn1Sequence)asnprivate);

            RsaKeyParameters privateAsymmetricKey = new RsaKeyParameters(true, privStruct.Modulus, privStruct.PrivateExponent);
            RsaKeyParameters publicAsymmetricKey = (RsaKeyParameters)PublicKeyFactory.CreateKey(publickey);

            var inputBytes = Encoding.UTF8.GetBytes("the message");

            Console.WriteLine("--- Message: ----");
            Console.WriteLine(Encoding.UTF8.GetString(inputBytes));

            IAsymmetricBlockCipher cipher = new RsaEngine();
            cipher.Init(true, publicAsymmetricKey);
            var cipheredBytes = cipher.ProcessBlock(inputBytes, 0, inputBytes.Length);

            Console.WriteLine("--- Enc utf8: ----");
            Console.WriteLine(Encoding.UTF8.GetString(cipheredBytes));

            Console.WriteLine("--- Enc Base64: ----");
            Console.WriteLine(Convert.ToBase64String(cipheredBytes));

            cipher.Init(false, privateAsymmetricKey);
            var deciphered = cipher.ProcessBlock(cipheredBytes, 0, cipheredBytes.Length);

            Console.WriteLine("--- Dec: ----");
            Console.WriteLine(Encoding.UTF8.GetString(deciphered));
            Console.ReadLine();
        }
    }
}