Bouncy Castle, RSA: transforming keys into a String format_问答_开发者

I'm using RSA (Bouncy Castle API) in my C# project. I generated the keypair with this method:

RsaKeyPairGenerator r = new RsaKeyPairGenerator();
r.Init(new KeyGenerationParameters(new SecureRand开发者_如何学Goom(), 1024));
AsymmetricCipherKeyPair keys = r.GenerateKeyPair();

AsymmetricKeyParameter private_key = keys.Private;
AsymmetricKeyParameter public_key = keys.Public;

Now I want to save them in a txt file but the problem is that I can't convert them to a string format. I read in another post that keys must be serialized using:

PrivateKeyInfo k = PrivateKeyInfoFactory.CreatePrivateKeyInfo(private_key);
byte[] serializedKey = k.ToAsn1Object().GetDerEncoded();

Is it the right way? If yes, what should I do after this? Just convert them from byte[] to String?

You could also use PemWriter to store them in PEM format:

TextWriter textWriter = new StringWriter();
PemWriter pemWriter = new PemWriter(textWriter);
pemWriter.WriteObject(keys.Private);
pemWriter.Writer.Flush();

string privateKey = textWriter.ToString();

Now privateKey contain something like this:

Well, I don't know about the RSA-specific side, but once you've got an opaque binary string (i.e. it could contain any arbitrary data) the best bet for text conversion is Convert.ToBase64String(byte[]) which you can reverse with Convert.FromBase64String(string).

Do not use Encoding.GetString(byte[]) and Encoding.GetBytes(string) for this - the binary data isn't text in a particular encoding, and shouldn't be treated as such. You're almost bound to lose data if you try this.

This might be what you are looking out for: http://www.rahulsingla.com/blog/2011/04/serializing-deserializing-rsa-public-private-keys-generated-using-bounty-castle-library

Try the following

        RsaKeyPairGenerator rsaKeyPairGenerator = new RsaKeyPairGenerator();
        rsaKeyPairGenerator.Init(new KeyGenerationParameters(new SecureRandom(), XXX));

        AsymmetricCipherKeyPair keys = rsaKeyPairGenerator.GenerateKeyPair();

        PrivateKeyInfo privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(keys.Private);
        // Write out an RSA private key with it's asscociated information as described in PKCS8.
        byte[] serializedPrivateBytes = privateKeyInfo.ToAsn1Object().GetDerEncoded();
        // Convert to Base64 ..
        string serializedPrivateString = Convert.ToBase64String(serializedPrivateBytes);

        SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keys.Public);
        byte[] serializedPublicBytes = publicKeyInfo.ToAsn1Object().GetDerEncoded();
        string serializedPublicString = Convert.ToBase64String(serializedPublicBytes);

If you convert the bouncycastle certificate to a .net certificate. The function to do this is in the bouncycastle lib (i believe it's in a class called DotNetUtilities). The RSACryptoServiceProvider has a function:

ToXmlString(bool includePrivateKey).

Which gives you an x representation of a certificate with if you want the private key containing all the components serialized to base64 seperately, exponent, modulus, and d (private exponent).