I have been looking all day yesterday, and I can't seem to find a working example of PGP decryption using Bouncy Castle in c#
Finally got it to work. The main issue I had with other samples was the fact that the private key ring I had included a key for signing which was coming up first when trying to load the key for decryption. This is why why I had to add a check for the ElGamalPrivateKeyParameters
type on the key.
Below is my code. Not very clean, but it works.
private static PgpPrivateKey GetPrivateKey(string privateKeyPath)
{
using (Stream keyIn = File.OpenRead(privateKeyPath))
using (Stream inputStream = PgpUtilities.GetDecoderStream(keyIn))
{
PgpSecretKeyRingBundle secretKeyRingBundle = new PgpSecretKeyRingBundle(inputStream);
PgpSecretKey key = null;
foreach (PgpSecretKeyRing kRing in secretKeyRingBundle.GetKeyRings())
{
foreach (PgpSecretKey secretKey in kRing.GetSecretKeys())
{
PgpPrivateKey privKey = secretKey.ExtractPrivateKey("1234567890".ToCharArray());
if (privKey.Key.GetType() ==
typeof (Org.BouncyCastle.Crypto.Parameters.ElGamalPrivateKeyParameters))
//Org.BouncyCastle.Crypto.Parameters.ElGamalPrivateKeyParameters
{
return privKey;
}
}
}
}
return null;
}
public static void Decrypt(Stream input, string outputpath, String privateKeyPath)
{
input = PgpUtilities.GetDecoderStream(input);
try
{
PgpObjectFactory pgpObjF = new PgpObjectFactory(input);
PgpEncryptedDataList enc;
PgpObject obj = pgpObjF.NextPgpObject();
if (obj is PgpEncryptedDataList)
{
enc = (PgpEncryptedDataList)obj;
}
else
{
enc = (PgpEncryptedDataList)pgpObjF.NextPgpObject();
}
PgpPrivateKey privKey = GetPrivateKey(privateKeyPath);
PgpPublicKeyEncryptedData pbe = enc.GetEncryptedDataObjects().Cast<PgpPublicKeyEncryptedData>().First();
Stream clear;
clear = pbe.GetDataStream(privKey);
PgpObjectFactory plainFact = new PgpObjectFactory(clear);
PgpObject message = plainFact.NextPgpObject();
if (message is PgpCompressedData)
{
PgpCompressedData cData = (PgpCompressedData)message;
Stream compDataIn = cData.GetDataStream();
PgpObjectFactory o = new PgpObjectFactory(compDataIn);
message = o.NextPgpObject();
if (message is PgpOnePassSignatureList)
{
message = o.NextPgpObject();
PgpLiteralData Ld = null;
Ld = (PgpLiteralData)message;
Stream output = File.Create(outputpath + "\\" + Ld.FileName);
Stream unc = Ld.GetInputStream();
Streams.PipeAll(unc, output);
}
else
{
PgpLiteralData Ld = null;
Ld = (PgpLiteralData)message;
//Stream output = File.Create(outputpath + "\\" + Ld.FileName);
Stream output = File.Create(outputpath);
Stream unc = Ld.GetInputStream();
Streams.PipeAll(unc, output);
}
}
}
catch (Exception e)
{
throw new Exception(e.Message);
}
}