BouncyCastle in-memory PGP encryption in C#
I've been trying to use the BouncyCastle library to do PGP encryption/decryption. I have some code that I need to modify to use streams only - no files.
I tried removing the PgpUtilities.WriteFileToLiteralData() and then making it return a stream, but it didn't work (output stream was empty).
To be more clear here is what the method should be:
public static Stream EncryptFile(MemoryStream inputStream, PgpPublicKey encKey, bool withIntegrityCheck)
Here is the code I need to modify:
private static void EncryptFile(Stream outputStream, string fileName, PgpPublicKey encKey, bool armor, bool withIntegrityCheck)
{
if (armor)
outputStream = new ArmoredOutputStream(outputStream);
try
{
MemoryStream bOut = new MemoryStream();
PgpCompressedDataGenerator comData = new PgpCompressedDataGenerator(
CompressionAlgorithmTag.Zip);
PgpUtilities.WriteFileToLiteralData(
comData.Open(bOut),
PgpLiteralData.Binary,
new FileInfo(fileName));
comData.Close();
PgpEncryptedDataGenerator cPk = new PgpEncryptedDataGenerator(
SymmetricKeyAlgorithmTag.Cast5, withIntegrityCheck, new SecureRandom());
cPk.AddMethod(encKey);
byte[] bytes = bOut.ToArray();
Stream cOut = cPk.Open(outputStream, bytes.Length);
cOut.Write(bytes, 0, bytes.Length);
cOut.Close();
if (armor)
outputStream.Close();
}
catch (PgpException e)
{
Console.Error.WriteLine(e);
Exception underlyingException = e.InnerException;
if (underlyingException != null)
{
Console.Error.WriteLine(underlyingException.Message);
Console.Error.WriteLine(underlyingException.StackTrace);
}
}
}
public void EncryptFile(string filePath, string publicKeyFile, string pathToSaveFile)
{
Stream keyIn, fos;
keyIn = File.OpenRead(publicKeyFile);
string[] fileSplit = filePath.Split('\\');
string fileName = fileSplit[fileSplit.Length - 1];
fos = File.Create(pathToSaveFile + fileName + ".asc");
EncryptFile(fos, filePath, ReadPublicKey(keyIn), true, true);
keyIn.Close();
fos.Close();
}
Answer
I got it working. The code uses byte[] for input and output of both decryption and encryption - no files.
Here is the full class:
class PGP
{
public PGP() { }
/**
* A simple routine that opens a key ring file and loads the first available key suitable for
* encryption.
*
* @param in
* @return
* @m_out
* @
*/
public static PgpPublicKey ReadPublicKey(Stream inputStream)
{
inputStream = PgpUtilities.GetDecoderStream(inputStream);
PgpPublicKeyRingBundle pgpPub = new PgpPublicKeyRingBundle(inputStream);
//
// we just loop through the collection till we find a key suitable for encryption, in the real
// world you would probably want to be a bit smarter about this.
//
//
// iterate through the key rings.
//
foreach (PgpPublicKeyRing kRing in pgpPub.GetKeyRings())
{
foreach (PgpPublicKey k in kRing.GetPublicKeys())
{
if (k.IsEncryptionKey)
return k;
}
}
throw new ArgumentException("Can't find encryption key in key ring.");
}
/**
* Search a secret key ring collection for a secret key corresponding to
* keyId if it exists.
*
* @param pgpSec a secret key ring collection.
* @param keyId keyId we want.
* @param pass passphrase to decrypt secret key with.
* @return
*/
private static PgpPrivateKey FindSecretKey(PgpSecretKeyRingBundle pgpSec, long keyId, char[] pass)
{
PgpSecretKey pgpSecKey = pgpSec.GetSecretKey(keyId);
if (pgpSecKey == null)
return null;
return pgpSecKey.ExtractPrivateKey(pass);
}
/**
* Decrypt the byte array passed into inputData and return it as
* another byte array.
*
* @param inputData - the data to decrypt
* @param keyIn - a stream from your private keyring file
* @param passCode - the password
* @return - decrypted data as byte array
*/
public static byte[] Decrypt(byte[] inputData, Stream keyIn, string passCode)
{
byte[] error = Encoding.ASCII.GetBytes("ERROR");
Stream inputStream = new MemoryStream(inputData);
inputStream = PgpUtilities.GetDecoderStream(inputStream);
MemoryStream decoded = new MemoryStream();
try
{
PgpObjectFactory pgpF = new PgpObjectFactory(inputStream);
PgpEncryptedDataList enc;
PgpObject o = pgpF.NextPgpObject();
//
// the first object might be a PGP marker packet.
//
if (o is PgpEncryptedDataList)
enc = (PgpEncryptedDataList)o;
else
enc = (PgpEncryptedDataList)pgpF.NextPgpObject();
//
// find the secret key
//
PgpPrivateKey sKey = null;
PgpPublicKeyEncryptedData pbe = null;
PgpSecretKeyRingBundle pgpSec = new PgpSecretKeyRingBundle(
PgpUtilities.GetDecoderStream(keyIn));
foreach (PgpPublicKeyEncryptedData pked in enc.GetEncryptedDataObjects())
{
sKey = FindSecretKey(pgpSec, pked.KeyId, passCode.ToCharArray());
if (sKey != null)
{
pbe = pked;
break;
}
}
if (sKey == null)
throw new ArgumentException("secret key for message not found.");
Stream clear = pbe.GetDataStream(sKey);
PgpObjectFactory plainFact = new PgpObjectFactory(clear);
PgpObject message = plainFact.NextPgpObject();
if (message is PgpCompressedData)
{
PgpCompressedData cData = (PgpCompressedData)message;
PgpObjectFactory pgpFact = new PgpObjectFactory(cData.GetDataStream());
message = pgpFact.NextPgpObject();
}
if (message is PgpLiteralData)
{
PgpLiteralData ld = (PgpLiteralData)message;
Stream unc = ld.GetInputStream();
Streams.PipeAll(unc, decoded);
}
else if (message is PgpOnePassSignatureList)
throw new PgpException("encrypted message contains a signed message - not literal data.");
else
throw new PgpException("message is not a simple encrypted file - type unknown.");
if (pbe.IsIntegrityProtected())
{
if (!pbe.Verify())
MessageBox.Show(null, "Message failed integrity check.", "PGP Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
else
MessageBox.Show(null, "Message integrity check passed.", "PGP Error", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
else
{
MessageBox.Show(null, "No message integrity check.", "PGP Error", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
return decoded.ToArray();
}
catch (Exception e)
{
if (e.Message.StartsWith("Checksum mismatch"))
MessageBox.Show(null, "Likely invalid passcode. Possible data corruption.", "Invalid Passcode", MessageBoxButtons.OK, MessageBoxIcon.Error);
else if (e.Message.StartsWith("Object reference not"))
MessageBox.Show(null, "PGP data does not exist.", "PGP Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
else if (e.Message.StartsWith("Premature end of stream"))
MessageBox.Show(null, "Partial PGP data found.", "PGP Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
else
MessageBox.Show(null, e.Message, "PGP Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
Exception underlyingException = e.InnerException;
if (underlyingException != null)
MessageBox.Show(null, underlyingException.Message, "PGP Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
return error;
}
}
/**
* Encrypt the data.
*
* @param inputData - byte array to encrypt
* @param passPhrase - the password returned by "ReadPublicKey"
* @param withIntegrityCheck - check the data for errors
* @param armor - protect the data streams
* @return - encrypted byte array
*/
public static byte[] Encrypt(byte[] inputData, PgpPublicKey passPhrase, bool withIntegrityCheck, bool armor)
{
byte[] processedData = Compress(inputData, PgpLiteralData.Console, CompressionAlgorithmTag.Uncompressed);
MemoryStream bOut = new MemoryStream();
Stream output = bOut;
if (armor)
output = new ArmoredOutputStream(output);
PgpEncryptedDataGenerator encGen = new PgpEncryptedDataGenerator(SymmetricKeyAlgorithmTag.Cast5, withIntegrityCheck, new SecureRandom());
encGen.AddMethod(passPhrase);
Stream encOut = encGen.Open(output, processedData.Length);
encOut.Write(processedData, 0, processedData.Length);
encOut.Close();
if (armor)
output.Close();
return bOut.ToArray();
}
private static byte[] Compress(byte[] clearData, string fileName, CompressionAlgorithmTag algorithm)
{
MemoryStream bOut = new MemoryStream();
PgpCompressedDataGenerator comData = new PgpCompressedDataGenerator(algorithm);
Stream cos = comData.Open(bOut); // open it with the final destination
PgpLiteralDataGenerator lData = new PgpLiteralDataGenerator();
// we want to Generate compressed data. This might be a user option later,
// in which case we would pass in bOut.
Stream pOut = lData.Open(
cos, // the compressed output stream
PgpLiteralData.Binary,
fileName, // "filename" to store
clearData.Length, // length of clear data
DateTime.UtcNow // current time
);
pOut.Write(clearData, 0, clearData.Length);
pOut.Close();
comData.Close();
return bOut.ToArray();
}
}