/// <summary>
/// Attempt to decrypt a PGP protected message using the matching private key.
/// </summary>
/// <param name="decryptedMessage">If successful, the decrypted message.</param>
/// <returns>Whether the decryption completed successfully.</returns>
public bool PgpDecrypt(PgpPrivateKey recipientPrivateKey, out byte[] decryptedMessage)
{
string encryptedBody = "";
// Process each MIME part.
if (MimeParts != null)
{
for (int i = 0; i < MimeParts.Count; i++)
{
MimePart mimePart = MimeParts[i];
// Check if the MIME part is encrypted or signed using PGP.
if (mimePart.Body.StartsWith("-----BEGIN PGP MESSAGE-----"))
{
encryptedBody = Functions.ReturnBetween(mimePart.Body, "-----BEGIN PGP MESSAGE-----\r\n", "\r\n-----END PGP MESSAGE-----");
break;
}
}
}
else
{
if (Body.StartsWith("-----BEGIN PGP MESSAGE-----"))
{
encryptedBody = Functions.ReturnBetween(Body, "-----BEGIN PGP MESSAGE-----\r\n", "\r\n-----END PGP MESSAGE-----");
}
}
// Process an encrypted body if found.
if (!string.IsNullOrEmpty(encryptedBody))
{
// Ignore the PGP headers.
int doubleLineBreak = encryptedBody.IndexOf("\r\n\r\n");
if (doubleLineBreak > -1)
{
encryptedBody = encryptedBody.Substring(doubleLineBreak + 4);
}
// Attempt to decrypt the message and set the body if successful.
if (Pgp.Decrypt(Encoding.UTF8.GetBytes(encryptedBody), out decryptedMessage, recipientPrivateKey))
{
// Ensure a valid encoding.
if (BodyEncoding == null)
{
BodyEncoding = Encoding.UTF8;
}
// Convert the byte array back to a string.
Body = BodyEncoding.GetString(decryptedMessage);
// If the body was successfully decrypted, attempt to decrypt attachments.
foreach (Attachment attachment in Attachments)
{
// Only process attachments with names ending in ".pgp".
if (attachment.Name.ToLower().EndsWith(".pgp"))
{
if (Pgp.Decrypt(attachment.ContentStream, out decryptedMessage, recipientPrivateKey))
{
attachment.ContentStream = new MemoryStream(decryptedMessage);
attachment.Name = attachment.Name.Substring(0, attachment.Name.Length - 4);
}
}
}
return(true);
}
else
{
return(false);
}
}
else
{
decryptedMessage = null;
return(false);
}
}
/// <summary>
/// Attempt to verify a PGP signed message using the matching public key.
/// </summary>
/// <param name="senderPublicKey">BouncyCastle public key to be used for verification.</param>
/// <returns>Whether the message's signature is verified.</returns>
public bool PgpVerifySignature(PgpPublicKey senderPublicKey)
{
string pgpSignedMessage = "";
string pgpSignature = "";
// Process each MIME part.
if (MimeParts != null)
{
int pgpSignedMessageIndex = -1;
int pgpSignatureIndex = -1;
for (int i = 0; i < MimeParts.Count; i++)
{
MimePart mimePart = MimeParts[i];
// Check if the MIME part is encrypted or signed using PGP.
if (mimePart.Body.StartsWith("-----BEGIN PGP SIGNED MESSAGE-----"))
{
pgpSignedMessageIndex = i;
}
else if (mimePart.Body.StartsWith("-----BEGIN PGP SIGNATURE-----"))
{
pgpSignatureIndex = i;
}
}
// Verify PGP signatures.
if (pgpSignedMessageIndex > -1 && pgpSignatureIndex > -1)
{
pgpSignedMessage = MimeParts[pgpSignedMessageIndex].Body;
pgpSignature = MimeParts[pgpSignatureIndex].Body;
}
}
// If the signature isn't embedded as its own MIME part, extract from the body.
if (string.IsNullOrEmpty(pgpSignedMessage) && string.IsNullOrEmpty(pgpSignature))
{
pgpSignedMessage = Functions.ReturnBetween(Body, "-----BEGIN PGP SIGNED MESSAGE-----\r\n", "\r\n-----BEGIN PGP SIGNATURE-----");
pgpSignature = Functions.ReturnBetween(Body, "-----BEGIN PGP SIGNATURE-----\r\n", "\r\n-----END PGP SIGNATURE-----");
}
// If a signature is embedded, attempt to verify.
if (!string.IsNullOrEmpty(pgpSignedMessage) && !string.IsNullOrEmpty(pgpSignature))
{
// Skip over PGP headers.
int doubleLineBreak = pgpSignedMessage.IndexOf("\r\n\r\n");
if (doubleLineBreak > -1)
{
pgpSignedMessage = pgpSignedMessage.Substring(doubleLineBreak + 4);
}
doubleLineBreak = pgpSignature.IndexOf("\r\n\r\n");
if (doubleLineBreak > -1)
{
pgpSignature = pgpSignature.Substring(doubleLineBreak + 4);
}
// Verify the message with its signature.
if (!string.IsNullOrEmpty(pgpSignedMessage) && !string.IsNullOrEmpty(pgpSignature))
{
bool pgpSignatureVerified = Pgp.VerifySignature(Encoding.UTF8.GetBytes(pgpSignedMessage),
Encoding.UTF8.GetBytes(Functions.FromBase64(pgpSignature)), senderPublicKey);
if (pgpSignatureVerified)
{
Body = pgpSignedMessage;
}
return(pgpSignatureVerified);
}
}
return(false);
}
