/// <summary>
/// Attempt to sign a PGP message using the specific private key.
/// </summary>
/// <param name="messageStream">Stream containing the message to sign.</param>
/// <param name="signatureStream">Stream to write the signature into.</param>
/// <param name="senderPublicKey">The BouncyCastle public key associated with the signature.</param>
/// <param name="senderPrivateKey">The BouncyCastle private key to be used for signing.</param>
/// <param name="hashAlgorithmTag">The hash algorithm tag to use for signing.</param>
/// <param name="armor">Whether to wrap the message with ASCII armor.</param>
/// <returns>Whether the signature completed successfully.</returns>
public static bool Sign(Stream messageStream, Stream signatureStream, PgpPublicKey senderPublicKey, PgpPrivateKey senderPrivateKey, HashAlgorithmTag hashAlgorithmTag = HashAlgorithmTag.Sha256, bool armor = true)
{
// Create a signature generator.
PgpSignatureGenerator signatureGenerator = new PgpSignatureGenerator(senderPublicKey.Algorithm, hashAlgorithmTag);
signatureGenerator.InitSign(PgpSignature.BinaryDocument, senderPrivateKey);
// Add the public key user ID.
foreach (string userId in senderPublicKey.GetUserIds())
{
PgpSignatureSubpacketGenerator signatureSubGenerator = new PgpSignatureSubpacketGenerator();
signatureSubGenerator.SetSignerUserId(false, userId);
signatureGenerator.SetHashedSubpackets(signatureSubGenerator.Generate());
break;
}
// Handle ASCII armor.
if (armor)
{
using (ArmoredOutputStream armoredStream = new ArmoredOutputStream(signatureStream))
{
armoredStream.BeginClearText(hashAlgorithmTag);
// Process each character in the message.
int messageChar;
while ((messageChar = messageStream.ReadByte()) >= 0)
{
armoredStream.WriteByte((byte)messageChar);
signatureGenerator.Update((byte)messageChar);
}
armoredStream.EndClearText();
using (BcpgOutputStream bcpgStream = new BcpgOutputStream(armoredStream))
{
signatureGenerator.Generate().Encode(bcpgStream);
}
}
}
else
{
// Process each character in the message.
int messageChar;
while ((messageChar = messageStream.ReadByte()) >= 0)
{
signatureGenerator.Update((byte)messageChar);
}
signatureGenerator.Generate().Encode(signatureStream);
}
return(true);
}
