I've researched a bit about how to achieve what I said in the question and found several APIs but most of them look very complicated and since I'm just a noobie in this area I just want a simple method like:
public String Encrypt(String message, PublicKey publicKey)
Don't know if this can be done? If not then please someone enlighten me another way to achieve this :)
Thank you.
UPDATE:
So far I have only seen that all of the library for OpenPGP encryption require both the public key and private key to do the encrypt while I only want to encrypt with the public key (because I don't have the private key to use it)!
I found a tutorial here but it requires both Secret Key and Public Key to encrypt data. However I've modified the codes a bit to only require public key (no signing, no compress) and thought I should publish it here in case anyone also looking for a solution for this question. Belows is the modified codes, all the credits for the author - Mr. Kim.
public class PgpEncrypt
{
private PgpEncryptionKeys m_encryptionKeys;
private const int BufferSize = 0x10000;
/// <summary>
/// Instantiate a new PgpEncrypt class with initialized PgpEncryptionKeys.
/// </summary>
/// <param name="encryptionKeys"></param>
/// <exception cref="ArgumentNullException">encryptionKeys is null</exception>
public PgpEncrypt(PgpEncryptionKeys encryptionKeys)
{
if (encryptionKeys == null)
{
throw new ArgumentNullException("encryptionKeys", "encryptionKeys is null.");
}
m_encryptionKeys = encryptionKeys;
}
/// <summary>
/// Encrypt and sign the file pointed to by unencryptedFileInfo and
/// write the encrypted content to outputStream.
/// </summary>
/// <param name="outputStream">The stream that will contain the
/// encrypted data when this method returns.</param>
/// <param name="fileName">FileInfo of the file to encrypt</param>
public void Encrypt(Stream outputStream, FileInfo unencryptedFileInfo)
{
if (outputStream == null)
{
throw new ArgumentNullException("outputStream", "outputStream is null.");
}
if (unencryptedFileInfo == null)
{
throw new ArgumentNullException("unencryptedFileInfo", "unencryptedFileInfo is null.");
}
if (!File.Exists(unencryptedFileInfo.FullName))
{
throw new ArgumentException("File to encrypt not found.");
}
using (Stream encryptedOut = ChainEncryptedOut(outputStream))
{
using (Stream literalOut = ChainLiteralOut(encryptedOut, unencryptedFileInfo))
using (FileStream inputFile = unencryptedFileInfo.OpenRead())
{
WriteOutput(literalOut, inputFile);
}
}
}
private static void WriteOutput(Stream literalOut,
FileStream inputFile)
{
int length = 0;
byte[] buf = new byte[BufferSize];
while ((length = inputFile.Read(buf, 0, buf.Length)) > 0)
{
literalOut.Write(buf, 0, length);
}
}
private Stream ChainEncryptedOut(Stream outputStream)
{
PgpEncryptedDataGenerator encryptedDataGenerator;
encryptedDataGenerator =
new PgpEncryptedDataGenerator(SymmetricKeyAlgorithmTag.TripleDes,
new SecureRandom());
encryptedDataGenerator.AddMethod(m_encryptionKeys.PublicKey);
return encryptedDataGenerator.Open(outputStream, new byte[BufferSize]);
}
private static Stream ChainLiteralOut(Stream encryptedOut, FileInfo file)
{
PgpLiteralDataGenerator pgpLiteralDataGenerator = new PgpLiteralDataGenerator();
return pgpLiteralDataGenerator.Open(encryptedOut, PgpLiteralData.Binary,
file);
}
}
Of course to run these codes you have to include BouncyCastle library in your project.
I've tested encrypting and then decrypting and it runs fine :)