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Decrypt and Verify

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When we receive a one pass signed and encrypted OpenPGP data we can decrypt it only if we do not wish to verify who is the sender or both decrypt and verify it in one pass. For examples demonstrating the first case when we only want to decrypt the data refer to OpenPGP decryption in .NET. The examples below show how to perform both decryption and verification with DidiSoft OpenPGP Library for .NET:

1) Decrypt and verify file with keys located in files
2) Decrypt and verify file with keys located in a KeyStore

3) Decrypt and verify string message with keys located in files
4) Decrypt and verify string message with keys located in a KeyStore

1) Decrypt and verify file with keys located in files

This example demonstrates OpenPGP decryption and verification of one pass signed and encrypted file.
Having the public key of the other party we decrypt and verify that it is the source of this signed file.

C#

using System;
using DidiSoft;
 
public class DecryptAndVerify
{
 public void Demo()
 {
    // create an instance of the library
    PGPLib pgp = new PGPLib();
 
    bool validSigning =
         pgp.DecryptAndVerifyFile(@"C:\Test\OUTPUT.pgp",
                                  @"C:\Test\private.key",
                                  "private key password",
                                  @"C:\Test\public.key",
                                  @"C:\Test\INPUT.txt");
    Console.WriteLine(validSigning);
 }
}

VB.NET

Imports System
Imports DidiSoft
 
Public Class DecryptAndVerify
 Public Sub Demo()
   ' create an instance of the library   
   Dim pgp As New PGPLib()
 
   Dim validSigning As Boolean = _
   pgp.DecryptAndVerifyFile("C:\Test\OUTPUT.pgp", _
				"C:\Test\private.key", _
				"private key password", _
				"C:\Test\public.key", _
				"C:\Test\INPUT.txt")
   Console.WriteLine(validSigning)
 End Sub
End Class

2) Decrypt and verify file with keys located in a KeyStore

In this example the public key of the sender is used for verification and our private key is used for decryption and they both are located in a KeyStore file.

C#

using System;
using DidiSoft;
 
public class KeyStoreDecryptAndVerifyFile
{
 public static void Demo()
 {
   // initialize the KeyStore
   KeyStore keyStore = new KeyStore(@"c:\key.store", "key store pass");
 
   // create an instance of the library
   PGPLib pgp = new PGPLib();
 
   // we should provide the private decryption key password too
   String decryptionKeyPassword = "private key password";
   bool validSigning = pgp.DecryptAndVerifyFile(@"c:\INPUT.pgp",
						keyStore,
						decryptionKeyPassword,
						@"c:\OUTPUT.txt");
   Console.WriteLine("Signature is valid: "+validSigning);
 }
}

VB.NET

Imports System
Imports DidiSoft
 
Public Class KeyStoreDecryptAndVerifyFile
 Public Shared Sub Demo()
    ' initialize the KeyStore
    Dim keyStore As New KeyStore("c:\key.store", "key store pass")
 
    ' create an instance of the library
    Dim pgp As New PGPLib()
 
    ' we should provide the private decryption key password too
    Dim decryptionKeyPassword As String = "private key password"
    Dim validSigning As Boolean = _
                pgp.DecryptAndVerifyFile("c:\OUTPUT.pgp", _
					  keyStore, _
					  decryptionKeyPassword, _
					  "c:\OUTPUT.txt")
    Console.WriteLine("Signature valid: " &amp; validSigning)
 End Sub
End Class

3) Decrypt and verify string message with keys located in files

If we have an encrypted string message we can decrypt it directly without writing it into a file beforehand.

C#

using System;
using System.IO;
using DidiSoft;
 
class DecryptAndVerifyString
{
 public void Demo()
 {
   // obtain encrypted and signed message
   String signedAndEncryptedMessage = ...
 
   String plainTextExtracted;
 
   // create an instance of the library
   PGPLib pgp = new PGPLib();
 
   // decrypt and verify
   bool validSigning = pgp.DecryptAndVerifyString(
                                signedAndEncryptedMessage,
				new FileInfo(@"c:\private.key"),
				"private key password",
				new FileInfo(@"c:\public.key"),
				out plainTextExtracted);
   // print the results
   if (validSigning)
   {
       Console.WriteLine("Signature is Valid");
   }
   else
   {
       Console.WriteLine("Signature is Invalid");
   }
 
   Console.WriteLine("Extracted message: " + plainTextExtracted);
 }
}

VB.NET

Imports System
Imports System.IO
Imports DidiSoft
 
Class DecryptAndVerifyString
 Public Sub Demo()
   ' obtain encrypted and signed message
   Dim signedAndEncryptedMessage As String = ...
 
   Dim plainTextExtracted As String
 
   ' create an instance of the library
   Dim pgp As New PGPLib()
 
   ' decrypt and verify
   Dim validSigning As Boolean = pgp.DecryptAndVerifyString( _
                                     signedAndEncryptedMessage, _
                                     New FileInfo("c:\private.key"), _
                                     "private key password", _
                                     New FileInfo("c:\public.key"), _
                                     plainTextExtracted)
   ' print the results
   If validSigning Then
	Console.WriteLine("Signature is Valid")
   Else
	Console.WriteLine("Signature is Invalid")
  End If
 
  Console.WriteLine("Extracted message: " + plainTextExtracted)
 End Sub
End Class

4) Decrypt and verify string message with keys located in a KeyStore

This example shows to decrypt and verify a signed and encrypted string message with keys stored in a KeyStore file.

C# 

using System;
using DidiSoft;
 
class KeyStoreDecryptAndVerifyString
{
 public static void Demo()
 {
    // obtain an OpenPGP signed and enrypted message
    String signedAndEncryptedString = ...
 
    String privateKeyDecryptionPassword = "private key password";
 
    // Extract the message and check the validity of the signature
    String plainText;
 
    // create an instance of the library
    PGPLib pgp = new PGPLib();
 
    // initialize the key store
    KeyStore ks = new KeyStore(@"c:\key.store", "key store password");
 
    bool validSignature = pgp.DecryptAndVerifyString(signedAndEncryptedString,
						     ks,
						     privateKeyDecryptionPassword,
						     out plainText);
 
    // Print the results
    Console.WriteLine("Extracted plain text message is " + plainText);
   if (validSignature)
   {
	Console.WriteLine("Signature is valid");
   }
   else
   {
	Console.WriteLine("Signature is invalid");
   }
 }
}

VB.NET

Imports System
Imports DidiSoft
 
Class KeyStoreDecryptAndVerifyString
 Public Shared Sub Demo()
   ' obtain an OpenPGP signed and enrypted message
   Dim signedAndEncryptedString As String = ...
 
   Dim privateKeyDecryptionPassword As String = "private key password"
 
   ' Extract the message and check the validity of the signature
   Dim plainText As String
 
   ' create an instance of the library
   Dim pgp As New PGPLib()
 
   ' initialize the key store
   Dim ks As New KeyStore("c:\key.store", "key store password")
 
   Dim validSignature As Boolean = _
           pgp.DecryptAndVerifyString(signedAndEncryptedString, _
                                      ks, _
                                      privateKeyDecryptionPassword, _
                                      plainText)
 
   ' Print the results
   Console.WriteLine("Extracted plain text message is " + plainText)
   If validSignature Then
	Console.WriteLine("Signature is valid")
   Else
	Console.WriteLine("Signature is invalid")
   End If
 End Sub
End Class

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