OpenPGP Knowledge Base (Java, C#, VB.NET examples and solutions)

Should DidiSoft OpenPGP Library for .NET provide strong name assemblies or unsigned assemblies?

Last week we have sent a short survey to subscribers for our OpenPGP Library for .NET mailing list. The survey had only one question:

Should DidiSoft OpenPGP Library for .NET provide strong name (signed) assemblies (DLL’s) or plain unsigned assemblies?

At the end of this post you will find the results of the survey, but first lets explain why did we made it.

DidiSoft OpenPGP Library for .NET was providing limited PGP emails support due to limitations in the System.Net.Mail namespace implementation regarding the MIME email formats (in fact we supported only PGP-inline emails). Recently we had received a numerous requests for additional support for PGP/MIME email format. In order to implement it we decided to use the open source MimeKit library but this is the moment where we were hit with this case:

+-------+        +---+         +--------+
|   B   +------->+ A +<--------+    D   |
+---+---+        +---+         +--------+
^                               ^
|                               |
|                               |
+---+---+                       +---+---+
|  C.1  |                       |  C.2  |
+-------+                       +-------+

Assembly A needs to use assemblies B and D, which reference different versions of assembly C. Of course this can be resolved with binding redirect in the app.config or dynamically in the AppDomain.CurrentDomain.AssemblyResolve event. But our aim was to provide a DidiSoft.Pgp.Mail.dll which use will be as simple as just referencing it straight away.

Digging for more information in Stackoverflow and MSDN we found out that probably the days when strong named assemblies were a must may have passed away. In order to hear what our community thinks we decided to file the survey. And here are the results:

The results are self explanatory – we must provide both strong named DLLs and unsigned too.

 

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Weird symbols in emails to BlackBerry clients

Sending PGP/MIME emails to BlackBerry clients may lead to weird symbols in front of given special characters. This is a hard to be solved bug as it has nothing to do with OpenPGP. The OpenPGP messages created with DidiSoft OpenPGP Library for Java and OpenPGP Library for Android are correct and identical when decrypted up to byte array level with those created with other OpenPGP compatible apps including the BlackBerry PGP support.

One of our clients experienced in his Android app this strange behavior when sending encrypted emails to BlackBerry. Digging deeply in this use case we finally resolved the case to be related to a weird expectation in the PGP/MIME format itself, coded in the BlackBerry PGP support.

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Exchanging encrypted data with Bank of America

Bank of America accepts OpenPGP encrypted files from its clients. Unfortunately in the official technical documentation that they provide it is not very clear how to create the proper format which they will accept. In order to easy you we will show bellow a small code snippet that will illustrate how to create such encrypted file with the help of DidiSoft OpenPGP Library for Java. Similar result can be achieved for other programming environments with the corresponding products offered by DidiSoft.

The example code snippet below will create signed and encrypted data in the format requested by Bank of America:

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  PGPLib pgp = new PGPLib();
  boolean asciiOutput = true;
  pgp.signAndEncryptFileVersion3("c:\\data.txt", "c:\\my_private_key.asc", "my key password", "c:\\BoA_key.asc", "c:\\encrypted.pgp", asciiOutput);

The key file BoA_key.asc is assumed to be the text file containing Bank of America’s public PGP key. The file my_private_key.asc file shall be your private key corresponding to the public key you have uploaded already to Bank of America. The other parameters shall be self explanatory.

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OraRSA 1.1 offering various SHA based signings

DidiSoft OraRSA version 1.1 was released today. It offers to customize the digital signature algorithm in contrast to version 1.0 where only SHA1withRSA was available.

How to use the new algorithms?

In order to use the new algorithms, you must specify the algorithm needed as the last parameter of the ORA_RSA.SIGN and ORA_RSA.VERIFY methods. Available values are:

ORA_RSA.HASH_SHA1 for SHA1withRSA
ORA_RSA.HASH_SHA224 for SHA224withRSA
ORA_RSA.HASH_SHA256 for SHA256withRSA
ORA_RSA.HASH_SHA384 for SHA384withRSA
ORA_RSA.HASH_SHA512 for SHA512withRSA

Upgrade from version 1.0

In order to upgrade from version 1.0 you must first unload the version 1.0 JAR files:

dropjava.sh/.bat -r -v – u user/pass [extraction folder]\SetupFiles\jce-jdk13-152.jar
dropjava.sh/.bat -r -v – u user/pass [extraction folder]\SetupFiles\ora-rsa-1.0.0.jar

Then continue like a normal Setup.
 

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IdNotFoundException

Executing procedures from the dbms_java Oracle PL/SQL package may result in a strange IdNotFoundException like:

ORA-29532: Java call terminated by uncaught Java exception: oracle.aurora.vm.IdNotFoundException: user : user or role id does not exist

This is very common when granting java.io.FilePermission:

call dbms_java.grant_permission('user', 'java.io.FilePermission', 'C:/MyFolder/ora-pgp-1.1.0.jar', 'read');

If you experience such error try changing the user(schema) name to Uppercase.

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OpenPGP Library for .NET 1.7.14 with Web of Trust

DidiSoft OpenPGP Library for .NET 1.7.14 was released today offering extended support for OpenPGP Web of Trust.

In previous versions of the library only setting own trust was available and plain signing of keys.

With this new release keys status can be checked by Trust amount and Verified status. We can also sign public keys with plain and trust signatures, with the option for specifying trust depth.

Check the online Tutorial for Web of Trust in order to learn this new functionality.

Upgrade notes

With this version of the library newly generated keys have Trust value of Ultimate automatically. Unfortunately if we have key pairs generated with previous versions of the library, they have Trust value Unknown. We can upgrade them with a one time execution of the code below:

C#

// ks1 is of type DidiSoft.Pgp.KeyStore
foreach (KeyPairInformation k in ks1.GetKeys())
{
      if (key.HasPrivateKey)
      {
            ks1.SetTrust(k.KeyIdHex, TrustLevel.Ultimate);
      }
}

VB.NET

' ks1 is of type DidiSoft.Pgp.KeyStore
For Each k As KeyPairInformation In ks1.GetKeys()
  If key.HasPrivateKey Then
    ks1.SetTrust(k.KeyIdHex, TrustLevel.Ultimate)
  End If
Next

 

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OpenPGP Library for .NET in Mono

DidiSoft OpenPGP Library for .NET can be used without any problems in Mono projects under Mac OSX and Linux.

The library DLL files that you have to reference in your Mono project are the ones located in the root of the \Bin folder.

A limitation for Mono developers is that they have to first install the library setup on a Windows machine in order to get the DLL files and then copy them on their Mac OSX or Linux development station.

 

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Using a public key by mistake when decrypting

A common scenario that we have evidenced in our technical support practice for DidiSoft OpenPGP Library for .NET is that some customers by mistake try to decrypt .pgp files with an OpenPGP public key.

Although the exception was of class DidiSoft.Pgp.Exceptions.WrongPrivateKeyException,  the exception text so far wasn’t very helpful and it stated: “Decryption of data encrypted using KEY-ID(s) : XXX failed, The provided key is not a valid OpenPGP private key.”.

As of version 1.7.11.11 the library was updated to check if the supplied key is a public key and in that case the exception will be “Decryption of data encrypted using KEY-ID(s) : XXX failed, The provided key is a Public Key (You need a Private Key for decryption!)

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Invoking OpenPGP Library for .NET from MS SQL Server

In this article we are going to illustrate how to invoke DidiSoft OpenPGP Library for .NET from MS SQL Server (tm) stored procedures and T-SQL code.

We also provide a dedicated set of Transact-SQL routines in the product MsSqlPGP.

Note: This information applies to MS SQL Server 2005 and above. All the demonstrated code below should be executed from SQL Server Management Studio ™ or similar environment, if not specified otherwise.

Table of Contents

Database configuration

In order to allow execution of .NET CLR code in a database, a special setting has to be activated for it:

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sp_configure 'clr enabled', 1;
GO
RECONFIGURE;

The database must allow unsafe code:

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ALTER DATABASE MyDatabase SET TRUSTWORTHY ON;

Assembly registration

The next step is to register the DLL files of the library:

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CREATE ASSEMBLY [BouncyCastle.CryptoExt]
FROM 'C:\Program Files (x86)\OpenPGP Library for .NET 1.7.10\Bin\BouncyCastle.CryptoExt.dll'
WITH PERMISSION_SET = UNSAFE;
 
CREATE ASSEMBLY [DidiSoft.Pgp]
FROM 'C:\Program Files (x86)\OpenPGP Library for .NET 1.7.10\Bin\DidiSoft.Pgp.dll'
WITH PERMISSION_SET = UNSAFE;

Wrapping the OpenPGP functionality in Stored procedures

In order to use the functionality provided by the library, we have to create wrappers as managed Stored procedures. Below is an example that exposes the basic encryption and decryption methods offered by the library:

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using System;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
 
using DidiSoft.Pgp;
 
namespace MyStoredProcedures
{
    public partial class MsSqlPgp
    {
        [SqlProcedure()]
        public static void EncryptFile(SqlString data, SqlString publicKey, SqlString outFile)
        {
            PGPLib pgp = new PGPLib();
            pgp.EncryptFile(data.Value, publicKey.Value, outFile.Value);
        }
 
        [SqlProcedure()]
        public static void DecryptFile(SqlString data, 
                                       SqlString privateKey, 
                                       SqlString keyPassword, 
                                       SqlString outFile)
        {
            PGPLib pgp = new PGPLib();
            pgp.DecryptFile(data.Value, privateKey.Value, keyPassword.Value, outFile.Value);
        }
    }
}

Of course, the assembly where the above code resides must also be registered in the same database. Let’s assume that it is registered with the alias MyStoredProcedures. Each of its methods must be registered as a stored procedure:

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CREATE PROCEDURE usp_PgpEncryptFile
@dataFile nvarchar(MAX),
@publicKey nvarchar(MAX),
@OUTFILE nvarchar(MAX)
AS EXTERNAL NAME [MyStoredProcedures].[MyStoredProcedures].EncryptFile;
 
CREATE PROCEDURE usp_PgpDecryptFile
@pgpFile nvarchar(MAX),
@privateKey nvarchar(MAX),
@keyPassword nvarchar(MAX),
@OUTFILE nvarchar(MAX)
AS EXTERNAL NAME [MyStoredProcedures].[MyStoredProcedures.MsSqlPgp].DecryptFile;

Invoking the wrapped Stored procedures

The invocation of the wrapped code is no different than any other stored procedure call:

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EXEC usp_PgpEncryptFile 'c:\Test\mydata.txt', 'c:\Test\public.asc', 'c:\Test\output.pgp';
 
EXEC usp_PgpDecryptFile 'c:\Test\input.pgp', 'c:\Test\private.asc', 'my password', 'c:\Test\output.txt';

Upgrading the library

In order to upgrade the library to a newer version we have to first DROP any linked stored procedure, and afterwards DROP the assemblies, but in reverse order:

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DROP ASSEMBLY [DidiSoft.Pgp];
DROP ASSEMBLY [BouncyCastle.CryptoExt];

After that we shall proceed as the normal setup.

Summary

This chapter illustrated how to invoke functionality from DidiSoft OpenPGP Library for .NET in MS SQL Server ™ hosted environment.

If you need a complete solution with Transact-SQL OpenPGP cryptography, check our dedicated product MsSqlPGP.

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premature end of stream in PartialInputStream

The latest release of DidiSoft OpenPGP Library for .NET (1.7.9.14) and OpenPGP Library for Java (2.6.6.3) ship with bug fix for the error “premature end of stream in PartialInputStream“.

The error “premature end of stream in PartialInputStream” may be observed when trying to decrypt .pgp data with wrong internal length indicators , usually when the encrypted content is text data. Example of such data can be found at http://bouncy-castle.1462172.n4.nabble.com/potential-bug-premature-end-of-stream-exception-in-pgp-message-td4302017.html

In order to avoid this error, please make sure that you are using the latest version of the libraries.

The DidiSoft Team.

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