Decode a PKCS#12 file

Question

I am looking for ways to decode a PKCS#12 file in .NET, I need to extract the private key and any certificates so that i can programatically access the following.

• modulus
• publicExponent
• privateExponent
• prime1
• prime2
• exponent1
• exponent2
• coefficient

I need this informatio so that i can successfully use PKCS#11 to create a private key and cetificate on a USB token.

I have found a website that uses OpenSSL to output this data. I was pretty excited when I found OpenSSL.NET however the functionallity to split PKCS#12 files hasn't been implemented yet. I was wondering if anyone knew of any altenatives.

Thanks

Rohan

Answer 1

I've used bouncy castle API extensibly on a recent project, on its Java port, and it works wonders, flawlessly.

I bet their C# isn't much different, and it does a really good work at what is targeted.

http://www.bouncycastle.org/

Answer 2

Cheers Manuel,

I downloaded the Bouncy Castle API and it didn't take long to find what i needed. The source code includes an extensive list of unit tests.

static void Main(string[] args)
{
    char[] password = new char[] {'p','a','s','s','w','o','r','d'};

    using(StreamReader reader = new StreamReader(@"Test.pfx"))
    {
        Pkcs12Store store = new Pkcs12Store(reader.BaseStream,password);
        foreach (string n in store.Aliases)
        {
            if(store.IsKeyEntry(n))
            {
                AsymmetricKeyEntry key = store.GetKey(n);

                if(key.Key.IsPrivate)
                {
                    RsaPrivateCrtKeyParameters parameters = key.Key as RsaPrivateCrtKeyParameters;
                    Console.WriteLine(parameters.PublicExponent);
                }                       
            }
        }
    }
}

Answer 3

AFAIK you have to pinvoke out to the win32 crypto libraries, see this MSDN article: http://msdn.microsoft.com/en-us/library/ms867088.aspx

Answer 4

You should be able to use OpenSSL directly via pInvoke. Maybe you could contribute back to the OpenSSL.NET project when you get it working.

The win32 crypto providers is a good alternative, but it can be a bit inflexible in terms of what formats it can parse and generate.