Associate a private key with the X509Certificate2 class in .net

For everyone else with the same problem, I found a neat little piece of code that let's you do exactly that:

http://www.codeproject.com/Articles/162194/Certificates-to-DB-and-Back

byte[] certBuffer = Helpers.GetBytesFromPEM(publicCert, PemStringType.Certificate);
byte[] keyBuffer  = Helpers.GetBytesFromPEM(privateKey, PemStringType.RsaPrivateKey);

X509Certificate2 certificate = new X509Certificate2(certBuffer, password);

RSACryptoServiceProvider prov = Crypto.DecodeRsaPrivateKey(keyBuffer);
certificate.PrivateKey = prov;

EDIT: The code for the Helper method (which otherwise requires a codeproject login) is as follows:

public static byte[] GetBytesFromPEM(string pemString, PemStringType type)
{
    string header; string footer;
    switch (type)
    {
        case PemStringType.Certificate:
            header = "-----BEGIN CERTIFICATE-----";
            footer = "-----END CERTIFICATE-----";
            break;
        case PemStringType.RsaPrivateKey:
            header = "-----BEGIN RSA PRIVATE KEY-----";
            footer = "-----END RSA PRIVATE KEY-----";
            break;
        default:
            return null;
    }

    int start = pemString.IndexOf(header) + header.Length;
    int end = pemString.IndexOf(footer, start) - start;
    return Convert.FromBase64String(pemString.Substring(start, end));
}

Update

As of .NET 5 you can simply use CreateFromPem(ReadOnlySpan, ReadOnlySpan):

Creates a new X509 certificate from the contents of an RFC 7468 PEM-encoded certificate and private key.

example:

X509Certificate2 cert = X509Certificate2.CreateFromPem(
                certPem, //The text of the PEM-encoded X509 certificate.
                keyPem //The text of the PEM-encoded private key.
            );

Or if you have a string with both the cert and its private key, you can pass it in for both the cert arg and the key arg:

X509Certificate2 cert = X509Certificate2.CreateFromPem(
                certPem, //The text of the PEM-encoded X509 certificate.
                certPem// The text of the PEM-encoded private key.
            );

You can save yourself the hassle of copy-pasting all that code and store the private key next to the certificate in a pfx/pkcs#12 file:

openssl pkcs12 -export -in my.cer -inkey my.key -out mycert.pfx

You'll have to supply a password, which you have to pass to the constructor of X509Certificate2:

X509Certificate2 cert = new X509Certificate2("mycert.pfx","password");