how to get private key from PEM file?

Question

i have a .PEM file that includes public key and a private key for SSL data transfer like this:

-----BEGIN RSA PRIVATE KEY-----
      private key data
-----EN         


        

Answer 1

There's an article on the Code Project that has all the code you need to do this. It's just a couple of classes so it's a light-weight solution.

To get the bytes for either a certificate or a key from the PEM file the following method will work, regardless of the order of the key and certificate in the file.

 byte[] GetBytesFromPEM( string pemString, string section )
 {
     var header = String.Format("-----BEGIN {0}-----", section);
     var footer = String.Format("-----END {0}-----", section);

     var start= pemString.IndexOf(header, StringComparison.Ordinal);
     if( start < 0 )
        return null;

     start += header.Length;
     var end = pemString.IndexOf(footer, start, StringComparison.Ordinal) - start;

     if( end < 0 )
        return null;

     return Convert.FromBase64String( pemString.Substring( start, end ) );
 }

Load the PEM file into a string and call the method above to get the bytes that represent the certificate. Next you pass the obtained bytes to the constructor of an X509Certificate2 :

 var pem = System.IO.File.ReadAllText( "c:\\myKey.pem" );
 byte[] certBuffer = GetBytesFromPEM( pem, "CERTIFICATE" );
 var certificate = new X509Certificate2( certBuffer );

Loading the (RSA) private key from the PEM file is a bit more complicated but you'll find support for that in the above mentioned article as well using the Crypto.DecodeRsaPrivateKey method.