Cannot Load private key from a RSA PRIVATE KEY file in C#

Question

I want to sign some data with RSA.SignHash(). I've created a RSA private key file via the following command in Linux OpenSSL.

openssl genrsa -out private_key.pem 1024

But when I want to load this key by an object of X509Certificate2, get the "Cannot find the requested object." exception. Here is my code:

string keyFilePath = @"C:\Keys\private_key.pem";
X509Certificate2 cert = new X509Certificate2(keyFilePath);

I've used the Chilkat library and everything works fine, But doesn't Microsoft have any walk-though to approach it without any third-party tools? Here is my pem file content:

Its the pem format that is the issue, see: [how to get private key from PEM file?](https://stackoverflow.com/questions/7400500/how-to-get-private-key-from-pem-file) — Alex K., May 30 '17 at 13:05
Dear @AlexK. and Simone Cifani, I've tried the other article (https://stackoverflow.com/questions/7400500/how-to-get-private-key-from-pem-file). And same exception. I do not have any Certificate. I have a private key. — Soheil Farahani, May 30 '17 at 13:10
Just stating the obvious: a key is not a certificate. It does not make sense to try to load a private key into a certificate object. — jww, May 30 '17 at 13:44
Dear @jww please direct me how to sign with just a private key. — Soheil Farahani, May 30 '17 at 13:46
[Signing and verifying signatures with RSA C#](https://stackoverflow.com/q/8437288/608639), [how to sign bytes using my own rsa private key using rs256 algorithm?](https://stackoverflow.com/q/25909044/608639), [Signing data with private key in c#](https://stackoverflow.com/q/31828420/608639), [How can I sign a file using RSA and SHA256 with .NET?](https://stackoverflow.com/q/7444586/608639), [Signing a string with RSA private key on .NET?](https://stackoverflow.com/q/3169829/608639), etc. — jww, May 30 '17 at 13:53

score 1 · Answer 1 · answered May 30 '17 at 13:42

No, there is no friendly way to do it without third-party tools. If you only have private key then IMHO new X509Certificate2(keyFilePath) does not make sense.

What you could do is implement (or use a library) to parse the private key. Then encode parsed private key parameters to a xml structure that can be imported using RSA.FromXmlString.

Cannot Load private key from a RSA PRIVATE KEY file in C#

1 Answers1