C#

Duplicate openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

See more RSA Examples

Demonstrates how to duplicate the creation of an RSA signature produced by this OpenSSL command:

openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

C#

bool success = false;

// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.PrivateKey pkey = new Chilkat.PrivateKey();

// Load the private key from an RSA PEM file:
success = pkey.LoadPemFile("myKey.pem");

Chilkat.Rsa rsa = new Chilkat.Rsa();

// Import the private key into the RSA component:
success = rsa.UsePrivateKey(pkey);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// OpenSSL uses BigEndian byte ordering:
rsa.LittleEndian = false;

// The resulting signature will be a Base64 string:
rsa.EncodingMode = "base64";

// For simplicity, we're not loading
// the data to be signed from a file.  We are instead simply
// using a literal string value.  
string strData = "This is the text to be signed.";

// Hash the input using MD5, and then sign the hash:
// Other valid hash algorithm choices are "md2" and "sha-1".
string base64Sig = rsa.SignStringENC(strData,"md5");

Debug.WriteLine(base64Sig);

Debug.WriteLine("Success!");